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CrosslinkWinter 2002/2003 Vol. 4 No. 1

Cover: Karl Jacobs

Contents

4 The Path to Mission SuccessRay JohnsonThe formal launch verification that Aerospace performs for the Air Forcerepresents a fundamental part of the flight readiness certification for each mission.

5 Ballistic Missiles and Reentry Systems: The Critical YearsRichard A. HartunianFor nearly 20 years, Aerospace played a vital role in advancing the nation’s strategic ballistic missile and reentry system capabilities.

10 A Stellar RendezvousSteven R. StromThe Gemini program brought two orbiting American spacecraft together for the first time—and Aerospace helped arrange the meeting.

16 A Complete Range of Launch ActivitiesJoseph F. Wambolt and Jimmy F. KephartThe Eastern and Western launch ranges have a long and illustrioushistory—with a few chapters written by Aerospace.

22 The Air Force Space Shuttle Program: A Brief HistoryE. J. TomeiThe Air Force had high hopes for its West Coast shuttle complex. But despite years of preparation, this state-of-the-art facility never saw a shuttle launch.

26 Medium Launch Vehicles for Satellite DeliveryJoseph F. WamboltDecommissioned as weapons systems, early ballistic missiles made a successful transition to the U.S. space program, providing vital medium-lift capacity for military and scientific missions.

32 Epic Proportions: The Titan Launch VehicleArt FalconerFor decades, Titan boosters have provided unflagging medium and heavy launch capacity for critical military payloads.

38 Evolution of the Inertial Upper StageW. Paul DunnThough initially conceived as a short-term program, the Inertial UpperStage played a critical role in ensuring U.S. access to upper orbits and beyond.

43 The Launch Verification ProcessE. J. TomeiAn impartial and comprehensive system review verifies the flight-worthiness of a launch vehicle and instills confidence in ultimatemission success.

From the Editors

The launch vehicle community is in themidst of a historic transition. The di-verse launch systems that served thecountry’s defensive and scientific

needs for decades have reached the end of theiractive service life. One by one, these heritagesystems are being phased out and supplanted bya new generation of Evolved ExpendableLaunch Vehicles. With the recent inaugurallaunches of these EELVs, the U.S. launch com-munity has embarked upon a course of assured,responsive, and economical access to space.

EELV systems represent the immediatefuture of U.S. space launch activities, but theytrace their roots to programs that began morethan 40 years ago—to the ballistic missile andspace-race efforts of the early Cold War. Then,as now, Aerospace was essential in helping sys-tem designers meet performance objectives andnational defense priorities. Aerospace made sig-nificant contributions to the Gemini program,solving a vexing problem of rocket oscillation,as well as the strategic ICBM program, helpingto derive the multiple independently targetedreentry vehicle concept. Later, Aerospacehelped convert early missiles to launch militarypayloads into space. Construction of the AirForce launch ranges also benefited from Aero-space contributions.

The full range of Aerospace activities inlaunch vehicle development and certificationwould be too much to cover in a singleCrosslink. Thus, we have elected to focus onhistorical programs for this issue. A compre-hensive discussion of design and analysis tools,engineering expertise, advanced concepts, andtechnical approaches will follow in a future edi-tion. In the meantime, we hope this Crosslinkwill provide useful background and shed lighton the company’s considerable involvementwith the major U.S. space-launch initiatives.

Dear Crosslink Reader,

As this issue goes to press, we mourn the tragic loss of the sevenastronauts who perished aboard the space shuttle Columbia. Theirloss reminds us of the high stakes and human impact of spaceexploration. We extend our condolences to the family members of those who died and to our colleagues at NASA.

William F. Ballhaus Jr., President and CEO

Headlines For more news about Aerospace, visit www.aero.org/news/

2 • Crosslink Winter 2002/2003

Two successful rocket launches in thefall of 2002 inaugurated the AirForce’s Evolved Expendable

Launch Vehicle (EELV) program, the firstnew government-sponsored launch systemin two decades. The Atlas V launched onAugust 21, and the Delta IV rocket lifted offin a spectacular night launch November 20.

In launches from Cape Canaveral AirForce Station, Florida, the Atlas V (belowleft) carried a commercial TV broad-casting satellite into orbit, and the Delta IV(below right) inserted a communicationsatellite in a nearly perfect geosynchro-nous transfer orbit.

“Successful first launch of each EELVsystem establishes the next generationspace launch capability to meet the gov-ernment’s needs for the next 20 years,”said Linda Drake, EELV general managerat Aerospace.

Although these werecommercial missionsfor Eutelsat, the EELVprogram is managed bythe Air Force Spaceand Missile SystemsCenter. The first gov-ernment EELV pay-load, a Defense Satel-lite CommunicationsSystem (DSCS) satel-lite, was scheduled tolaunch aboard a DeltaIV from Cape Canaveralin March. Aerospaceprovided technical sup-port to both initial

EELV Launches

ATitan II G-14 rocket successfullylaunched NOAA-M, the NationalOceanic and Atmospheric Ad-

ministration’s newest environmental satel-lite, from Vandenberg Air Force Base onJune 18, 2002.

After the satellite was carried to a near-perfect position in space, its apogee kick-motor provided final circularization of itsnear-polar orbit 450 nautical miles aboveEarth at an inclination of 98.7 degreesfrom the equator. The satellite will collectmeteorological data and transmit the

launches and launch verification for theDSCS launch.

“Aerospace’s role has grown increas-ingly significant since the program’s incep-tion in 1995,” Drake said. The corporationhas provided technical insight to the AirForce throughout the EELV program de-velopment, assessing system design andqualification, monitoring launch process-ing, and providing launch verification forthe DSCS launch.

The government-industry partnership isdeveloping the next-generation expendablelaunch vehicle to give the country more re-liable, affordable space transportation forthe 21st century through improved oper-ability, significant cost reduction over cur-rent systems, and a standard payload inter-face flexible enough to accommodatechanging mission requirements.

information to users around the world toenhance weather forecasting.

Aerospace, as sole provider of Titan IIlaunch verification and validation for theAir Force, verified that all critical hardware,software, and mission analyses met require-ments for flightworthiness. “The Titan II G-14 processing, checkout, and verificationprocess was exceptionally smooth,” saidRay Johnson, vice president of the corpora-tion’s Space Launch Operations.

Aerospace also had a role in the Titan IIG-4 launch from Vandenberg in January.

Black Box for Spacecraft

In an effort to pinpoint sites where spacedebris will land on Earth, The Aero-space Corporation’s Center for Orbital

and Reentry Debris Studies (CORDS) isworking with the Air Force Space and Mis-sile Systems Center to develop a “blackbox” similar to the flight-data recordersfound on commercial aircraft.

“Data obtained using a black box couldprovide clues as to how changes in materi-als and construction might prevent largepieces of space debris from hitting Earth’ssurface,” said Bill Ailor, CORDS director.

Many spacecraft, or pieces of them, re-turn to Earth. A black box that would sur-vive reentry may one day give researchersinformation about changes in materialtemperatures and loads on spacecraft asthey reenter the atmosphere. The box mayalso help determine the “footprint” or areaof Earth’s surface where debris will fall.

Surviving pieces of varying sizes can bespread over hundreds of miles. Many fac-tors, including atmospheric conditions andthe aerodynamic characteristics of the ob-jects, influence the footprint location.

Bill Ailor, fourth from left, joins the CORDS teamby a 260-kilogram stainless-steel fuel tank thatreturned to Earth after nine months in space.

The mission, known as Coriolis, was spon-sored by the Air Force Space Test Programand carried two experimental payloads forDOD. The first, WindSat, is reportedly thefirst passive sensor to measure ocean sur-face wind velocity. The second, the SolarMass Ejection Imager, is an Air Force Re-search Laboratory experiment to forecastgeomagnetic disturbances.

The Coriolis mission will last for threeyears. Aerospace provided technical over-sight during the spacecraft’s development,payload integration, and testing.

Titan II Launches

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(1 kilogram and under) on virtually anyshuttle flight. Aerospace principal investi-gator Ernie Robinson said that this launchcapability is extremely valuable for low-cost ready access to space by anyone de-veloping technology to picosat scale.

The diminutive satellites are serving aspathfinders for a new capability that mightbecome the standard for conventionalsatellites: autonomous inspection. As envi-sioned by their designers, these inspection

Crosslink Winter 2002/2003 • 3

The Aerospace Corporation played akey role in the recently completedairborne cloud sampling campaign

of the Cirrus Regional Study of TropicalAnvils and Cirrus Layers—Florida AreaCirrus Experiment (CRYSTAL-FACE).

The campaign was part of a con-tinuing interagency effort to betterunderstand the ways in which aero-space propulsion-system combus-tion emissions affect atmosphericchemistry and radiation. Sponsoredby NASA, the CRYSTAL-FACEeffort extends previous joint AirForce and NASA work under theRocket Impacts on StratosphericOzone (RISO) program.

“Preliminary analysis of the datahas provided new insights into thesize, shape, and chemical composi-tion of cirrus and contrail ice crys-tals and how these clouds could af-fect global warming,” said MartinRoss, Aerospace RISO programmanager.

Ross served as co-flight scientist(with Randall Friedl of NASA’s JetPropulsion Laboratory) for high-altitude aircraft WB-57F payloadintegration and operations during

picosats will feature an onboard imagingcapability and other sensors that will en-able them to assess spacecraft damage andprovide rapid feedback to spacecraft oper-ators on the ground, thus helping to ensurecontinuous service to users and optimalspacecraft longevity.

The MEPSI project, or microelectro-mechanical systems (MEMS)–based pi-cosat inspector, calls for incremental ad-vances that will result in autonomous andfully functional inspector satellites com-prising MEMS components, such as radio-frequency switches, gyros, accelerome-ters, and thrusters. The principal payloadaboard the picosats launched December 2consisted of inertial measurement units.During the three-day mission, the picosatstransmitted signals to a ground station atMenlo Park, California, and performed in-ertial measurement exercises.

Space Shuttle Launches Mini “Satellite Inspectors”

CRYSTAL-FACE deployment to Key WestNaval Air Station, Florida, in the summerof 2002. He directed a team of more than100 scientists and engineers operating 27instruments carried by the WB-57F tostudy how high-altitude cirrus clouds are

formed, dissipate, and affect the heat bal-ance of the lower atmosphere.

William Engblom of Aerospace appliedstate-of-the-art computer models to simu-late the flow of air around the WB-57F dur-ing flight in an effort to understand how

aircraft-induced changes in air pres-sure and temperature could influencethe response of instruments carriedby the aircraft. Highlights of themonth-long CRYSTAL-FACE mis-sion included sampling a variety ofthunderstorm-related cirrus clouds,close high-altitude formation flyingwith the NASA ER-2, and samplingof the WB-57F’s own contrail.

More detailed results fromCRYSTAL-FACE will be presentedat the spring meeting of the Ameri-can Geophysical Union in Nice,France. The continuing collabora-tion between the Air Force, NASA,and other agencies under the RISOprogram provides the Air Forcewith important credibility, as wellas engagement with the atmosphericscience community with regard tothe impacts of aircraft and rocket-engine combustion emissions on theatmosphere.

Apair of experimental miniaturesatellites were launched by thespace shuttle Endeavour Decem-

ber 2, 2002, as part of a series of test flightsresearchers hope will result eventually inautonomous “ride-along” spacecraft thatcan be released on command to inspectparent satellites.

Connected by a 15-meter nonconductingtether to facilitate detection by ground-based radar and emulate formation flying,the picosatellites were ejected from aspring-loaded launcher built by The Aero-space Corporation and installed in Endeav-our’s cargo bay. The miniature satellites,which measure approximately 10-by-10-by-12.5 centimeters and weigh only 1 kilo-gram each, were built by Aerospace in part-nership with the Jet Propulsion Laboratory.

The launch demonstrated the capabilityof deploying picosat-scale satellites

A south Florida thunderstorm takes on the classic “anvil” form withclouds composed of ice crystals forming a high-altitude “shield” overthe entire area. A key objective of CRYSTAL-FACE was to investigatethe microphysical and radiative properties of the ice particles thatmake up the shield. The WB-57F extensively sampled the shieldcloud of this system on July 27, 2002.

Aerospace Takes Part in NASA CRYSTAL-FACE Mission

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Independent launch certification is a core competency of The Aerospace Corporation.Aerospace operates as a federally funded research and development center for theUnited States Air Force, and as such, is directly accountable to the Air Force Spaceand Missile Systems Center (SMC) for the verification of launch readiness.

Prior to any launch, Aerospace provides a letter to SMC documenting the results of thelaunch-verification process and confirming the flight readiness of the launch vehicle. Thisletter is not just a formality, but represents the culmination of a long and rigorous assess-ment that draws upon the collective expertise of scientists and engineers within the programoffice and the engineering staff.

A Long HistoryThe Aerospace role in independent launch-readiness verification began with the Mercury-Atlas program in 1960, shortly after the corporation was founded. The program had al-ready suffered two failures, and a complete turnaround in reliability was required beforehuman spaceflight could be attempted. Thanks in part to the risk-reduction techniques de-veloped at Aerospace, the mission was ultimately a success. Similar techniques were laterapplied to the Gemini-Titan launch system and the Atlas space-launch vehicle.

The corporation has applied this process to the design, development, and operation ofseveral hundred launches, including the Atlas, Delta, Inertial Upper Stage, and Titan launchsystem variants. The process has also been tailored to support other government and com-mercial launches, including the Atlas V and Delta IV launch systems being procuredthrough the Evolved Expendable Launch Vehicle program. It has allowed Aerospace toovercome major programmatic and technical challenges ranging from the conversion of themassive Titan II intercontinental ballistic missiles into reliable launch vehicles, to the returnto expendable launch vehicle programs after the loss of the space shuttle Challenger. Thecontributions of the launch verification process to system reliability may be difficult toquantify; nonetheless, government launch programs that include independent design cer-tification exhibit a tenfold reduction of risk as compared with commercial launch programsfor the first three flights.

The Verification LetterTo accomplish the entire spectrum of launch-verification activities requires a cadre of en-gineers with expertise in a wide variety of disciplines, including system engineering, mis-sion integration, structures and mechanics, structural dynamics, guidance and control,power and electrical systems, avionics, telemetry, safety, flight mechanics, environmentaltesting, computers, software, product assurance, propulsion, fluid mechanics, aerodynam-ics, thermal engineering, ground systems, and facilities and operations. These engineersprovide valuable input through all phases of launch vehicle development and operations.This provides the basis for Aerospace’s certification of each mission.

The launch-readiness verification letter that Aerospace delivers to the Air Force pro-vides assurance that all known technical issues have been assessed and resolved and that allresidual launch risks have been assessed in a satisfactory manner. Thus, the mission canproceed with an acceptable level of confidence in launch mission success.

The formal launch verification that Aerospace performs forthe Air Force represents a fundamental part of the flight readiness certification for each mission.Ray Johnson

The Path to Mission Success:The Aerospace Role in Launch Certification

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erospace has a rich history in thedevelopment of the U.S. inter-continental ballistic missile(ICBM) force, and this history

is interesting in light of current events aswell as the insight it provides into the evo-lution of a corporate expertise that waseventually applied to other launch, reentry,and reusable launch-vehicle systems.

Aerospace involvement in this area ex-tends from 1960, when the corporation wasfounded, to 1979, when the last divisionengaged in ballistic missile activities wasreassigned. Those two decades were themost dynamic in the Cold War era. TheCuban missile crisis of 1962, in which theSoviets deployed nuclear missile batteriesin Cuba and threatened to launch them if

the United States attacked the island,heightened tensions to an unprecedentedlevel and increased the urgency of Aero-space work in ballistic missiles. PresidentKennedy’s threat of a U.S. counterstrikeagainst the Soviet Union and Cuba con-vinced Soviet Premier Khrushchev to with-draw the missiles, leading to a long era ofdétente based on the policy of mutual as-sured destruction (MAD).

The evolving Soviet threat involved notjust the development of ballistic missilescapable of intercontinental flight, but alsothe development of reentry vehicles capa-ble of carrying nuclear warheads throughthe atmosphere to the target (the Sovietshad also demonstrated fusion bomb tech-nology in atmospheric tests). Furthermore,

in the late 1960s and 1970s, Soviet missilesystems became accurate enough to raiseconcern about their ability to destroy hard-ened targets in the United States, as did theSoviet deployment of large missiles capa-ble of carrying multiple independently tar-geted reentry vehicles. In parallel, the So-viets were developing antiballistic missilesystems, and in the mid-1960s actually de-ployed long-range interceptor batteriesaround Moscow together with the radarsnecessary to track reentry vehicles at greatranges. It is this series of threats that theU.S. ballistic missile and reentry systemprograms had to address.

Effective deterrence hinged upon themutual certainty that a first strike wouldtrigger a devastating retaliatory strike.

For nearly 20 years,Aerospace played a vital rolein advancing the nation’sstrategic ballistic missile andreentry system capabilities.

Richard A. Hartunian

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The Critical Years

Ballistic Missiles and Reentry Systems:


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Thus, the Department of Defenseneeded to ensure that the U.S. fleetof ICBMs would not only survive anuclear missile attack, but would stilldeliver warheads to their intendedtargets without fail, despite the pres-ence of any Soviet defense system.Accordingly, Aerospace’s develop-mental work in ICBM systems fo-cused on four principal areas: ad-vanced ballistic missiles, survivablebasing systems, advanced reentry ve-hicles, and defense-penetrating re-entry systems.

Advanced Ballistic MissilesThe Atlas liquid-propellant ICBM,declared operational in 1959, was theprimary land-based launch vehiclewhen Aerospace began supporting the U.S.ICBM program. The Atlas was soon joinedby the Titan II, deployed in hardened silos.By the late 1960s, these systems were sup-planted by the Minuteman, a small, solid-propellant missile that would also be de-ployed in hardened silos. Three versions ofthe Minuteman were ultimately developed.

Aerospace contributed to all these mis-sile systems, with particular emphasis onthe Minuteman. Through participation inthe Air Force’s Minuteman EffectivenessEvaluation Group, Aerospace helped iden-tify new or upgraded systems for this mis-sile. The effort covered larger-payload mis-siles, improved guidance, and improvedcommand and control.

Aerospace participated in studies thatled to improvements in the Minuteman II,which had a significantly longer range thanits predecessor. Minuteman II also em-ployed solid-state electronics and was thefirst U.S. ICBM to use decoys in its war-head section. Following these achieve-ments, Aerospace helped develop the pow-erful multiple independently targetedreentry vehicle (MIRV) concept for theMinuteman III. This approach gave theMinuteman a fourth stage (known as a bus)with adequate small motors to maneuveraccurately when separated from thebooster. As a result, each of several reentryvehicles could be directed to different tar-gets. Aerospace’s detailed analysis of thedeployment of three reentry vehicles fromthe missile to different targets establishedthe feasibility of this concept.

In implementation, this meant replacingthe single large reentry vehicle on the Min-uteman II with three smaller reentry vehi-cles on the Minuteman III—a tremendous

force multiplier. This concept was copiedby the Soviets some years later.

At the same time, Aerospace was exam-ining other advanced weapon systems, iden-tifying new system concepts, evaluating thefeasibility of promising ones, performingpreliminary designs, formulating cost andschedules, and supporting preparation of re-quests for proposals for the Air Force.

Aerospace also sought to identify ad-vanced subsystems that would economi-cally improve performance and reliability ofnew and existing ballistic missiles, derivingthe specifications for promising technolo-gies and overseeing contractor activitiesduring the development phase. Importantimprovements were made in areas such asguidance and control, command of missilesystems in the field, and propulsion.

Survivable Basing SystemsGiven the accuracy of Soviet missiles,combined with their high-yield warheads,the U.S. strategic missile community wor-ried that ICBMs housed in fixed sites couldbe vulnerable to a missile attack. Tocounter this threat, Aerospace studied morethan 60 concepts for protecting land-basedICBMs, including the use of mobilelaunchers, superhard silos, and antiballisticmissile systems for silo defense. The stud-ies derived conceptual designs for each ap-proach, assessed the technical risks, andestimated the cost of implementation.

The superhard silo approach providedthe lowest confidence of survival becausean increase in enemy missile accuracywould negate the harder silo. Hardness es-timates for this basing option were derivedusing computer codes developed at Aero-space for analyzing the effects of nuclearblasts on missiles and silos. Defense of silo

fields was considered a better option,though this would really require amobile system because fixed radarsand interceptors would surely be tar-geted by enemy missiles.

The mobile ICBM concept wasdeemed the most viable in terms ofproviding survivability with the high-est confidence. Numerous mobile de-ployment schemes were considered.

For example, one promising candi-date was a system for carrying a mis-sile on a large aircraft, such as the C-5cargo plane, which would scrambleupon warning of incoming missiles (aMinuteman was launched success-fully from a C-5 in 1974 to validatethis concept); such a system, however,

would be costly. Another intriguing ideawas to house missiles on “surface effect ve-hicles,” which are akin to hovercraft. Thesevehicles can move at high speeds and pro-vide off-road capability over some terrain.Although studies showed the feasibility ofthis approach and the systems were defined,no development took place. A similar con-cept that received funding envisioned a fleetof small missiles on mobile carriers thatwould travel throughout the country, on oroff road. The missile was developed suc-cessfully, and the transporter was nearingcompletion, but the program was canceled.

Other proposals included carrying mis-siles and launch equipment on barges onthe Great Lakes or other bodies of water;burying missiles in deep holes drilled inhard rock mountains or in abandonedmines; and housing a large number ofsmall missiles in silos dispersed through-out the United States (though this raisedconcern that the number of missiles neededwould exceed the number allowed underarms limitation treaties).

The most effective approach arosethrough Aerospace studies in 1966 of anew missile system, WS 120A, conceivedas the successor to the Minuteman andplanned as a major deterrent for the late1970s and beyond. The WS 120A wouldbe a large missile packed with 10 to 20reentry vehicles (this range encompassedthe eventual Peacekeeper MX). The WS120A basing study proposed deploying themissiles in superhard silos, at least 10times harder than Minuteman silos. Op-tions were designed for additional missilesin off-road mobile and defended modes. Asecond study in 1969 included deceptivebasing of mobile missiles.

Artist’s conception of a reentry vehicle passing through the atmo-sphere. The sharp, conical shape is a legacy of the work done bythe Advanced Ballistic Re-Entry Systems program in the 1960s.

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Aerospace’s early work in ballistic mis-siles was conducted through two divi-sions—the Missile Systems division andthe Reentry Systems division. The Mis-sile Systems division had three subdivi-sions: Advanced Minuteman, AdvancedSystems, and Advanced Subsystems.

The Advanced Minuteman group in-vestigated short- and long-term im-provements to America’s land-basedICBM operational force. This group di-rectly supported the Air Force’s Minute-man System Program Office throughparticipation in the Minuteman Effective-ness Evaluation Group. Aerospace as-sisted studies by the Air Force and itsprimary contractor, TRW, that led to im-provements in the Minuteman II andpaved the way for the powerful multipleindependently targeted reentry vehicle(MIRV) for the Minuteman III.

The Advanced Systems group pro-vided a focal point for development ofadvanced weapon systems. The groupidentified and evaluated promising sys-tem concepts, performed preliminarydesigns, formulated cost and sched-ules, and helped prepare requests forproposals for the Air Force.

The Advanced Subsystems groupsought to identify subsystems that wouldeconomically improve performance andreliability of ballistic missiles. Importantimprovements were made in areas suchas guidance and control, command andcontrol of missile systems in the field,propulsion, and basing. In addition, thegroup conducted extensive research onthe effects of nuclear blasts on silos andmissiles, including shock loads, debrisclouds, and electromagnetic pulse. Theelectromagnetic pulse research helpedto optimize the location and connectionof the rebar in the silos’ concrete andalso provided confidence in the hard-ness estimates for superhard-silo basingproposals.

Aerospace’s Reentry Systems Divi-sion was established in August 1964,when the technical operations at SanBernardino were reorganized to achievefunctional alignment with Air Force activ-ities. The task was to provide generalsystems engineering and technical sup-port to the Air Force’s Advanced BallisticRe-Entry Systems (ABRES) program aswell as the Army’s Nike and Safeguardantiballistic missile programs. Initially,the primary objective of ABRES was tofigure out how to penetrate Soviet an-tiballistic missile systems, which wereundergoing significant testing anddevelopment at the time. In its most ac-tive period, ABRES would routinelyflight-test 10 to 15 small-scale vehiclesand four full-scale vehicles in a year.

Organized Support

These studies led to no immediate devel-opment; however, the Air Force drew uponthe concept of deception in evolving its fi-nal deployment strategy for the Peace-keeper MX. The Peacekeeper basing strat-egy entailed concealing a missile in one ofmany aboveground shelters. These shelterswould not provide the same nuclear hard-ness as a silo, but they would be spaced farenough apart to prevent a single enemywarhead from disabling more than one. Amobile missile carrier with an enclosedcargo compartment would go from shelterto shelter, sometimes with a missile, andsometimes without. The carrier would bedesigned such that no sensor, on theground or in satellites, could discernwhether it held an active missile. The num-ber of shelters would be determined by thenumber of expected reentry vehicles target-ing America’s land-based missiles. Itwould be the supreme shell game. Still, al-though a number of MX missiles wereproduced and deployed in silos, the multi-ple-shelter concept was not employed,

partly as a result of warmingrelations with the SovietUnion.

Advanced Reentry VehiclesImprovements to the missilescreated opportunities for bet-ter reentry systems, whichwas the focus of the AirForce’s Advanced BallisticRe-Entry Systems (ABRES)group. Aerospace providedgeneral systems engineeringand technical direction to thisprogram.

Initially, the objective ofABRES was to derive sys-tems to penetrate Soviet an-tiballistic missile systems,which were undergoing sig-nificant testing and develop-ment at the time. U.S. intelli-gence indicated that theSoviets were developing along-range exoatmosphericsystem based on an early-warning radar that would de-tect objects in its threat corri-dor and cue a second radarthat tracked them with suffi-cient accuracy to launch along-range interceptor.

One obvious way to coun-teract such a system would

be to minimize the reentry vehicle’s radarcross section (the amount of electromag-netic energy reflected back to the radar).That way, the reentry vehicle would avoiddetection until it was much closer to thetarget. The smaller cross section wouldalso make it easier to design credible light-weight decoys.

A relatively sharp nose cone would re-duce the radar cross section substantially,compared with the large, blunt-nosed re-entry vehicles of the prior era (which actu-ally needed a blunt nose to slow their de-scent through the atmosphere to minimizeheating). Moreover, a sharp cone-shapedmissile would maintain a high velocity allthe way to the ground, making it more dif-ficult to intercept.

On the other hand, the smaller internalvolume of the slender cone called for inno-vative warhead design and miniature multi-purpose fuses. More important, the tremen-dous heat rate and pressure on the smallnose radius demanded new materials,many of which hadn’t been developed and

Aerospace helped develop the powerful multiple independentlytargeted reentry vehicle (MIRV) concept for the Minuteman III.


flight-tested for this sort of application. Infact, on some vehicles, the nose tip ablated(burned away) and exposed interior com-ponents to excessive heating; on others, itablated asymmetrically, which caused thevehicles to deviate from course.

The ABRES team attacked this problemvigorously, conducting extensive groundtests and flight tests of various nose-tip ma-terials and designs. Eventually, researchersbegan to understand the phenomenology

and could implement corrective measures.Since then, the nose tips have performedwith great success.

Program efforts then turned to anotherproblem of trajectory perturbations, whichwere having an adverse effect on impact ac-curacy. These perturbations were linked tothe spin or roll that is intentionally inducedto stabilize the vehicle as it travels throughthe exoatmosphere. As some reentry vehi-cles traversed the atmosphere, the roll rateslowed or completely stopped, while forothers, it increased to levels above thepitch/roll stability threshold. In both cases,the vehicles strayed from their intended tra-jectories.

As with the nose-tip problem, extensiveground and flight tests helped identify theproblem, and, as before, remedies werefound and implemented. With the fixes inplace, reentry vehicles were no longer amajor contributor to the total accuracy er-rors of U.S. ICBM systems.

The new sharp-coned reentry vehicle,designated Mark 12, became the warheadof choice for the Minuteman III and wasdeveloped by the Minuteman program of-fice. Because three Mark 12s fit on onelaunch vehicle, they presented a significantchallenge to a potential antiballistic missilesystem, which would have to deploy threetimes as many interceptors. In fact, theABRES program later designed a smallerreentry vehicle that could be packed in

groups of seven aboard the Minuteman III.Such a system was tested in flight and de-clared ready for deployment. Moreover, inanticipation of a larger, more accuratelaunch vehicle than the Minuteman III (i.e.,the MX), the ABRES team also designedand developed a larger reentry vehicle ca-pable of even greater accuracy. Known asthe Advanced Ballistic Reentry Vehicle, itcould be delivered singly on a MinutemanIII or in groups of ten on the larger Peace-keeper MX. The Advanced Ballistic Reen-try Vehicle was deployed on both the oper-ational Peacekeeper and the Navy’s TridentII ballistic missiles—a significant achieve-ment of the ABRES program.

These efforts could not have succeededwithout the help of cutting-edge scientificresearch at Aerospace. Although all thetechnical disciplines made significant ad-vances, two areas in particular—fluid dy-namics and materials science—made newdiscoveries and developments with wide-spread applicability.

For example, Aerospace researchers de-veloped new numerical techniques to solveproblems of hypersonic flow and heat trans-fer, including the effects of chemistry andablation of the reentry-vehicle surface.Also, in studying the implications of chang-ing the shape of the nose, Aerospace devel-oped testing and analysis procedures thatcould be used to analyze the flow aroundaircraft control flaps and the 3-dimensionalheat-transfer environment around vehiclestraveling at angles of attack.

Other areas of inquiry included radio-frequency propagation through ionizedboundary layers, chemical and ionizationreaction rates and byproducts of wake-quench chemicals and air at high tempera-tures, and measurement of the aerodynam-ics and ablation rates of candidatematerials for nose tips in hypersonic andarc-jet tunnels. Aerospace also devised alightweight roll-control system for reentryvehicles that was later demonstrated byABRES. In regard to advanced materialsfor nose tips, heat shields, and antennawindows, Aerospace provided a quick-reaction failure-analysis capability, includ-ing critical nondestructive testing tech-niques to ensure the quality of materials onreentry vehicles. Research into the high-temperature properties of carbon andgraphite gained national recognition.

Penetrating Missile DefensesDefense penetration programs progressedin tandem with research and developmentof ballistic reentry vehicles. The idea wasto provide a number of options for neutral-izing both current and anticipated Sovietantiballistic missile systems. The ABRESprogram developed and tested many meth-ods for penetrating such a defense.

One such method, designed to counterlong-range exoatmospheric defenses, usedexoatmospheric chaff to confuse Sovietantiballistic missile systems. This chaffwas composed of thin metallic dipoles ofthe proper length to absorb and reflect theenergy of the Soviet radars, which wouldregister only a series of opaque “clouds,”hiding the reentry vehicle in one and thethird stage in another. The first design to beflight-tested for Minuteman II showed seri-ous problems, and ABRES was asked to de-velop a solution. Time was critical, becausethe U.S.S.R. was deploying its antiballisticmissile system around Moscow. Within afew months, successful flight tests wereconducted, and a nine-cloud system was de-ployed on the Minuteman II. These flight

Flight test of the Advanced Maneuvering Reentry Vehicle in early 1980. The path of the reentry vehi-cle is the upper streak of light, with the booster tanks immediately below. Lights from the KwajaleinAtoll in the Pacific can be seen in the lower right corner.

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demonstrations prompted the Soviets tocancel their system around Moscow be-cause they realized they would have to usenine interceptors to destroy one reentry ve-hicle.

Compared with the Minuteman II, theMinuteman III permitted a more straight-forward method of chaff deployment. Thefourth stage of the Minuteman III couldmaneuver to different places and drop off abundle of chaff at each, such that all chaffclouds would look like they were going tothe same target. The Minuteman II neverhad that capability, so cans of chaff had tobe fired off of the third stage to the rightpositions—a much tougher job.

To penetrate a layered (exoatmosphericand terminal) defense, ABRES focused ona maneuvering reentry vehicle. This vehicle

would be coupled with anearly-reentry decoy, whichwould remain viable downto the altitude at which thereentry vehicle could ma-neuver. Researchers deter-mined that the extremelyhigh lateral g forces that themaneuvering reentry vehiclecould pull would be morethan sufficient to evade theterminal interceptors.

The first maneuvering ve-hicles tested were large flap-based units, three of whichwere successfully flight-tested over the Pacific in thelate 1960s. Vehicles thatused reaction jets to maneu-ver were also considered,but design studies and windtunnel data indicated thatthe simpler flap arrange-ment could perform all themaneuvers required. Threefull-scale flap-based vehi-cles were flown over the Pa-cific Ocean in 1973–1974,followed by three success-ful preprototype flight testsof the Advanced Maneu-vering Reentry Vehicle in1981. The vehicle was de-clared operational for theMinuteman III or the MX.

The success of the Ad-vanced Maneuvering Reen-try Vehicle was made possi-ble in part by its innovativeguidance system, a small

nuclear-hardened inertial platform thatcould achieve the same accuracy as a bal-listic reentry vehicle even after experienc-ing high-level accelerations. Eight yearshad gone into the development of this guid-ance platform, and its introduction washighly significant. Whereas guidance sys-tems for ballistic missiles can weigh wellover 100 kilograms and only have to with-stand acceleration up to 10 g’s, the guid-ance system for the Advanced Maneuver-ing Reentry Vehicle could weigh no morethan 13–18 kilograms and had to retain ac-curacy after experiencing g forces morethan an order of magnitude higher. Theearly design employed small gyros and ac-celerometers in a small, hardened, gim-baled platform, which was immersed in aliquid to relieve the g force loads; however,

this arrangement generated thermody-namic and chemical interactions among theelectronics, instruments, and liquid. Theseproblems were eventually resolved, and thesmall hardened inertial platform achievedits performance goals, providing a modelfor future development.

End of an EraThe Air Force, with Aerospace concur-rence, transferred its ABRES program toTRW in 1979, ending an era of Aerospaceparticipation in ballistic missile develop-ment. Still, the expertise developedthrough this program continued to producebenefits. Many Aerospace engineers andscientists applied their new tools and ex-pertise to evolving missile-defense andlaunch-vehicle programs. Indeed, many ofthese ICBMs were themselves convertedinto space launch vehicles, with Aerospaceassistance. Future investigations intoICBM modernization will no doubt buildupon the success of the early ICBM devel-opment program, which owes part of itslegacy to Aerospace.

Postscript and AcknowledgementsThis article has covered only a fraction ofall the ABRES system developments andpreprototype demonstrations. The systemsand technology described here are of highimportance; nevertheless, 10 additionalsystems were developed through the pre-prototype stage along with considerableother critical technologies. The ABRESprogram was a team effort involving theAir Force, Aerospace, 57 contractors, othergovernment agencies and laboratories, andother nonprofit organizations. The largeU.S. lead in reentry systems was clearlyobserved by Soviet ships in the PacificOcean and surely contributed in somemeasure to the end of the Cold War.

This article draws upon details from alimited-distribution document by Roy E.Fowler and Sanford L. Collins. The authoralso thanks Robert F. Clauser for clarifyingAerospace’s participation in the Minute-man III and Mark 12 decisions and RichardAllen of TRW for information on the SmallMobile Missile program.

Further ReadingThe Aerospace Corporation, The AerospaceCorporation: 1960–1970 (Times Mirror Press,Los Angeles, 1970).

The Aerospace Corporation, The AerospaceCorporation—Its Work:1960–1980 (Times Mir-ror Press, Los Angeles, 1980).

The Minuteman II had a much longer range than its predecessorand was the first U.S. ICBM to use decoys in its warhead section.

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s NASA’s Project Mercury con-cluded its final flight in May1963, America’s future successin the space race was by no

means assured. Although all of the pro-gram’s major goals had been accom-plished, an enormous amount of work stillneeded to be done before any attemptcould be made to send an American to themoon—which was, at the time, the ulti-mate goal of the U.S. space program.Moreover, the United States was still lag-ging behind the Soviet Union, which hadalready completed a successful two-manflight in 1962 and sent the first woman intospace, cosmonaut Valentina Tereshkova,the following year.

To bridge the gap between the ProjectMercury flights and the planned Apollomoon landing, in December 1961 NASAannounced plans for a series of flights car-rying two astronauts using modified Mer-cury capsules. NASA planners had consid-ered such an interim program, named

Mercury Mark II, as early as 1959, butreached no clear consensus as to what itsmajor goals should be. By the time RobertGilruth, director of NASA’s MannedSpacecraft Center, announced the creationof the program at a Houston press confer-ence, the range of possible objectives hadbeen narrowed to three, although many ofthe management and operations detailswere still not clearly defined.

The Genesis of GeminiThe first objective was to achieve ren-dezvous and docking of two vehicles in or-bit and to maneuver the two spacecraft us-ing the target vehicle’s propulsion system.The second was to complete long-durationflights of up to two weeks. These objec-tives were chosen primarily because oftheir direct application to the upcomingApollo missions. A third objective was todevelop a means of landing the returningspacecraft on an airstrip in the UnitedStates, though this objective was latershelved after several tests of the proposed

paraglider landing system ended in failure.On January 3, 1962, the Mercury Mark IIprogram was formally designated “ProjectGemini.” The program acquired its newname from the Gemini constellation,which was itself named for the twins Cas-tor and Pollux of ancient Greek mythology.

NASA chose the Titan II ballistic mis-sile to launch the Gemini capsule. TheAgena target vehicle would be launched byan Atlas rocket. The Air Force Space Sys-tems Division (SSD) would serve asNASA’s agent, responsible for the develop-ment, procurement, and launch of majorarticles of flight hardware except for theGemini capsule. Thus, with NASA’s over-all funding and direction, SSD providedthe Agena target vehicle, the Atlas launchvehicle for the Agena, the Titan II launchvehicle for the Gemini capsule, and thelaunch services for all of these. Separatecontractors were selected for the Titan II,its first- and second-stage engines, theAgena, and the Atlas rockets.

The Gemini programbrought two orbitingAmerican spacecraft together for the firsttime—and Aerospacehelped arrange themeeting.

Steven R. Strom

A Stellar RendezvousA Stellar Rendezvous

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A Titan II rocket boosts Gemini 3 into orbit onMarch 23, 1965. This flight, the first with an on-board crew, demonstrated that the Geminispacecraft was qualified for human flight.

The first step would be to reconfigurethe Mercury capsule to support the Geminimission. For example, the cabin needed tobe much bigger to accommodate two astro-nauts while providing them the maneuver-ability needed to perform the planneddocking procedures. The spacecraft con-tractor implemented a number of changesto allow greater pilot control, includingsimplified circuitry, redesigned instrumen-tation, and the addition of rendezvous radarand retrorockets. The Gemini capsuleweighed about 2.5 times as much as itsMercury counterpart, with about a 20-per-cent increase in overall size, but with anapproximately 50-percent increase in inte-rior cabin space. The new capsule nolonger contained an escape tower; instead,ejection seats were built in to provide ameans of emergency escape.

SSD asked The Aerospace Corporationto assume responsibility for general sys-tems engineering and technical directionfor both the Titan II and the Atlas/Agena.Aerospace’s primary responsibilities wereto modify the Titan II to permit pilotedspaceflight and to maintain the Pilot SafetyProgram, which had proved so successfulduring Project Mercury. Additional respon-sibilities included modifying Launch Com-plex 19 at the Atlantic Missile Range toaccept the Gemini-Titan and erecting therocket once it was on the launchpad. AGemini Program Office was established atAerospace in January 1962, just one monthbefore John Glenn completed the firstAmerican orbital flight. The goal was tocoordinate the work that Aerospace wasperforming at both the Atlantic and West-ern test ranges.

Rocket ScienceAt the time of its selection in December1961, the Titan II was not fully operational.Some of the difficulties arose simply be-cause the Titan II was far more advancedthan the original Titan ICBM, and was inmany ways an entirely new missile. For ex-ample, the Titan II was fueled by a hyper-golic fuel-oxidizer combination. These fu-els, consisting of unsymmetrical dimethylhydrazine and nitrogen tetroxide, were insome ways easier to handle and did not re-quire a complex ignition system. Althoughthey were very dangerous in terms of theircombustibility and toxicity, they could bestored at room temperature and preloadedinto the rocket long before flight. The Atlasrocket, which used cryogenic liquid oxygen,did not offer that capability. In addition, the

Titan II generated more than 31,100newtons greater thrust at liftoff than theMercury-Atlas, making it an attractive vehi-cle for the heavier Gemini spacecraft.

NASA intended to minimize modifica-tions of the Titan II, but Aerospace soonrecognized that important changes wouldbe necessary. For example, Aerospace ad-vocated the use of inertial (rather than ra-dio) guidance and successfully argued forbackup circuits for the electrical systems,backup flight controls, a redundant hy-draulic system, and a malfunction detec-tion system. While other proposals nevermade it beyond the analysis stage, thechanges that were incorporated into thelaunch-vehicle hardware were of criticalimportance to the overall program.

One of the most important legacies ofthe Aerospace team was the solution to amajor oscillation problem with the Titan II.These longitudinal oscillations were re-ferred to as “pogo” because they resembledthe motion of a pogo stick. Although thepogo vibrations might be acceptable for anarmed missile, they would certainly pre-vent the astronauts from performing theirin-flight duties, and could even be fatal.Following the initial discovery of thisanomaly during the Titan II’s first test flighton March 16, 1962, Aerospace engineersand other members of the Gemini team re-alized that a solution was needed before therocket could be used.

SSD asked Aerospace to guide the pogoinvestigations. After reviewing the staticfiring data from the previous year, SheldonRubin, a member of the Aerospace techni-cal staff, believed he could solve the prob-lem if he had access to the data of the trans-fer function of the Titan’s engines.Aerospace convinced the Air Force to pro-vide about $1 million to the engine manu-facturer to conduct the necessary measure-ments. After receiving the data, Rubindeveloped an analytical model that solvedthe problem. By the end of 1963, Rubin’srecommendations were fully adopted, andpogo suppression devices were added tothe rocket. Subsequent flights over the nextfive months proved Rubin’s modificationsto be a complete success.

Another important Gemini activity un-der Aerospace direction was the GeminiStability Improvement Program, alsoknown as Gemsip. This program was de-veloped by the contractor as a byproduct ofthe design reviews that were conducted forthe Titan’s first- and second-stage engines,

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out its Mercury Program Office. Followingthe closure of the office that fall, BenHohmann and Ernst Letsch took over di-rection of the Gemini Program Office,which was officially known as the GeminiLaunch Systems Directorate. By this time,the hard work of Aerospace engineers andthe rest of the Gemini team was beginningto yield results, as the performance of theTitan II continued to improve in testlaunches. The first Gemini launch vehicle,GLV-1, was ready for testing in May 1963,but the vehicle was found to have defects,including serious problems with the wiringin the second stage. In July, Aerospace andSSD rejected GLV-1 after a combined sys-tems test revealed numerous problems, in-cluding a lack of documented flight statusfor major components. After a second testin October, GLV-1 was approved and sentto Cape Kennedy to prepare for its launchas Gemini-Titan 1, the first of two sched-uled flights without an onboard crew. Addi-tional problems delayed the launch untilApril 8, 1964, but the flight was a completesuccess for both booster and payload, withthe capsule remaining in orbit for nearlyfour days before reentering the atmo-sphere. Ben Funk, SSD Commander, de-scribed Gemini-Titan 1 as “just completelya storybook sort of flight.”

As the process of approving the Titan IIfor passenger flight continued, Aerospace

received a formal request from SSD to be-gin technical surveillance of the GeminiAgena Target Vehicle (GATV). The targetvehicle was a standard Agena, modified topermit docking with the Gemini spacecraft.

Work on the Agena started relatively latein the program because it was not sched-uled for use until the fifth Gemini mission.Still, early development progressed veryslowly, and the Air Force hoped that Aero-space could help the contractor sort out theproblems. Indeed, SSD sought to alter itsoversight strategy, applying Aerospace’stechnical expertise in all phases of theGemini program that were operated underAir Force contracts. As such, Aerospacewas responsible for monitoring the Agenavehicles from subsystem fabricationthrough testing through prelaunch andlaunch. Portions of the Pilot Safety Pro-gram were applied to the target vehicle, butthe difficulties continued, and the firstGemini Agena Target Vehicle, GATV-5001, was not ready for tests until Novem-ber 1964. From the very beginning of sys-tems testing, the vehicle displayed seriousproblems.

Meanwhile, as Aerospace engineersgrappled with the ongoing difficulties of theAgena, preparations continued for thelaunch of Gemini-Titan 2. Even though itexperienced several near-disasters while sit-ting on the launchpad at Cape Kennedy—

originally as part of the pogo investiga-tions. As a result of these reviews, Aero-space developed a new injector for the Ti-tan II to reduce combustion instabilityduring the second-stage engine’s start tran-sient. This was another serious problemobserved during flight tests and groundtests. The manufacturer realized the valueof an ongoing review process after the in-jector selected by Aerospace prevailed intests over the manufacturer’s proposed in-jector. By the end of 1964, Gemsip had be-come an established program at the manu-facturing plant.

Aerospace also performed a vital “les-sons learned” review with the Titan II con-tractor during the process of approving theGemini launch vehicle for human flight.Aerospace had initiated successful ratingprocedures during the Mercury programfor the Atlas rocket with its Pilot SafetyProgram, so it was only logical that SSDwould ask the corporation to continue withthe Titan II. However, the integrating con-tractor had by now changed. To complicatematters, Titan II parts were manufacturedand designed in Denver, but the actual as-sembly took place in a Baltimore facilitythat had previously manufactured only air-planes. The change of contractors requiredAerospace to assume an active role in vir-tually every step of the Titan II assemblyprocedure and to recommend numerouschanges in manufacturing. These contribu-tions added to the growing reputation ofAerospace as an impartial but vital ob-server and contributor. Ron Thompson,who began his Aerospace career in theGemini Program Office in 1964, recalls,“Aerospace added a second set of eyes andears to provide an independent review. Thisdefinitely caused contractors to be morediligent, and to some degree that legacy re-mains the same today.”

In fact, the contractor’s handbook forGemini launch vehicle employees statedthat, “As part of the Pilot Safety Program,SSD and Aerospace impose stringent re-quirements during the acceptance phase.Hardware is not accepted until SSD andAerospace are convinced that the hardwareand documentation comply with appropri-ate specifications and other contractual re-quirements…. Acceptance is characterizedby a methodical approach and an uncom-promising attitude.”

Fixing the TargetWith Project Mercury wrapping up in thespring of 1963, Aerospace began phasing

Joe Wambolt, Tom Shiokari, and Jim McCurry of Aerospace meet with astronauts Gus Grissom andJohn Young at Cape Kennedy.The meeting took place in March 1965 shortly before the two astronautswere launched on the Gemini 3 craft, which Grissom had dubbed the “Molly Brown.” Left to right: JohnYoung, Jim McCurry, Joe Wambolt, Gus Grissom, and Tom Shiokari.


Ed White demonstrates the Hand-Held Self-Maneuvering Unit to Ben Hohmann and Ernst Letsch ofAerospace and fellow Gemini astronauts prior to the flight of Gemini 4.White later used the device to moveabout in space during the first American space walk, which he performed on June 3, 1965. Left to right:James McDivitt, Ernst Letsch, Ben Hohmann, Jim Lovell, Frank Borman, and Ed White.

space program had now advanced well be-yond the capabilities demonstrated duringProject Mercury. Two additional success-ful missions followed with the launchesof Gemini 4 on June 3 and Gemini 5 onAugust 21. The four-day flight of Gemini 4was especially noteworthy, as it marked thefirst time that an American astronaut per-formed an extravehicular activity. EdWhite’s “space walk” was important formorale, because Soviet cosmonaut AlexeiLeonov had achieved the world’s firstspace walk on March 18. The ability of theGemini team to duplicate this feat such ashort time later meant that the U.S. spaceprogram was rapidly catching up with theSoviet program. Gemini 5, an eight-daymission, demonstrated the spacecraft’s ren-dezvous, radar, and long-duration flightcapabilities.

Gemini astronauts were now ready to trya rendezvous and docking with an Agenacraft. The first attempt was scheduled for1966, but was moved to the fall of 1965 tocoincide with the launch of Gemini 6. Onthe morning of October 25, 1965, theAgena target vehicle (GATV-5002) waslaunched from Cape Kennedy. About twomiles away, astronauts Wally Schirra andTom Stafford were seated in their Geminicapsule awaiting their own launch so thatthey could begin pursuit of the Agena. Inspite of a seemingly perfect liftoff for the

Atlas rocket carrying the Agena, the initialjoy of the flight controllers soon turned toconfusion as they lost contact with therocket just after six minutes into the flight.Radar observers reported several blips ontheir screens, and flight engineers wereforced to conclude that the Agena had ex-ploded over the Atlantic. Just 54 minutesafter the countdown began for Gemini 6,NASA was forced to scrub the entire mis-sion as a result of the Agena failure.

To get the problem-plagued GATV pro-gram back on track, SSD and Aerospaceintroduced Project Surefire in November1965. This initiative, given emergencypriority by SSD, was intended to ensurethe flightworthiness of the Agena targetvehicle. Project Surefire began by conven-ing a symposium of propulsion experts,which concluded, in corroboration of theAerospace analysis, that the vehicle’s useof a fuel lead propellant (i.e., a quantity offuel that precedes the oxidizer into thethrust chamber during ignition) had led toengine failure.

The Agena’s engine would have to be re-designed, and members of Project Surefirewould provide oversight and technical di-rection for this initiative. In one instance,Aerospace engineers prevailed upon themanufacturer to eliminate a lock-in relay inthe pilot-operated solenoid-valve controlcircuitry, which they felt was unnecessaryand could lead to potential problems. JoeWambolt, who moved over to the GeminiProgram Office following his work withProject Mercury, still feels pride in Aero-space’s activities during this time. “ProjectSurefire culminated in the best configura-tion obtainable, from hardware, proce-dural, and performance standpoints. Therewere no further engine failures on GeminiAgena vehicles.” Another benefit of ProjectSurefire was the close working relationshipthat it fostered among NASA, Air Force,Aerospace, and contractor personnel fol-lowing the acceptance of many of Aero-space’s technical recommendations.

A Second TryFollowing the cancellation of Gemini 6,NASA boldly decided to make a second at-tempt before the end of the year; however,rather than launch another Agena, the firstrendezvous would be achieved through adual launch of Gemini 6-A (as the flightwas now renamed) and Gemini 7. Thisjoint mission, which garnered the unoffi-cial nickname “Spirit of 76,” began withthe launch of Gemini 7 on December 4.

including being struck once by lightningand twice by hurricanes—the rocket was fi-nally launched on January 19, 1965. Thissuborbital mission, the final launch withoutpassengers, almost equaled the success ofGemini-Titan 1 and cleared the way forGemini 3, the first piloted launch.

Bold MovesNASA, in danger of falling behind sched-ule, decided to wait just two months beforelaunching Gemini 3, which was nowscheduled for March 23, 1965. Mercuryveteran Gus Grissom and crewmate JohnYoung made up the flight team. Followingthe Mercury tradition of giving officialnames to the spacecraft, Grissom dubbedhis Gemini capsule the “Molly Brown,” areference to the Broadway play The Un-sinkable Molly Brown. He chose the namebecause his Mercury spacecraft, the “Lib-erty Bell 7,” sank shortly after landing inthe Atlantic Ocean. Perhaps becauseNASA officials felt that “Molly Brown”was undignified, Gemini 3 was the last toreceive an official name. Future Geminispacecraft would only receive a numericaldesignation. With only a few minor prob-lems during its three-orbit mission, Gemini3 met all of its major objectives and provedthat the Gemini/Titan II configuration wassuitable for human flight.

The first months of 1965 witnessed twosuccessful Gemini launches, and the U.S.


of Aerospace personnel. “Post-flight analy-sis is probably one of the cornerstones ofour launch-vehicle readiness process thatwe have today for Atlases and Titans.”Aerospace historian Everett Welmers neatlysummarized this discovery: “Careful atten-tion to oscillograph wiggles had preventeda potential disaster.” With the dust cover re-moved, Gemini 6-A was launched on De-cember 15, and the craft achieved ren-dezvous with Gemini 7 six hours after itsflight began. The two capsules came withinone foot of each other during the ren-dezvous operation. The next day, Gemini6-A landed in the Atlantic Ocean, andGemini 7 made its reentry on December 18.Funk sent his congratulations to Aerospacepresident Ivan Getting: “Even though facedwith the disappointment of an abortedlaunch, a perfect countdown and a success-ful launch followed and made possible thisnation’s first rendezvous. Please convey mythanks to all the members of your organiza-tion for their participation in this achieve-ment.” In turn, Getting sent a telegram toBen Hohmann, saying, “The contributionsby you and your staff reflect great credit onThe Aerospace Corporation.”

As a result of the successful modifica-tions made to the Agena target vehicle, onJanuary 16, 1966, GATV-5003 was giventhe green light for launch in conjunctionwith the upcoming Gemini 8 mission.Gemini astronauts had so far demonstratedthat humans could function in space longenough to accomplish a lunar mission andcould maneuver one orbiting spacecraft toachieve rendezvous with another. NASAwas now anxious to perform a dockingwith the assigned target vehicle, as this wasthe final Gemini objective. With the con-clusion of Gemini scheduled before theend of the year, NASA’s Gilruth wroteFunk in February to express his thanks forthe contributions of Aerospace personneland encourage their continued participa-tion. “Aerospace has played a large part inmaking the Gemini Launch Vehicle (GLV)Programs successful to date, and we havecome to respect and depend upon the ser-vices they provide the Government.”

Docking and RollingOn March 16, Gemini 8 was lifted into or-bit carrying astronauts Neil Armstrong andDavid Scott. The first space docking inhuman history went smoothly at first, butthe astronauts soon found themselves outof alignment with their original position.Armstrong and Scott were unable to locatethe source of the problem and believed thefault lay with the Agena vehicle. Once theymanaged to separate their spacecraft, how-ever, Armstrong and Scott found them-selves spinning uncontrollably. Apparently,the fault lay with their own craft. With theastronauts in danger of blacking out andtheir fuel supply running low, NASA or-dered an emergency termination of themission. Armstrong realized that a mal-functioning thruster was the cause of theirgyrations, and the orbital attitude maneu-vering system was shut down. The craftwas stabilized only after the reentry systemwas activated and bursts were periodicallyfired from the small thrusters. Gemini 8made a safe splashdown in the PacificOcean, east of Okinawa, after beginning itsseventh orbit. A near tragedy of major pro-portions had been averted, and the crewhad made the U.S. space program’s firstemergency landing. Despite the problemswith the Gemini craft and the early termi-nation of the mission, the Agena target ve-hicle had performed extremely well in itsfirst in-flight test after the Project Surefiremodifications. The final objective of theGemini program had now been achieved.

Astronauts Frank Borman and Jim Lovellwere scheduled for a 14-day flight, whichwould set a new world record and provethat humans could live in near-zero gravityfor extended periods.

The launch of Gemini 6-A was set forthe morning of December 12. But just onesecond after engine ignition, the launch ve-hicle automatically shut down, and thelaunch was canceled. Soon after Schirraand Stafford were removed from the cap-sule, the launch was rescheduled for De-cember 15, and engineers began searchingfor the cause of the aborted launch.

Aerospace personnel, who were alreadyworking around the clock, helped reviewall the available data. They discovered adrop in oxidizer pressure and argued thatthe oxidizer system should be dismantled.Ron Thompson recalls that “There was re-luctance on the part of the contractor, butthe Air Force insisted on checking out theproblem.” The cause of the pressure dropwas a dust cap that had been accidentallyleft in place between the oxidizer checkvalve and the injector.

Wambolt remembers this data review asa key lesson that still resonates in the work

Astronaut Ed White performs the first American extravehicular activity on June 3, 1965, during theflight of Gemini 4. White was attached to his spacecraft by an umbilical line and a 7-meter tether line,which were wrapped together to form a single cord.

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A Successful CloseDuring the remaining four flights, Gemini9–12, astronauts performed additional ren-dezvous and docking maneuvers with thetarget vehicle and conducted more extra-vehicular activities. The reentry and recov-ery of the Gemini 12 craft on November15, 1966, brought the program to a highlysuccessful close. The list of accomplish-ments was staggering, considering some ofthe early problems that the program hadfaced. Ten passenger flights took placewithin the space of a mere 20 months, andthe entire program came in on time andwithin budget. Astronauts acquired impor-tant experience working in conditions ofnear-zero gravity for extended periods andperformed the U.S. space program’s firstspace walks. Many of the problems of ren-dezvous and docking had been solved, andthe modified Titan II had proved itself as acapable launch vehicle. Invaluable lessonswere learned for the upcoming Apollo mis-sions, and all of this was achieved with a100-percent safety record. In addition, byGemini’s conclusion, the Soviet Union wasno longer the clear leader in the space race.During the nearly two years of Geminiflights, the Soviets failed to launch a singlepiloted mission. The early post-Sputnikyears of humiliation for the Americanspace effort were largely forgotten by thetime the Gemini program ended.

The entire space community made noteof the Aerospace contributions to Gemini.The solid work performed alongside theAir Force and NASA made an outstandingcontribution to The Aerospace Corpora-tion’s legacy of partnership and trust. Fif-teen Aerospace representatives receivedOutstanding Achievement awards from theAir Force for their work with Gemini. In aceremony held at the Manned SpacecraftCenter, NASA presented awards toWambolt, Hohmann, Letsch, J. W. Mc-Curry, Newton Mas, and Leon Bush.Words of praise for the Aerospace teampoured in from around the country, butVice President Hubert Humphrey perhapsbest summed up the nation’s thanks in aletter he wrote to Getting on December 8,1966. “Above all, this Gemini program hasrevealed how a team representing the Fed-eral Government and private industry canwork together and, in so doing, show theworld in an open fashion the vitality andefficiency of our democracy and free enter-prise system. I congratulate you and yourassociates for your contribution to Gemini.

The American people are proud of yourrole and participation.”

AcknowledgementThe author would like to thank JosephWambolt and Robert Yowell for the loan ofphotographs and documents that assisted inthe preparation of this article.

Further ReadingThe Aerospace Corporation, The AerospaceCorporation—Its Work: 1960–1980 (TimesMirror Press, Los Angeles, 1980).

The Aerospace Corporation Archives, IvanAlexander Getting Papers, Collection AC-036.

The Aerospace Corporation Archives, JoeWambolt Oral History Interview (Aug. 2,2001).

S. F. Anderson and J. F. Wambolt, “Gemini Pro-gram Launch Systems Final Report,” The Aero-space Corporation Report No. TOR-1001(2126-80)-3, 1967.

P. Bond, Heroes in Space: From Gagarin toChallenger (Basil Blackwell, Oxford, UK,1987).

“Encyclopedia Astronautica,” http://www.astronautix.com (accessed Sept. 9, 2002).

“Gemini Program Overview,” Kennedy SpaceCenter, http://www-pao.ksc.nasa.gov/kscpao/

history/gemini/gemini.htm (accessed Sept. 9,2002).

I. Getting, All in a Lifetime: Science in the De-fense of Democracy (Vantage Press, New York,1989).

J. M. Grimwood and B. C. Hacker, On theShoulders of Titans: A History of Project Gem-ini (Government Printing Office, Washington,DC, 1977).

G. Kranz, Failure Is Not an Option: MissionControl from Mercury to Apollo 13 and Beyond(Berkley Books, New York, 2000).

R. Lewis, Appointment on the Moon: The InsideStory of America’s Space Venture (Viking Press,New York, 1969).

S. Levine, Appointment in the Sky: The Story ofProject Gemini (Walker and Company, NewYork, 1963).

National Aeronautics and Space Administra-tion, Office of Technology Utilization, GeminiSummary Conference (Government PrintingOffice, Washington, DC, 1967).

National Aeronautics and Space Administra-tion, Office of Technology Utilization, ProjectGemini Technology and Operations: A Chronol-ogy (Government Printing Office, Washington,DC, 1969).

The Agena target vehicle as seen from the Gemini 8 craft. On March 16, 1966, the crew performed thefirst space docking with the Agena, a maneuver that was critical to the success of any future moonmission. This operation was the final major Gemini program objective to be completed.

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Since its founding in 1960, TheAerospace Corporation has main-tained an important presence atboth the eastern launch range at

Cape Canaveral Air Force Station inFlorida and the western launch range atVandenberg Air Force Base in California.Aerospace has provided on-site generalsystems engineering and mission assur-ance for essentially all the boosters, upperstages, and spacecraft launched since thebeginning of the national space program.Each launch range offers specific advan-tages that reflect unique histories, loca-tions, and development priorities. Simi-larly, the Aerospace teams at the east and

west ranges have acquired the expertiseand specialization needed to support thesevery different launch sites.

Eastern RangeAerospace support at the Eastern TestRange began with Project Mercury in Sep-tember 1960. The corporation’s role soonexpanded to include support of the Geminiprogram, which used a modified Titan IIintercontinental ballistic missile (ICBM) tolaunch two astronauts aboard a modifiedMercury capsule (see “A Stellar Ren-dezvous”). With the successful completionof the Gemini program in 1966, the Titanlaunch vehicles became the Air Force’s pri-mary workhorses and the main focus ofAerospace support for the Eastern Range.

An early task for Aerospace was the de-velopment of the Titan Integrate-Transfer-Launch (ITL) system and its associated Ti-tan family of launch vehicles, Titan IIIA,IIIC, and IIIE. The ITL system was de-signed to assemble, check, and integrate themajor components of the Titan IIIC beforethe booster would be transferred to the padfor payload mating and launch operations.The ITL system was conceived by Aero-space, which at the time was responsible forgeneral systems engineering and technicaldirection for the facility design, the ground-systems handling apparatus, the checkoutprocedures, and the launch equipment.

Aerospace participated in all ITL designreviews and oversaw the construction of

A CompleteRange of

Launch ActivitiesThe Eastern and Western

launch ranges have a long andillustrious history—with a few

chapters written by Aerospace.

Joseph F. Wambolt and Jimmy F. Kephart

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the complex (which actually includes twolaunch areas, Launch Complex 40 and 41).Construction on the complex began in No-vember 1962 on “islands” created using5 million cubic meters of landfill dredgedfrom the adjacent Banana River. A majorcontribution was to convince the Air Forceto relocate the site from its planned loca-tion (just east of Cape Canaveral’s southgate) to its present location because rangesafety concerns would force the closure ofthe south gate and road during hazardousoperations and launches.

Aerospace also provided general sys-tems integration and technical direction forthe launch of the Titan IIIA vehicles fromLaunch Complex 20 and for developmentof the Titan IIIC launch vehicle. Titan IIICwas based on the Titan IIIA core vehicle;these IIIA flights were important fordemonstrating that the liquid-propelledcore stages were ready to be mated to thenewly developed solid-rocket motors toform the Titan IIIC and for verifying theviability of the Transtage upper stage.Aerospace also supported the launch ofseveral Defense Satellite CommunicationSystem satellites during this period, fol-lowed by a series of Defense Support Pro-gram launches.

A Shift to the ShuttleAs the decade came to a close, Aerospacecontinued to support development of theInertial Upper Stage (IUS) and to helptransition the Air Force to the space shuttle.

When the first IUS launched in October1982, Aerospace had a team in place thathad participated in the design reviews andearly IUS testing (see “Evolution of the In-ertial Upper Stage”).

Shuttle launches took place at NASA’sKennedy Space Center; Aerospace estab-lished an office there, primarily to ensure asmooth transfer of technology from NASAto the Air Force, which was developing itsown space-shuttle launch capability at Van-denberg. But although Aerospace assistedin the testing and evaluation of the shuttlebased on Air Force requirements, the office

at Kennedy was never directly involved inshuttle processing or launch operations.

Following the first shuttle flight in April1981, NASA and the Air Force beganphasing out expendable launch vehicles.The government encouraged private indus-try to build and operate expendable launchvehicles to deliver commercial payloads,such as communications satellites; theshuttle would serve as the primary launcherfor government payloads. This policyquickly changed after the loss of the Chal-lenger in early 1986, which was joined bythe failures of two Titan IIIs, a Delta, andan Atlas/Centaur, all within a span of 18months. These incidents required extensivefailure investigations and costly correctiveactions before flights could resume. Theyalso showed that no one launch vehiclecould provide the guaranteed access tospace that the nation clearly needed.

Staging a ComebackShuttle operations for Air Force programsceased after the Challenger failure. Withina year, Launch Complex 41 was refur-bished and reactivated to accommodate theheavy-lift Titan IV with its solid-rocketmotor upgrade.

When the Air Force returned to the man-agement of the military expendable launchvehicle programs, Aerospace already had acadre of experienced personnel at CapeCanaveral who had participated in theAtlas ballistic missile development andMercury-Atlas, Gemini-Titan, and Agena

An aerial view of the Integrate-Transfer-Launchcomplex at Cape Canaveral. Aerospace was re-sponsible for overseeing the installation andcheckout of the Titan ground systems at the ITLcomplex. Systems engineers reviewed and ap-proved all ground-systems test procedures thatverified the capability of the handling and testingequipment.They played the same role in the ver-ification of the flight-test procedures and partici-pated in all testing operations.

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The Western Range

Vandenberg Air Force Base is located on the central coast of California, almost midway between San Diego and SanFrancisco. It’s the third largest Air Force Base in the nation,encompassing 98,400 acres. The first military installation onthe site, an Army camp, was constructed in late 1941.Yearslater, the base was handed over to the Air Force, which, in1957, began construction of the infrastructure and launch-pads, beginning with seven Thor ballistic missile launchpads.The first Western Range launch of a Thor missile occurred inDecember 1958. In February 1959, the world’s first polar or-biting satellite, Discoverer I, lifted into space aboard a Thor/Agena from Vandenberg. That same year, Vandenberghoused the first nuclear ICBM to be placed on alert in theUnited States. By June of 1960, the Western Range hadflight-tested 45 ballistic, orbital, and probe launch-vehiclesystems. The Air Force annexed more land at the southerntip of the base in 1966 to construct Space Launch Complex 6for the proposed Manned Orbiting Laboratory, which wasnever completed. The complex is being refurbished to ac-commodate the Delta IV evolved expendable launch vehicle.

The Eastern Range

The Eastern Range launch facility is located at CapeCanaveral Air Force Station on the Atlantic coast of Florida.It’s situated on a barrier island between the Banana River andthe ocean, which provides a natural safety buffer around thelaunch area. The installation provides overwater flight for low-inclination and equatorial orbits and includes instrumentationsites along the Florida coast that support suborbital launchesand mobile air and sea launches. The facility encompasses15,800 acres, bordered by more than 23 kilometers of oceancoastline and nearly 20 kilometers of river shoreline. TheEastern Range headquarters are located at Patrick Air ForceBase, about 33 kilometers to the south. The base was estab-lished by the Navy in 1940 to house antisubmarine patrolplanes during the second World War. In 1948, it was trans-ferred to the Air Force for use as a joint long-range provingground. The first missile launch, a German V-2 equipped witha second stage, occurred in July 1950. The first U.S. orbitingsatellite, Explorer 1, was launched from Cape Canaveral inearly 1958. The first Atlas V evolved expendable launch vehi-cle blasted off from the Cape in August 2002.


space launches as well as Atlas facilityconstruction and other pad conversions.

This staff was later augmented by expe-rienced Atlas engineers from Vandenberg.The Atlas/Centaur facility conversion wascompleted in 1991, and the first militarylaunch took place the same year. The Aero-space Atlas team provided general systemsengineering and integration support formilitary launch operations and third-party

oversight of commercial launch vehicleprocessing. Many of these contributionswere indeed significant. For example, fol-lowing Centaur propulsion failures on twocommercial Atlas vehicles, Aerospace de-termined that the problem could have beencaused by a leaking cool-down check valvethat allowed the ingestion of wet air intothe Centaur’s turbo pumps during the boostphase. This theory was verified by an Atlas

investigation team, and no similar Centaurfailures occurred after the proposed fix wasimplemented.

As for the Delta launch vehicle, theAerospace staff at Cape Canaveral gainedinvaluable experience observing the fledg-ling commercial Delta program, whichprepared them for the accelerated GPSlaunches in the early 1990s. The GPS satel-lites were originally intended to fly on thespace shuttle, so Aerospace had a large taskin ensuring that the transition to the DeltaII could support the mission.

Continued EvolutionAfter a period of contraction, the aerospaceindustry appeared to pick up in the mid-1990s, and more defense contractorssought to expand their presence in the po-tentially lucrative but risky commerciallaunch market. These contractors pressedfor more autonomy, and in response, theDepartment of Defense (DOD) began toshift its procurement strategy, grantinggreater control and greater responsibility toprimary contractors. The Evolved Expend-able Launch Vehicle (EELV) was one re-sult of this priority shift. The idea was toacquire launch services (rather than hard-ware) on a vehicle owned and operated bythe contractor.

Aerospace involvement was expected tobe minimal. Congressional funding cuts inthe 1990s had reduced the Aerospaceworkforce by 30 percent. Following thefailure of a Titan IVA in 1998, the AirForce recognized that a modest level ofsupport would be beneficial. Staffing lev-els at the Eastern Range were raisedslightly in 2000 and have continued togrow each year since then.

Launch Complex 41. The towers have been replaced by a new launch infra-structure to support the Atlas V family of evolved expendable launch vehicles.

More than 90 kilograms of explosives were used to bring down the 90-metermobile service tower and 60-meter umbilical tower at Cape Canaveral’s

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Range-Safety Hazard Analysis

Government regulations impose stringent safety requirements on launch plan-ners. Perhaps that’s why no member of the general public or launch-site work-force has ever been killed in a U.S. launch. The Aerospace Corporation helpsthe Air Force’s Range Safety Offices maintain this admirable record of publicsafety. Examples of range-safety efforts include:Jettisoned-Body Impact-Point Prediction. For all Titan II and Titan IVlaunches, Aerospace performs standard analyses to validate contractors’ pre-dicted impact points for all planned jettisoned objects, including solid-rocketmotors, thrust-chamber covers, payload-fairing sectors, and spent stages.Population Overflight Risk Assessment. Overflight of populated areas car-ries a risk to human safety. If an anomaly brings down a launch vehicle beforeit achieves orbital velocity, people in its path can be injured or killed. Aerospacemaintains a toolkit that can calculate the human safety risk for any trajectory; itcombines detailed trajectory simulations with a comprehensive database ofpopulation density.Sonic-Boom Footprint Prediction. A launch vehicle generates a sonic boom,and certain trajectories can produce focused shock waves that create signifi-cant overpressures. Aerospace has tools to compute sonic-boom footprints forascent trajectories and has provided analyses for Titan IV, Titan II, and Atlas IIlaunches.Near-Pad-Explosion Damage Assessment. Inadvertent or emergency de-struction of a launch vehicle can cause significant damage to nearby struc-tures, possibly even destroying the launchpad itself. Aerospace has performednumerous statistical analyses to quantify the risks resulting from near-pad ex-plosions. The methodology was recently used to evaluate the risk that a hypo-thetical EELV failure posed to neighboring launch facilities. Aerospace investi-gated multiple near-pad failure modes, calculated the probability of damageresulting from debris impact or blast overpressure, and recommended risk-mitigation procedures.


As in the heritage programs, Aerospacequickly earned trust and confidence as a“value-added” EELV contributor. Aero-space has been clearly recognized in thesuccessful program milestones to date, in-cluding the launch of the first EELV,Atlas V, from Cape Canaveral in August2002. The second EELV, the Delta IV, waslaunched from the Eastern Range in No-vember 2002.

Western RangeAerospace engineers were first assigned tothe Western Test Range in support of theclassified orbital Discoverer missions nowknown as the Corona program, whichlaunched the world’s first photo reconnais-sance satellites for the U.S. government.Support for this program began even be-fore Aerospace established a permanentphysical presence at the range.

An Aerospace office at Vandenberg wasofficially opened in 1962 to provide on-site monitoring and support to severalemerging programs, most notably theNike-Zeus antiballistic missile system andthe Satellite and Missile Observation Sys-tem. Aerospace was primarily focused on

an extensive series of Atlas flight tests insupport of the Advanced Ballistic Re-entrySystems (ABRES) program, whichachieved its first Atlas launch in November1964 (see “Ballistic Missiles and ReentrySystems: The Critical Years”). These teststypically involved launching long-rangemissiles over the Pacific toward the Kwa-jalein Atoll to test not only the long-rangecapabilities of the U.S. nuclear arsenal butthe antimissile systems stationed for test-ing at Kwajalein.

Aerospace participated in 81 ABRESlaunches and 52 space launches using re-furbished Atlas ICBMs during a 30-yearperiod. These space launches typically oc-curred at Space Launch Complex 3(SLC-3), which was built for the Air Forcein the early 1960s to launch Atlas D/Agenaand subsequently modified to launch theThor; Atlas E, F, and H; and Atlas II familyof boosters.

The Birth of SLC-6Aerospace personnel additionally began toprovide operational planning and activationsupport to the Manned Orbiting Laboratory(MOL), a near-Earth space station that

Although the eastern and western rangesshare many similarities, each has distinctlimitations and advantages. Two azimuths,35 degrees north and 120 degrees south,represent the space launch limits from theEastern Range. Any trajectory further northor south would send a spacecraft over aninhabited landmass. Thiswould adversely affectsafety provisions for abortor vehicle separationconditions and raise theundesirable possibility thata solid-rocket booster orexternal tank could fall inforeign territory. Althoughit is possible to accesspolar orbits from CapeCanaveral, it would re-quire an energy-expensive“dogleg” flight path,resulting in a significantloss of payload capacity.The opposite is true forVandenberg: Polar orbitsare readily achieved with-out significant safety con-cerns, but equatorialspace launches are

precluded by overflight of the United States(a retrograde equatorial launch—oppositeto Earth’s rotation—would not be advanta-geous because of the greater energycosts). The Western Range, from its incep-tion and throughout its history, has essen-tially been a DOD “war-fighting” asset,

established to conduct research and devel-opment of ballistic and air-defense missilesand to support national defense spaceliftoperations. While supporting the commonrequirement for military access to space,each range has evolved its individual,complementary specialization.

Why Two Ranges?

would let military astronauts conduct exper-iments and reconnaissance for up to 30days. Construction of Space Launch Com-plex 6 (SLC-6) began at Vandenberg inMarch 1966 to prepare for the initial launch.Aerospace served as the general systems en-gineer and technical director for MOL, andas such, played a key role in conceiving, de-signing, and developing the project. Follow-ing construction of SLC-6, a plan was pro-posed to launch seven laboratories fromVandenberg on modified human-flight-ratedTitan IIIM boosters. Five launches—includ-ing one with an onboard crew—wereplanned to begin in December 1969. As aresult of technical problems, schedule de-lays, changing national priorities, and thecost of fighting the Vietnam War, the pro-gram was canceled in June 1969. With itscancellation, the nearly completed SLC-6lay unused for almost 10 years.

Although the MOL program was gone,overall launch vehicle activity at the West-ern Range continued at a busy pace. About30 to 40 launches were completed eachyear—including launches of developmentversions of the Minuteman ballistic missile

Longitude (degrees west)

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Azimuth, degrees35

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263 kilometersAllowablespace launchazimuth

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31

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28

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25

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Azimuth,degrees

Inclination,degrees

263 kilometers

10436

140

201

37

36

35

34

33

32

31124 123 122 121 120 119 118


and Titan II ICBM as well as space launch-ers such as Thor/Agena, Titan/Agena,Titan IIID, Atlas/Agena, and Scout. Aero-space launch operations support concen-trated on Atlas E and F and Titan IIIB andIIID space missions.

In January 1979, the Air Force approveda six-year plan to transform SLC-6 into aspace-shuttle launch facility and assignedAerospace the role of general systems en-gineering and integration. Preparation forthe shuttle would require substantiallymore than just refurbishing and modifyingthe SLC-6 site. Additional infrastructurewould be needed, on both the south andnorth sides of the base. Aerospace providedtechnical direction for development andtesting of the ice-suppression system,sound-suppression system, hydrogen-disposal system, power plant, and waste-water treatment plant (see “The Air ForceSpace Shuttle Program: A Brief History”).The Air Force relocated its Shuttle Activa-tion Task Force from Los Angeles to Van-denberg in 1981; Aerospace established ashuttle office there as well, and onsiteAerospace personnel became directly in-volved in every aspect of the project.

After major construction had been com-pleted and systems installed, the spaceshuttle Enterprise was brought to Vanden-berg and erected to perform form, fit, andfunction tests. This system-test unit—which was transported atop a jumbo jet andnever actually flew in space—marked theculmination of years of hard work by Aero-space, Air Force, and contractor personnel.Its successful test runs paved the way for afully operational Air Force space shuttle.

In October 1985, after an expenditure ofabout $4 billion, SLC-6 and the associatedshuttle infrastructure achieved initiallaunch capability, and a first launch wasscheduled for 1986; however, following theloss of the Challenger, SLC-6 was againabandoned. Enterprise would be the onlyshuttle that SLC-6 would ever see.

Resurrecting the TitanThe Air Force refocused its attention on theTitan 34D. The catastrophic failure of a Ti-tan 34D shortly after liftoff from SLC-4Estarkly illustrated the risks of adding solidrockets to launch vehicles. Following thisincident, Aerospace recommended that thelaunch control center be moved to a safedistance more than 25 kilometers away.

On the East Coast, Launch Complex 41was being readied to receive the Titan IV,and DOD saw the need for a similar

capability at Vandenberg to handle largeand heavy payloads. Aerospace was askedto assist in the construction, activation, andlaunch of the Titan IV vehicles.

The Air Force determined that modifica-tions to the Titan III launchpad at SLC-4Ewould be the cheapest and fastest way toget the Titan IV up and running. To speedup the process, it was decided that Titan IIIsystems and equipment would be reusedwhenever possible. This turned out to be abad decision.

The first significant challenge involvedthe reuse of the mobile service tower andthe supporting foundation. The old mobileservice tower could not be enlarged to ac-commodate the Titan IV. This late revela-tion caused the Air Force to reevaluate itsmanagement approach; it increased Aero-space support and formed “Design TigerTeams” staffed with Aerospace and con-tractor personnel. Aerospace was present atall critical design decision points and pro-vided both technical and operational inputsto the Air Force. The contractor submittedthe facility design criteria and payload re-quirement document in September 1986.Aerospace participated in all upgrades anddelineated important lessons learned fromsimilar facility modification projects.

According to a new modular construc-tion plan, the mobile service tower wouldbe built in sections at a facility in Oregon,

shipped by barge to Vandenberg, trans-ported to SLC-4E, and erected using jack-ing towers. At the same time, SLC-4Ewould be modified to receive the mobileservice tower modules. The steel umbili-cal tower would be erected, foundationwork completed, and the underground util-ities and cabling installed. Aerospace par-ticipated in the daily and weekly planningof these activities and supported develop-ment of the ground support equipment de-sign, which proceeded in parallel with thelaunch complex modification.

This effort involved the design of thecommand and control interfaces betweenthe Titan IV vehicle and the ground sup-port systems, including the propellant,pneumatics, electrical power, environmen-tal controls, and control software. The Ti-tan Flight Readiness Plan, developed byAerospace, was the first readiness plan forspace launch vehicles without an onboardcrew. It was patterned after the successfulMercury and Gemini Pilot Safety Pro-grams and specified both continuous andmilestone requirements for Titan launchvehicle processing. It became the govern-ing document for Titan processing andwas subsequently adopted for other spaceprograms as well.

The development of the Titan IV launchcapability at Vandenberg included severalother major infrastructure improvements

Aerial view of a Delta II rocket prior to liftoff at Space Launch Complex 2 in Vandenberg. The Delta IImedium-lift launch vehicle is used to launch Global Positioning System satellites as well as civil andcommercial payloads into low-Earth, polar, geosynchronous transfer, and geosynchronous orbits.

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capability was achieved in September1997, and the first Atlas IIAS left the padin December 1999, carrying NASA’s4850-kilogram, $1.3 billion Earth Observ-ing System satellite. The secondAtlas IIAS success followed in September2001, with the launch of a classified NROpayload. Operations of Atlas II facilities atSLC-3 are scheduled for closeout in 2003.Another NRO mission is scheduled formid-2003; the fate of the facility after thatlaunch has not yet been determined.

In 1994, the Air Force leased out SLC-6to a contractor interested in testing a newsmall launch vehicle. The first launch at-tempt in August 1995 failed to place itspayload into orbit, but did accomplish thefirst successful launch from SLC-6 afternearly 30 years and several major programefforts. Following three successfullaunches, the program was moved to theKodiak Launch Site in Alaska.

Soon thereafter, SLC-6 was againleased out, this time for the Delta IVEELV program. Transformation of thecomplex began in 2000. In addition tomodifications to the launch site, a newhorizontal integration facility was built aswell as a new operations control centerwithin the existing remote launch controlcenter on the north side of the base. Aero-space participated in all design reviewsand provided the Air Force acquisition of-fice with detailed insight into activationactivities. With this effort, the Aerospacefield site engineers at Vandenberg—liketheir counterparts at Cape Canaveral—aretransitioning to the era of EELV and planto support the first West Coast EELVDelta IV launch in 2003.

ConclusionDuring the course of 50 years, the two testranges have conducted more than 4000major launches—including 123 at Vanden-berg in one year alone. As the early periodof intensive research and developmentwound down, the ranges continued toserve the nation’s ballistic missile devel-opment program and expanded their rolesin civilian and commercial space. Over theyears, the two ranges have hosted everymajor launch vehicle program in the his-tory of the U.S. space program. Aerospaceprovided technical support for more than1100 launches during its 40 years at theranges, including Thor, Atlas, Delta, andTitan launches; all U.S. passenger space-flights; and launches of the Scout, Pega-sus, and Taurus rockets.

of generating requirements; incorporationof lessons learned during the constructionand modification of SLC-4 and LaunchComplexes 40 and 36 at Cape Canaveral;and active government involvement in thedesign, construction testing, activation, ac-ceptance, and contract closeout activities.Aerospace played a significant role in thiseffort by providing systems engineeringsupport. The new acquisition methodologyrequired close collaboration between thegovernment and contractor, with Aero-space providing programmatic and techni-cal assistance. Cross-functional productdevelopment teams (the precursor to mod-ern integrated process teams) were estab-lished to develop the SLC-3E ground sup-port systems during the design phase.

In the course of modifications, contrac-tor crews dismantled and removed an ex-isting 64-meter mobile service tower andumbilical mast, built a new tower and maston top of a launch services building, andmodified the services building itself. Othertasks included installation of a heating/ventilating/air-conditioning system andvarious physical security facilities, as wellas expansion of the complex’s fuel storageand loading systems. The resulting SLC-3E provides unprecedented launch andsatellite vehicle access and processingcapabilities, with a protected working en-vironment for its crew. Initial operating

beyond the SLC-4E modification. Majorupgrades and specialized command andcontrol equipment were added to the re-mote launch control center to monitor theprelaunch processing and launch activi-ties. Aerospace provided support to the AirForce for all facilities during these criticaldevelopments. Initial launch capability forthe Titan IV at SLC-4E was declared inOctober 1990.

Facility UpgradesAlso in 1990, SLC-6 got a new assign-ment, and Aerospace again assisted theconversion plans. This time, the pad wouldbe used for a Titan IV booster with a Cen-taur upper stage. Development of the so-called Titan/Centaur Launch Complex atSLC-6 progressed through concept evalua-tion and preliminary design; however, theAir Force terminated construction in early1991, citing insufficient launch require-ments to justify the expense.

In 1992, the Air Force decided to up-grade SLC-3E from an Atlas I to an At-las II site to provide medium-lift launchcapability for surveillance, communica-tions, and exploratory satellites. Affectedby the end of the Cold War and increasedcommercial launch services competition,the Air Force implemented a partneringprogram for management and concurrentengineering. This included increased gov-ernment participation early in the process

Space Launch Complex 6 at Vandenberg during renovations for the Delta IV launch vehicles. Thelaunch table was demolished down to the concrete and a new launch table and fixed pad erector wereinstalled. Other work included removal of extraneous appendages from the access tower, which wasconverted into a fixed umbilical tower, and removal of platforms in the mobile service tower.

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The Air Force Space Shuttle Program:A Brief History

On January 1, 1986, the maidenflight of the Air Force spaceshuttle program was just sixmonths away. This flight, mis-

sion 62-A, would mark the beginning ofthe Air Force’s shuttle launch service fromVandenberg Air Force Base in California.The crew—which included Edward “Pete”Aldridge Jr., then Secretary of the AirForce—was completing preflight trainingat Johnson Space Center in Houston,Texas. The space shuttle Discovery had ac-complished its latest mission in August1985 and was being serviced at KennedySpace Center in Florida prior to its ship-ment across the country. The external tank,which carries the fuel and oxidizer for theorbiter’s main engines, was being certifiedin the checkout facility at Vandenberg, andthe solid-rocket booster segments were inprestack processing at the solid-motor fa-cility. The first payloads were nearly set togo, pending final integration. Vandenberg’sflight-hardware processing facilities were

ready, and Space Launch Complex 6(SLC-6), where the space shuttle wouldlaunch, was nearing the end of its opera-tional readiness testing. Meanwhile, Aero-space personnel were wrapping up theirtraining at Kennedy Space Center, JohnsonSpace Center, and Vandenberg to supportlaunch operations. Among its many firsts,the launch of mission 62-A was to be thefirst human spaceflight into polar orbit.

A Long RoadThese final preparations marked the culmi-nation of a long and intense developmentprocess that included extensive Aerospacesupport. In fact, the Air Force space shuttleprogram dates back to 1971, when the firstconceptual studies concerning payload ca-pability, upper stages, and launch siteswere initiated. The Air Force began thesestudies in concert with NASA, but each or-ganization had somewhat different priori-ties. NASA, for example, was most con-cerned with planetary exploration andscientific missions using satellites inserted

in equatorial orbits. The Air Force, on theother hand, needed to launch critical de-fense and reconnaissance satellites, prima-rily into polar orbits.

Aerospace participated in early studiesthat showed a West Coast launch site forAir Force missions would be needed tocomplement NASA’s East Coast launchsite at Kennedy. Launch-site studies in1974 led to the selection of SLC-6 at Van-denberg, which was well situated forlaunching classified satellites into polar or-bits. The complex had been built in 1969 tolaunch the Air Force’s Manned OrbitingLaboratory, but was never used because theprogram was canceled before first flight.By modifying the existing structures onthis site, the Air Force hoped to save$150 million in construction costs.

These cost savings never materialized.Instead, the launch complex went throughan extensive series of redesigns to satisfychanging requirements. Some of thesechanges reflected new Air Force mission

The Air Force had high hopes for its West Coastshuttle complex. But despite years of preparation,this state-of-the-art facility never saw a shuttlelaunch.E. J. Tomei

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requirements, while others arose to meetchanges in the space shuttle itself, whichwas still evolving in response to NASAtesting, which was proceeding in parallelwith SLC-6 construction.

Aerospace oversaw facility design stud-ies that led to the unique features of SLC-6needed for Air Force missions, such as a se-cure payload processing facility within 300meters of the launchpad. Aerospace wasresponsible for developing system andfacility specifications, supporting contractorselection, evaluating designs, developingactivation plans, and overseeing the final

construction and activation testing of SLC-6and other facilities for flight hardware pro-cessing, control, and crew operations.

Special attention and analyses werenecessary to adapt the existing site to thespecial requirements of the space shuttle.These included small-scale test programsand extensive analyses of liftoff loads anddynamics, ice formation, launch vibro-acoustics, orbiter handling and space shut-tle assembly, flight crew emergencyegress, sonic booms, and hazards to theclosely spaced facilities and surroundingenvironment.

Groundbreaking WorkModification of the abandoned SLC-6 forspace shuttle operations began in January1979. A small contingent of Aerospace en-gineers was stationed onsite from the startof construction; a larger complementwould follow afterward, when the entireprogram office would be moved from LosAngeles to the launch site at Vandenberg.

Most of the refurbishment focused onthe main launch complex, though SLC-6itself was not the only challenge. The AirForce space shuttle program also requireda landing strip nearly 5 kilometers longand various specialized facilities—formating and demating the orbiter and its747 carrier aircraft, orbiter maintenanceand checkout, flight crew preparation,logistics and supply, processing the exter-nal tank, refurbishing the solid-rocketbooster, and recovering the solid-rocketbooster. Aerospace oversaw the design,construction, activation, and operationalreadiness testing of all these installations,including the commissioning and sea trialsof the naval vessel for retrieving the solid-rocket boosters after launch.

While assisting the facility development,the Vandenberg team also participated inspace shuttle testing at Johnson Space Cen-ter, Marshall Space Flight Center, andKennedy Space Center leading up to thefirst NASA launch in April 1981. Aero-space helped formalize the lessons learnedfrom these efforts, reported them to the AirForce, and ensured that they were imple-mented into the systems at Vandenberg.

Partly because of the location, and partlybecause of the different nature of Air Forcemissions, the new facilities at Vandenberg

Flight crew for the inaugural Air Force space shuttle flight 62-A, planned for Vandenberg Air ForceBase. Clockwise from top left: Edward “Pete” Aldridge Jr., Robert Crippen, Brett Watterson, Dale Gard-ner, Jerry Ross, Mike Mullane, Guy Gardner. Not shown is Randy Odle, who was backup on 62-A.

External fuel tank for the inaugural Air Force space shuttle flight 62-A arriving at the checkout facilityat Vandenberg.

Aft solid-rocket booster segment and pallet(weighing 200 tons) on its state-of-the-art 100-ton elevating and leveling transporter.

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required capabilities that the NASA com-plex at Kennedy did not provide. For ex-ample, SLC-6 had a 4000-ton moveablewind screen standing 70 meters tall to shel-ter the orbiter during mating with the exter-nal tank. Sound suppression was enhancedthrough a 3-meter-diameter undergroundwater system flowing nearly 3.8 millionliters per minute. This water system ab-sorbed the launch acoustics generated bythe rocket thrust and prevented its reflec-tion into the flight systems and payloads. Awater-treatment facility reclaimed nearly1.9 million liters of this sound-suppressionwater, which was contaminated with ex-haust products from the solid motors aftereach launch. A unique hot-gas heating sys-tem powered by a pair of turbofan engineswas used to prevent ice formation on theexternal tank. The payload processing fa-cility (which was designed to handle three4.5 × 18-meter satellites simultaneously)was equipped with state-of-the-art electro-magnetic shielding. A 15-megawatt powerplant provided dedicated power for allthese facilities. The whole complex em-ployed a seismic design capable of with-standing a severe earthquake.

With construction nearly complete, theAerospace program office was transferredto Vandenberg in early 1982 to support for-mation of a site-activation task force. Oper-ational verification testing began in 1984,and a joint NASA/Air Force operations

team was formed, with Aerospace in thelead technical support role for the govern-ment. Facility verification tests using theorbiter Enterprise (an unpowered experi-mental model that was deployed from ajumbo jet, not launched from a launchpad)were completed in March 1985. All sys-tems were go for an auspicious first launchin the summer of 1986.

All Systems StopThat first launch never happened. On Janu-ary 28, 1986, the Challenger accident re-sulted in the death of seven astronauts andthe demise of the Air Force’s space shuttleplans. The White House rescinded its 1982mandate requiring all government pay-loads to fly on the space shuttle and in-structed the Air Force to restart the expend-able launch vehicle production lines. Thespace shuttle facilities at Vandenberg wereonce again abandoned, partly because theinvestigation into the Challenger failure re-sulted in design changes that rendered theshuttle incapable of lifting the satellitesplanned for polar flights out of Vanden-berg. The Aerospace space shuttle programoffice was disbanded, and its personnelwere reassigned to the new expendablelaunch vehicle programs and advancedlaunch studies. The primary payload flewon a later space shuttle mission out of CapeCanaveral; however, the second payload,Teal Ruby, never flew in space. The re-maining DOD shuttle payloads planned forVandenberg were placed on the manifestfor the older Titan 34D and the new Ti-tan IV launch systems. No human space-flight has yet taken place in polar orbit.

Further ReadingP. L. Portanova, “DoD Space Shuttle Opera-tions at Vandenberg Air Force Base Launch andLanding Site,” Proceedings of the AF-SD/Industry/NASA Conference on Mission Assur-ance, June 1983.

The first planned payload for the inaugural Air Force space shuttle flight consisted of five experimentsfor modeling Earth’s upper atmosphere. It is shown in the payload bay of the Columbia, which broughtit into space in April 1991.

Artist’s rendering of Teal Ruby, the second payload planned for the inaugural Air Force space shuttle.This experiment was intended to test infrared sensor arrays for detecting aircraft from space. It wasnever flown in space.

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Space Launch Complex 6

The 125-acre Space Launch Complex 6 (SLC-6), with its threemassive moveable structures, was the major development forshuttle operations at Vandenberg; nonetheless, large-scalefacility construction occurred throughout the base as well as atthe Navy facility at Port Hueneme, California. In fact, 53 majorfacilities were constructed at 14 sites. A chronology of thedevelopment of SLC-6 is pictured here.

SLC-6 as it looked in 1979, just before the start of modificationsfor the Air Force space shuttle. The large mobile service tower inthe right foreground, the exhaust duct in the center, and the build-ings in the distance were all modified for space shuttle use.

Line drawing of an early SLC-6 configuration for the Air Forcespace shuttle, circa 1976. Changing requirements spawned atleast six major design configurations. In early plans, the PayloadChangeout Room (the moveable structure in the left foreground)hoisted the payloads vertically from a staging area below ground.

Artist’s rendering of SLC-6 at the start of construction in 1979. Atleft is the payload staging area, which grew into an abovegroundsecure multiple-payload processing facility of huge proportions.The building was fully hardened to withstand the launch environ-ment despite its close proximity to the launchpad.The mobile Pay-load Changeout Room, located in the center of the drawing, wasmodified to transfer the payloads horizontally instead of verticallyfrom the staging area and also to lift the orbiter and attach it to theexternal tank. Slide wires—to carry the flight crew in baskets fromthe orbiter to an explosion-proof bunker during an emergencyevacuation—can be seen in the middle background.

Artist’s rendering of SLC-6, circa 1982, in its final configuration.This layout shows all three of the massive moveable structures,each weighing more than 4000 tons. The last addition was themoveable windscreen (or Shuttle Assembly Building), used alongwith the mobile service tower to hoist the orbiter from its trans-porter, rotate it to the vertical position, and mate it to the externaltank without damaging delicate interface fittings during gustywinds. The original design used hydraulic arms on the front of thePayload Changeout Room, but this concept was abandoned inlight of new information obtained during NASA space shuttle op-erations. Partially visible at the far left (just above the PayloadPreparation Room) is the Launch Control Center, just 350 metersfrom the space shuttle at liftoff. Plans for a remote control centerwere under way, but it would not be available for the inaugurallaunch.

This photo of SLC-6 in March 1985 shows the space-shuttlestack—consisting of the orbiter Enterprise mated to an externaltank and inert solid-rocket motors—sitting on the launch mount.The Enterprise, a nonflight orbiter used in approach and landingtests, was used to verify the launch complex design. It is now un-der the care of the Smithsonian’s National Air and Space Museum.


The intercontinental ballistic mis-sile (ICBM) and intermediate-range ballistic missile (IRBM)programs progressed rapidly in

the 1950s and 1960s, spurred by the needto establish a nuclear deterrent. But DODrealized that superiority in space would ul-timately prove as important as a long-rangestrike capability. As a result, many of themedium-lift boosters that came from theseICBM and IRBM programs were enhancedto meet the demanding performance re-quirements of space-related missions. Inparticular, many versions of the Thor/Deltaand Atlas boosters were modified to flywith various upper stages, such as theBurner, Agena, and Centaur. The AerospaceCorporation played a vital role in theseearly space-related booster developments,and continues to support the advancementof medium-lift launch vehicle technology.

First FlightsThe first Thor IRBM was launched in Jan-uary 1957, followed by the first AtlasICBM in June. Within a short time, the firstpolar-orbiting satellites—including thevery successful but highly classified Dis-coverer series—were launched using theThor booster and Agena upper stage com-bination. Atlas orbital missions began inDecember 1958—just in time to permit thefirst satellite transmission of a Christmasmessage from President Eisenhower.

By mid-1960, Thor had flown more than90 flights, and various Atlas configurationshad flown 55 times; however, success ratesfor both vehicles barely reached 65–70percent. NASA, newly formed in October1958, teamed with the Air Force BallisticMissile Division to oversee modification of

Medium Launch Vehicles for

Satellite Delivery

Decommissioned as weaponssystems, early ballistic missilesmade a successful transition to the U.S. space program,providing vital medium-liftcapacity for military andscientific missions.

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the Atlas D booster for the piloted Mercuryspacecraft and later the Titan II booster forthe piloted Gemini flights. The Air Forcein turn asked the newly formed AerospaceCorporation to provide general systems en-gineering and integration. Many of theAerospace engineers on the Mercury-Atlasprogram came from the Atlas ICBM devel-opment project. As a result, Aerospace wasable to use its technical expertise to di-rectly influence the success of the pilotedMercury and Gemini missions. Aerospacealso became involved in the Atlas standardlaunch vehicle flights in support of classi-fied Air Force programs.

Upgrading the AtlasWhile the Atlas was achieving notable suc-cess in the spaceflight area, its usefulnessfor purely military applications was com-ing to an end. With the advent of the solid-fueled Minuteman ICBM, the liquid-fueledAtlas E/F vehicles were deactivated asweapons systems in 1965 and shipped toNorton Air Force Base in California forstorage. In the next six years, more than 30of them were flown to support the researchefforts of the Advanced Ballistic Re-EntrySystems program (ABRES), which was

investigating ways to penetrate Soviet mis-sile defenses. As a result of these researchflights, the Air Force Space Test Programdiscovered the economy of these vehicles,and sought to use them for selected scien-tific space missions.

From 1970 to 1971, Aerospace recom-mended several reliability improvementsthat would foster the use of weapon-gradeAtlas E/F boosters for space-related pro-grams. For example, Aerospace pressed forupgrades in electronic part quality, redun-dancy in hydraulic control systems, and ad-ditional environmental testing of criticalguidance components. Other improve-ments included redundant ground guidancecomputers and a greater emphasis on fail-ure analysis and corrective action.

In 1971, the Air Force transferred re-sponsibility for the Atlas E/F assets fromthe Ballistic Missile Division to the LaunchVehicles System Program Office. But con-verting these defensive missiles into safeand reliable space launch vehicles was noeasy task, and Aerospace focused attentionon the need for increased technical over-sight. For example, the decommissionedICBM fleet had been deployed and filled

periodically with propellants as part of mil-itary training exercises. Consequently, theywould need refurbishment and modifica-tion to bring them back to baseline condi-tion. The Air Force implemented a pro-gram to remove the aging Atlas vehiclesfrom storage and refurbish them on an “asneeded” basis. With Aerospace assistance,the Air Force would conduct a formal vali-dation of each booster after the refurbish-ment was complete. Aerospace workedclosely with the Air Force to construct aLaunch-Readiness Certification programfor every mission flown on Atlas E/F, em-ploying all the Air Force systems engineer-ing policies in effect at the time. Essen-tially the same approach is used today onAtlas and Delta missions, including thecomponent evaluation and emphasis onfailure analysis and corrective action.

The user community grew in the mid-1970s, and Aerospace’s general systemsengineering and integration responsibilitiesexpanded to include many missions thatposed unique requirements for integrationand launch vehicle design. The most chal-lenging, for example, was Seasat, whichintegrated an Agena second stage with the

An Atlas IIAS rocket lifts off from Space Launch Complex 3E at VandenbergAir Force Base in September 2001. It carried a national security payload.This was the first Atlas Centaur launched from Vandenberg for the Air Force.

This Atlas E carried a Tiros polar-orbiting meteorological satellite for theNational Oceanic and Atmospheric Administration. It is shown lifting off fromSpace Launch Complex 3W in May 1991.

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Atlas E/F for the first time and flew from amodified launchpad. The Seasat missionwas the heaviest upper stage and satellitecombination ever flown on the Atlas E/F,and it necessitated a new approach to struc-tural and flight-control system design andanalysis. Likewise, early GPS missionsemployed a newly developed two-stagespin-stabilized upper stage, which requiredextensive analysis and testing to ensure

that the separation of the spinning stageswould be stable.

During these years, Aerospace devel-oped an array of tools for independentlyanalyzing loads, controls, trajectories, andenvironments. Three-dimensional loadanalysis was introduced to Atlas for thefirst time. Original plans to launch an occa-sional Space Test Program mission grew toinclude 52 missions, which depleted the

inventory of stored Atlas E/F vehicles (in-cluding several retrieved from museums).The first of these missions was launchedsuccessfully in October 1972. Although 28successful missions were achieved, threefailures involving propulsion prompted amajor technical upgrade of the remaining21 vehicles in 1981, including a completeteardown, rebuild, and hot fire of the AtlasMA-3 engine systems.

STAR 48third-stagemotor

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Attach fitting

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Fairingaccessdoor

Third-stage motorseparation clamp bands

Second-stage miniskirtand support truss

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Conicalsection

Interstage

Wiring tunnel

Fuel tank

Centerbody section

Oxidizer tank

Thrust augmentation solids

Adapter

Exploded view of the Delta II rocket carrying a Global Positioning System satellite payload. The PAM,or payload-assist module, is an upper stage used to finalize spacecraft orbits.

An Atlas E lifts a Navstar/GPS Block I satelliteinto orbit from Vandenberg in October 1985.

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The Atlas, Delta, and Titan II boostersare generally considered medium-liftlaunch vehicles because of their pay-load capacity, though the distinction issomewhat arbitrary. Generally speak-ing, a medium launch vehicle can placea payload of 360 to 6800 kilograms intoa 185-kilometer polar orbit. Smalllaunch vehicles such as Pegasus and

Taurus can lift about 270 to 900 kilo-grams, and a heavy-lift vehicle such as aTitan IV or space shuttle can delivermore than 14,500 kilograms to the sameorbit. Medium launch vehicles generallycost about a third or less than a heavy-liftTitan III/IV.

DMSP, GPS, DSCS, and most re-search spacecraft are sized to meet the

mass, height, and diameter specifica-tions for a medium-class booster. Theprocess of payload/booster integrationis decided in early studies before finaldesign. Given the international competi-tion among launch vehicle providers,this becomes a large effort for space-craft designers.

What Does “Medium” Mean?


The upgrade changes were made to allcritical systems of the Atlas E/F booster,including ground checkout equipment andprocedures. Aerospace initiated a yearlongindependent review to evaluate the changesbeing made to the remaining 21 Atlas E/Fboosters to instill confidence that thosemissions would be successful. In additionto the engine overhaul program, flight-control and guidance systems, hardware,and test equipment were retrofitted withthe solid-state electronics that were beingused in the newly manufactured Atlasspace launch vehicles. The Air Forcefunded this upgrade effort and also formeda permanent reliability improvement pro-gram to allow for the evaluation and imple-mentation of new ideas as the flyoutcontinued. As a result, all 21 of these up-graded Atlas E/F vehicles successfullyplaced satellites into their prescribed or-bits, serving programs and organizations asdiverse as the Defense MeteorologicalSatellite Program, Global Positioning Sys-tem, National Oceanic and Atmospheric

Administration, Space Test Program, andNational Reconnaissance Office. The lastsuch mission was successfully flown inMarch 1995.

Aerospace support for the Atlas E/F re-furbishment and launch program lastedmore than 24 years. The Atlas E/F pro-vided an economical (less than $15 mil-lion) and reliable booster for many re-search and development programs andproof-of-concept test flights.

Priority ShiftsIn 1972, with the end of the space race,President Nixon decreed that the UnitedStates would rely on the partially reusablespace shuttle for routine, reliable, inexpen-sive access to space. This represented amajor shift in the national priority: Nolonger would the United States employ ex-pendable launch vehicles based on theoriginal ICBMs.

With this strategy in mind, DOD andNASA began to launch the last of their ex-pendable launch vehicles and stopped in-vesting in any facilities, infrastructure, and

Cape CanaveralComplex 36B

Booster,sustainer, and1st SRBignition

1st SRBburnout

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1st SRB jettison

2nd SRB burnout

2nd SRB jettison

Booster engine cutoff

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Firstburnprestartevents

Mainenginestart 1

Mainenginecutoff 1

Mainenginestart 2

Mainenginecutoff 2

Centaurfirst burnphase

Centaurparkingorbitphase

Centaursecondburnphase

Collision avoidancemaneuver andpropellantblowdown

EndCentaurmission

Spacecraftcontinuesmission

Orientspin-upandseparatespacecraft

The sequence of events in a typical Atlas Centaur launch. The first solid-rocket booster (SRB)assists the booster and sustainer engines at liftoff. The booster engine cuts off approximately164.7 seconds into the flight and is jettisoned roughly 3 seconds later. The payload fairing is jet-tisoned about 233.5 seconds into flight. The sustainer engine cuts off at about 281.6 secondsinto flight, followed by separation of the Centaur upper stage about 2 seconds later. The Cen-taur’s main engine starts at about 300.2 seconds into flight and cuts off about 307 secondslater. After a coast phase, the Centaur main engine starts up again about 1337 seconds intoflight, and cuts off at about 1423.4 seconds into flight. Spacecraft separation begins about 175seconds afterward.

Payload

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Centaurengines (2)RL10A-4

Liquidoxygen tank

Liquidhydrogen tank

Boostersection

The Atlas II booster was 2.7 meters longer thanthe Atlas I and featured more powerful and effi-cient engines. The Atlas IIAS, shown here,added four solid-rocket boosters to the coreAtlas stage. The Atlas II series has achieved100 percent operational success.


Avionics upgrades, 3-meter-diam. fairing ordnance thrusters, extended air-lit GEMs nozzles

Year

RS-27A main engine, graphite/epoxy SRMs

2.9-meter-diam. payload fairing, 3.7-meter stretch for propellant tank, Castor IVA SRMsNew 2nd stage

Payload Assist Module 3rd stage

Delta redundant inertial measuring systemEngine servo-system electronics package

Castor IV SRMsRS-27 main engine, 2.4-meter payload fairing, isogrid main system

9 Castor SRMs, Delta inertial guidance system6 Castor SRMs

Stretched propellant tankUpgraded 3rd stage

3 Castor II SRMs1.5-meter-diam. payload fairingRevised MB-3 main engine

3 Castor I SRMs

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Revised MB-3main engine and3rd stage

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Delta II7925

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The lift capacity for the Delta family of rockets has increased significantly throughout the years.The latestDelta II configuration features elongated graphite-epoxy strap-on solid-rocket motors (SRMs).

range systems that were not required tosupport the space shuttle. NASA adaptedfacilities developed for the Apollo programto support the space shuttle at KennedySpace Center in Florida, and the Air Forceundertook a $4 billion development pro-gram to build and certify extensive shuttleprocessing and launch facilities at Vanden-berg Air Force Base in California.

The loss of the Challenger in January1986 prompted a total reversal of spacepolicy. President Reagan directed federalprograms to reinstate an expendable launchvehicle capability for all future routinesatellites as well as for DOD satelliteprograms previously on the space shuttlemanifest.

As a result, the Air Force selected theDelta II to launch GPS satellites and theAtlas II to launch Defense Satellite Com-munication System (DSCS) satellites.These high-priority defense payloads,which had been designed to fly on thespace shuttle, were compatible in size andmass with the boost capability of themedium launch vehicles. Moreover, the

This 1989 photo shows the first launch of aDelta II from Cape Canaveral carrying a GlobalPositioning System satellite for the Air Force.

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An Atlas II blasts off from Cape Canaveral inFebruary 1992 carrying a Defense SatelliteCommunications System (DSCS III) payload intoa geosynchronous transfer orbit for the Air Force.

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Delta II and Atlas II represented furtherevolutions and refinements of the originalICBM designs, enabling them to accom-modate these satellites.

Switching Back: Delta II and Atlas IIAcquisition reform wasn’t an official pol-icy in 1988, but the Air Force nonethelesssought to streamline procurement by buy-ing launch services from both contractors.In this way, the Air Force would supportthe contractors’ plans to build launchvehicles to a single standard of quality forNASA, the government, and the resurgentcommercial satellite market.

The strategy would provide the AirForce with an economical price based onlarger production runs while encouragingthe contractors to invest in qualityprocesses and manufacturing facilities.Aerospace was contractually permitted toparticipate in the development decisionsand was charged with determining thelaunch readiness of every DOD-assignedlaunch vehicle as it progressed throughproduction and launch preparation.

Aerospace performed an independentanalysis for each booster-payload configu-ration (such as GPS, DSCS, STP) and didnot repeat the analysis unless a majorchange was made to the launch vehicle orsatellite. These analyses emphasized hard-ware performance evaluation, anomaly res-olution, flight data review, and an extensive“pedigree” evaluation of mission-criticalcomponents.

This pedigree evaluation has since be-come a cornerstone of Aerospace launch-readiness assessments. A tedious and labor-intensive process, it entails an exhaustivebackground check of the manufacture andtest history for more than 200 critical com-ponents. Aerospace engineers familiar withthe design and manufacturing details of theelectronic components, pumps, regulators,engines, valves, and explosive ordnance re-view the critical hardware to ensure that as-sembly and testing of each part was com-pleted in a satisfactory manner.

Thanks in part to this pedigree evalua-tion, the Delta II achieved a remarkablesuccess record for the Air Force, promptingNASA to adopt it for space science mis-sions. In 1992, Aerospace began to conductcomponent pedigree services for NASADelta II missions as well, and still performsthis service, providing confidence that ex-perienced specialists have conductedpainstakingly detailed review of the criti-cal hardware flown on each mission.

By 1992, 13 GPS satel-lites were successfully de-ployed, and the 24-GPSconstellation was com-pleted in March 1994 us-ing the Air Force’s rede-veloped Delta II. Themedium-lift launch vehi-cle program is still compil-ing an excellent trackrecord, with 11 of 11 At-las/DOD launches and 37of 38 Delta II launchesachieving ultimate missionsuccess. The only failureof a Delta II involved oneof the eight graphite-epoxystrap-on solid motors. Thisproblem was particularlypuzzling, because 333 ofthese solid motors had al-ready flown without inci-dent. Aerospace deter-mined that the failure wascaused by undetected dam-age to several layers ofgraphite-epoxy fibers inthe protective case sur-rounding the solid propel-lant. As the protectiveouter layers of graphite-epoxy fibers failed, theability of the motor case tocontain the pressure of theinternally burning propel-lant decreased, eventuallyresulting in rupture. As a result, all motorsare now given an extensive ultrasonic in-spection prior to flight to find hidden dam-age from handling and manufacturing.

ConclusionThe medium class of Atlas, Delta, and Ti-tan launch vehicles has provided military,civilian, and commercial space programswith hundreds of successful missions. By

A Titan II lifts off from Vandenberg Air Force Base in June 2002,carrying a meteorological satellite for the National Oceanic and Atmo-spheric Administration. Aerospace verified that all critical hardware,software, and mission analyses met requirements for flightworthiness.

Evolution of the Atlas

The research and development phase of the Atlas ICBM program producedthree experimental models, Atlas A, B, and C. Three subsequent modelsreached operational status. The first, Atlas D, was a liquid-fueled one-and-a-half-stage missile equipped with radio-inertial guidance and a nuclear warhead.It was stored horizontally above ground in an unprotected launcher. Atlas Efeatured all-inertial guidance, stronger engines, and a larger payload capacity;it was also stored horizontally, but in a semihardened launcher. Atlas F alsoused all-inertial guidance, but these missiles were deployed in underground,blast-protected silos; stored vertically; and raised on elevators for launch. AllAtlas models had a range of approximately 12,000 kilometers.

helping to develop the “best practice”processes now in place, Aerospace made amajor contribution to the ultimate successof these boosters. Applying these reliableprocesses to the new generation of Atlasand Delta evolved expendable launch ve-hicles will extend the remarkable perfor-mance records for these versatile medium-lift boosters.

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The history of the Titan spacelaunch vehicle covers more than40 years and has its roots in theearly age of space rocketry.

From its earliest role as an ICBM, the Ti-tan has evolved through dozens of config-urations to serve diverse military and sci-entific missions. With more than 360launches to its name, the Titan has de-servedly earned a reputation as the work-horse of the U.S. fleet of expendablelaunch vehicles. Aerospace personnelcount among the thousands of dedicatedindividuals who share credit for the Titan’sremarkable long-term success.

The Early ImpetusThe Titan II ICBM was first converted intoa space launch vehicle to support the Gem-ini program (see “A Stellar Rendezvous”).At about the same time, the Air Forceasked the newly formed Aerospace Corpo-ration to evaluate two proposals for launch-ing a piloted orbital glider. The first in-volved a new vehicle using a solid-motorfirst stage with a liquid-powered secondstage; the second was the liquid-poweredtwo-stage Titan II, modified by addingstrap-on solid motors for the initial stage.The Titan II approach won out, and thebooster was renamed Titan III. The AirForce established a system program officein November 1961.

Although the Air Force had not identi-fied any payloads for the Titan III otherthan the orbital glider (which was canceledbefore final testing), it became clear thatfuture payloads would cover a spectrum ofspace needs: reconnaissance, communica-tions, military orbital development sys-tems, satellite inspection and interception,surveillance and early warning, and nu-clear test detection. A modular approach tothe Titan III would accommodate this vari-ety quite well. Indeed, the early Titan IIIconcept would permit at least four configu-rations: the two-stage core vehicle, the corevehicle with a final upper stage, the core

For decades, Titan boosters have providedunflagging medium and heavy launch

capacity for critical military payloads.

Art Falconer

Epic Proportions: The Titan Launch Vehicle

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with solid-rocket boosters for an initialstage, and the core with solid boosters andan upper stage.

The Air Force hoped to achieve firstflight of the standard two-stage core vehi-cle by mid-1963 and a flight of the corewith solid-rocket motors by mid-1964. Ul-timately, these goals proved unreasonable,but they served to expedite the projectstartup. Five major “associate contractors”were selected, including Aerospace, whichwas responsible for general systems engi-neering and technical direction. The “asso-ciate” concept was a departure from theusual “prime contractor” concept andplaced considerably more burden on theAir Force. Aerospace was centrally in-volved in the development of the Titan IIIvehicle and a new launch-site processingconcept called “Integrate, Transfer, andLaunch.” This revolutionary concept wasdriven by the configuration variability ofthe vehicle and the predicted launch ratesas high as 60 per year (see “A CompleteRange of Launch Activities”).

The ABCs of Titan IIIThe first of the Titan III variants—TitanIIIA—consisted of the Titan II core vehiclestrengthened to incorporate a third stage(known as the Transtage). The maidenflight in September 1964 failed when the

Transtage pressurization system malfunc-tioned and the engine shut down prema-turely. Three subsequent test flights weresuccessful, the last in May 1965.

The next Titan III to reach orbit—TitanIIIC—was the first version to use solid-rocket motors to boost the performance ofthe liquid-fueled core vehicle. The solid-rocket motors were the first to use thestacked-segments concept. Aerospace as-sisted their development and qualification.The five-segment solid motors were ignitedfor liftoff and propelled the vehicle through“stage zero” of the flight before the stage-one liquid-fueled engines kicked in, atwhich point the solids were cast off. Thisconfiguration could deliver a payload to ageostationary orbit. Ultimately, 36 TitanIIICs were launched from Cape Canaveral,the first in June 1965 and the last in March1982. The payloads were almost exclu-sively military. Five of these missionsfailed, but three of those failures occurredduring the initial eight-vehicle develop-ment phase of Titan IIIC.

In 1965, the Air Force directed its spaceefforts toward the Manned Orbiting Labo-ratory (MOL), a massive structure thatwould require something larger than a Ti-tan IIIC to reach orbit. The resulting de-sign—Titan IIIM—represented a substan-tial change from the Titan IIIC. Almostevery system was modified or redesignedto meet the increased performance andsafety requirements. This included length-ening the first stage, upgrading the liquid-rocket engines and their propellant-feedsystems, developing a seven-segmentsolid-rocket motor, upgrading the avionics,and installing a new ground checkout sys-tem. Titan IIIM development continued forseveral years, successfully getting throughground tests of the new engines and seven-segment solid-rocket motors; however,MOL was cancelled in 1969 before any Ti-tan IIIMs were produced. Nonetheless,even though Titan IIIM never got to thelaunchpad, its development became thefoundation for many improvements phasedinto future Titan configurations.

Following Titan IIIC into space was Ti-tan IIIB, which looked very similar to TitanIIIA but used an Agena instead of aTranstage upper stage. Of the 57 TitanIIIBs launched from Vandenberg between1966 and 1983, 56 were successful. Yet an-other variation—Titan 34B—used an elon-gated first stage and Agena upper stage in a3-meter fairing. The 34B achieved 11 of 11

successful launches from Vandenberg be-tween 1975 and 1987. Typically, the TitanIIIB and 34B carried satellites into polarnear-Earth orbits.

The Titan IIID—created to deliver evenheavier reconnaissance satellites—had theTitan IIIC core and five-segment solid-rocket motors, but without the Transtage. Ofthe 22 Titan IIIDs launched between 1971and the early 1980s, all were successful.

In a departure from the usual Air Forceoperations, NASA had system responsibil-ity for the Titan IIIE. By adding a Centaurupper stage to the Titan IIID and develop-ing a larger, 4.3-meter-diameter payload

fairing, NASA was able to use the rocketfor planetary exploration. The first launchtook place in 1974. Although it flew onlyseven times, the Titan IIIE made a signifi-cant contribution to planetary science,sending the Viking probes to Mars and theVoyager space vessels to the far reaches ofthe solar system.

In the late 1970s, the Air Force orderedyet another class of Titan III vehicles. Thisversion, called Titan 34D, was to providelaunch services for military payloads untilthe space shuttle became fully operational.The initial order was for seven, but as shut-tle schedules slipped, eight more had to bebuilt for payloads that couldn’t wait. Titan34D employed the high-performance 34B

The Titan II still provides medium launch capa-bility for military payloads. Shown here, a Titan IIlifts off from Vandenberg with a Defense Meteo-rological Satellite Program payload.

The first Titan IIIC was launched on June 18,1965. This was the first Air Force vehicle specif-ically designed and developed as a militaryspace booster. Using two strap-on, five-segmentsolid-rocket motors, this vehicle was capable ofplacing a 1450-kilogram payload into a geosyn-chronous equatorial orbit. Several of the TitanIIIC flights involved multiple-payload missionswith four to eight spacecraft.

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core but with new five-and-one-half-segment solid-rocket motors strapped toeach side. Extremely versatile, the Titan34D could accommodate three differentupper stages—the Transtage, the Agena

(although the Agena never flew on a Titan34D), and the Inertial Upper Stage (IUS).Although Titan 34D provided a bridge tothe shuttle era as intended, it had its shareof setbacks. Three of the 15 missionsended in failure. Nevertheless, Titan 34Dwas considered the military powerhouse ofthe 1980s.

Critical ResponsibilityAerospace’s role as associate contractorduring the early years of the Titan III pro-gram was quite different from its role to-day. In addition to general systems engi-neering responsibility, Aerospace hadtechnical direction authority—meaning itcould issue directives, approved by the AirForce, to the other associate contractors re-garding design, construction, testing, andlaunch. This authority was generally notexercised because a collaborative teamapproach became the mode of operation.

In addition to contractor oversight,Aerospace had several inline functions, in-cluding independent verification and vali-dation of guidance software and vehicleloads, writing the guidance steering equa-tions, developing mission specifications,and “pedigree review” of all critical flighthardware. Aerospace also had technical re-sponsibility for all government-furnished

equipment—such as the command-controlreceivers required by range safety.

The Aerospace contribution to postflightreconstruction of flight data was particu-larly noteworthy. The contractor’s initialanalytical approach was very simple andrisked missing potentially important indi-cators of performance. Aerospace deviseda much more sophisticated model using allsignificant flight parameters. This modelidentified several critical performance defi-ciencies, such as reduced specific impulseof the propulsion systems, incorrect pay-load weight, and a bias in the solid-rocketmotors.

Similarly, Aerospace was intimately in-volved in all phases of testing, from devel-opment through qualification, hardwareacceptance, and systems checkout. Inaddition to developing test requirements,Aerospace witnessed and supported muchof the development and qualification test-ing. All test failures were assessed byAerospace engineers, who would typicallywork concurrently with the contractors toanalyze failures and formulate correctiveactions and recovery plans.

During these years, Aerospace was de-veloping the analytical methodologies,tools, models, and databases it would need

Launch summary for the Titan family. More than 360 Titans have beenlaunched within the last 40 years. Overall success rate exceeds 86 per-cent. Discounting the early Titan ICBMs, the success rate jumps to more

than 93 percent. Key: VAFB—Vandenberg Air Force Base; CCAFS—CapeCanaveral Air Force Station; ICBM—intercontinental ballistic missile; SLV—space launch vehicle. (Source: Lockheed Martin Space Systems)

The first Titan IIID prior to its launch on June 15,1971, from Vandenberg Air Force Base in Cali-fornia. All 22 Titan IIIDs launched between 1971and the early 1980s were successful.

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Titan Launch History Summary

Vehicle model Ordered Built VAFB CCAFS Total Success Failure Success ratelaunched launched launched (percent)

Titan I (ICBM) 163 164 20 47 67 48 19 71.64Titan II (ICBM) 141 141 58 23 81 65 16 80.25ICBM Total 304 305 78 70 148 113 35 76.35

Titan II SLV 14 14 12 0 12 12 0 100.00T-II Gemini 12 12 0 12 12 12 0 100.00TII Total 26 26 12 12 24 24 0 100.00

Titan-IIIA 4 4 0 4 4 3 1 75.00Titan-IIIB 57 57 57 0 57 56 1 98.25Titan-IIIC 36 36 0 36 36 31 5 86.11Titan-IIID 22 22 22 0 22 22 0 100.00Titan-IIIE 7 7 0 7 7 7 0 100.00Titan-34B 11 11 11 0 11 11 0 100.00

Titan 34D 15 15 7 8 15 12 3 80.00T-III Total 152 152 97 55 152 142 10 93.42

Commercial Titan 4 4 0 4 4 3 1 75.00Titan IV 40 39 11 23 34 31 3 91.18

SLV Total 222 221 120 94 214 200 14 93.46

Grand Total 526 526 198 164 362 313 49 86.46


to provide totally independent assessmentsof every technical aspect of Titan capabili-ties and performance. This foundationgrew and improved as new technologiesand requirements were introduced.

Rebirth of a TitanBy the mid-1980s, the Titan programseemed to be reaching the end of its usefulservice life. DOD was moving its pay-loads to the space shuttle manifest, andonly about a dozen Titan missions re-mained. Still, some DOD decision makersquestioned the wisdom of putting all theireggs in one basket, and sought somemeans to complement the space shuttlecapability, at least in the short term. Thus,in 1985, the Air Force placed an order for10 so-called complementary expendablelaunch vehicles, or CELVs. The name re-flected their status as a supplement orbackup to the space shuttle. Ten rocketsrepresented a rather modest expansion byTitan standards, and so a “going out ofbusiness” mentality persisted among pro-gram managers. This was especially truein terms of Aerospace’s involvement. Al-though Aerospace launch verification wasto continue through the last Titan mission,Aerospace support for CELV was limitedto source selection. After contract award,there were very limited plans to engageAerospace further.

The Titan 34D provided the startingpoint for the CELV. The 3-meter-diameterpropellant tanks were lengthened to holdmore fuel, and this enhancement in turndrove more upgrades to the liquid enginesto increase thrust and burn time. The 34Dfive-and-one-half-segment solid-rocketmotors were replaced with seven-segmentstacks, first proposed for the Titan IIIMyears before. To be compatible with shuttlepayload capacity, the Titan payload fairingwas increased to 5.1 meters in diameter.The CELV would include a Centaur upperstage and launch exclusively from CapeCanaveral.

With the loss of the Challenger in 1986,DOD payloads were taken off the spaceshuttle manifest. CELV was renamed TitanIV, and the 10-vehicle contract was ex-panded to 23. For a while, Titan IV becamethe sole heavy-lift launch vehicle for themilitary. With this expanded role came theneed for increased versatility to meet aspectrum of different payload and mission-specific requirements.

Seemingly overnight, the Titan programshed its “going out of business” mentalityand began expanding once again. Theresurgence, coupled with concerns overtwo Titan 34D failures in 1985 and 1986,made it clear to the Air Force that Aero-space’s expertise would be needed to re-cover from the failures and embark on de-velopment, acquisition, and operation ofthe new fleet. Accordingly, the Air Forcecontracted Aerospace for general systemsengineering and integration support. Aero-space would provide fully independentlaunch verification for each Titan mission.

The basic configuration of the Titan IVcomprised a common-core vehicle andsolid-rocket motors; however, thanks to amodular approach, the basic model couldbe configured to accept either the IUS orCentaur upper stage for missions requiringdelivery beyond low Earth orbit. The pay-load fairing would also be modular, andcould be provided in lengths from roughly17 to 26 meters. Launches could take placefrom Vandenberg as well as Cape Can-averal. Five basic Titan IV configurationswere created: two with no upper stages forlaunching satellites into low Earth orbitsfrom Vandenberg, and one with the Cen-taur, one with the IUS, and one with no up-per stage for launches from CapeCanaveral. Lift capability grew to nearly18,000 kilograms for a low-Earth orbit.

The first launch of Titan IV, later namedTitan IVA, took place in June of 1989 from

Cape Canaveral. Eventually, 22 Titan IVAswere launched, the last in August 1998.Only two of these missions failed.

At about the same time that Titan IV wasinitiated, the Air Force decided to convert anumber of deactivated Titan II ICBMs foruse as medium-lift space launch vehicles.From the fleet of 54 deactivated Titan IIs,14 were modified to provide launch capa-bility from Vandenberg into the polar orbitplane. Modification entailed removing thecore vehicle’s warhead interface and re-placing it with a space payload interfaceand a 3-meter payload fairing. The elec-tronics, avionics, and guidance systemswere also upgraded using Titan III technol-ogy. An attitude-control system was addedfor stabilization during the coast phase af-ter second-stage shutdown and before pay-load separation.

To date, 12 of 13 planned missions havebeen successfully completed. Payloadshave included military reconnaissance andweather satellites as well as civil meteoro-logical and imaging satellites. The successof the modified Titan II is especially re-markable considering its use of nearly 40-year-old hardware, designed to 1960s tech-nology but still meeting modern needs foraccess to space.

The Final IVEven before the first Titan IVA waslaunched, the Air Force wanted to upgradeits performance and reliability. Thus wasborn the final member of the Titan family,Titan IVB. Procurement began in 1989with a contract for 28 vehicles (thoughonly 17 were ever built). A new three-segment solid-rocket motor upgrade re-placed the seven-segment units. This up-grade not only provided a 25-percentincrease in payload capability, but yieldeda more reliable stage-zero booster, thanksto the reduction in number of componentsand improvements in manufacturing andinspection techniques. Extensive upgradesof Titan’s electrical and guidance systemswere implemented to replace obsoletetechnology and vintage parts that weregrowing increasingly difficult to procure.Production processes were redeveloped toemploy a “factory-to-launch” approach.The goal was to deliver problem-free hard-ware requiring a minimal amount of assem-bly at the launch site. The manufacturingwould be kept at the factory, and the launchsite would only be used for the final stack-ing, checkout, countdown, and launch.Accordingly, the checkout equipment was

The first Titan 34D launching two DSCS II satel-lites from Cape Canaveral on October 30, 1982.The 34D was a “stretched” version of the 34Bcore vehicle and incorporated two five-and-one-half-segment solid-rocket motors. This vehiclewas used with several upper stages, payloadfairings, and guidance configurations.

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I1959

II1962

Gemini1964

IIIA1964

IIIB1966

34B1975

IIIC1965

IIID1971

IIIE1974

Comm III1989

34D1982

IVA1989

II SLV1988

IVB1997

Titan history Activeconfigurations

modernized and automated to improve ve-hicle health checks during the final assem-bly and countdown.

The end result was the Titan IVB stand-ing 61 meters tall, with a lift capability of21,680 kilograms to low Earth orbit and5760 kilograms to geosynchronous orbit.Its maiden launch in February 1997 usedan IUS to deliver a payload for the DefenseSupport Program. Of the 12 Titan IVBlaunches so far, all but one (the 1997Cassini mission to Saturn) carried criticalmilitary satellites. Of these 12 launches, 11were successful. The sole failure, in April1999, was followed by seven successes in arow. (Another anomalous mission in April1999 was attributed to the IUS and is notcounted as a Titan IVB failure.) Five TitanIVB missions remain, four from CapeCanaveral and one from Vandenberg, allwith DOD or NRO payloads.

Aerospace functioned as a full partnerwith the Air Force and contractors in veri-fying that each Titan IV and modified TitanII was ready to launch with acceptable risk.Independent analyses and evaluations per-formed by Aerospace contributed to im-proved risk assessment and sometimes evenfailure avoidance. A good example was theevaluation of a proposed change to the Ti-tan IV stage-two engine-nozzle skirt. Thenozzle’s ablative liner was made of asbestosphenolic impregnated with resin, and an al-ternate resin was being proposed. Aero-space became concerned about the ther-mostructural capability of the new skirtbecause of uncertainty regarding resinproperties at high temperatures. These con-cerns were key in driving the need todemonstrate that the skirt was structurally

sound under engine hot-fire conditions. Theskirt failed the test and was declared unsuit-able for flight. A new skirt using quartz phe-nolic in place of asbestos phenolic was nextproposed. Aerospace was instrumental indeveloping the testing requirements to qual-ify the new design. Subsequent hot-firetests proved its suitability.

In spite of the dedicated efforts by thecontractors, Air Force, and Aerospace toverify that each launch vehicle was flight-worthy, Titan missions sometimes ended infailure. In these instances, Aerospace wasalways part of the return-to-flight process.For example, the first failure of a Titan IVA

occurred in August 1993: About 100 sec-onds into flight, the casing of one of thesolid-rocket motors burned through, andthe vehicle was destroyed. Through exten-sive image analysis, graphical modeling,and analytical work, Aerospace identifieda suspect segment of the solid-rocket mo-tor. A subsequent search of build recordsshowed that a defect may have been intro-duced by a procedural change many years

A Titan IVB blasts off with a Milstar communica-tion satellite. The Titan IVB can boost payloadsweighing 17,600 kilograms into a low Earth polarorbit, 21,680 kilograms into a low Earth equato-rial orbit, or more than 5760 kilograms into ageosynchronous orbit.

In April 1999, this Titan IVB launched a DefenseSupport Program missile-warning satellite fromCape Canaveral, Florida. Although the Titan per-formed successfully, the Inertial Upper Stagesuffered an anomaly and failed to deliver thesatellite correctly into orbit.

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earlier. A void in the restrictorbond required repair, which in-volved a knife cut from bore tocase. Testing showed that under-cutting into the propellant couldresult in flame propagation atmotor ignition and burning at thewall until the thin insulation wasreached. Aerospace performedgrain analysis and assisted intesting that supported the theory.Segments with restrictor repairswere removed from the fleet, andall subsequent solid-rocket mo-tors have been successful.

Aerospace was also involvedin the analyses that followedtwo other Titan launch failures.In August 1998, a Titan IVAwas destroyed when a radicalsteering maneuver forced thevehicle into an ascent positionbeyond its capabilities, leadingto structural breakup. Months ofinvestigation were required todetermine the cause (most likely an electri-cal short in a wire harness in the secondstage) and formulate a recovery plan. Aero-space handled many portions of the investi-gation solely and separately. Aerospace ex-perts also assumed roles ranging fromcochair of investigation panels to specificanalysis or test tasking. The efficiency ofthis arrangement enabled a return to flightwithin eight months.

The second of these Titan IV failures,the Titan IVB in April 1999, was separatedfrom the first by just one successful TitanIV flight. In this instance, the cause of thefailure was actually known within minutes:An incorrect constant in the control-systemsoftware caused radical roll errors, eventu-ally resulting in a loss of control during theCentaur upper-stage flight. The erroneousconstant resulted from simple human error

(a misplaced decimal point).There were indications of thiserror before flight, but initialconcerns were not adequatelypursued; Aerospace’s traditionalvalidation and verification rolehad been assigned to a sub-contractor under the dictates ofacquisition reform, so Aero-space was not required to checkfor such a transcription error.After the failure, the contractor,with Aerospace assistance, de-veloped a process-proofing im-provement plan that started withsoftware but was ultimately ap-plied to every critical analyticaland test process employed onthe Titan program. Aerospacealso revisited its own software-validation process and devel-oped improved processes tocheck mission software morerigorously. Thanks, in part, tothese efforts, the basic Titans

were returned to flight within a few weeksand the Centaur upper stage within a fewmonths.

Titan in ReflectionBy any standard, the Titan program hascompiled a formidable track record, deliv-ering into orbit hundreds of satellites thatwere ultimately able to perform their tasksas required. More than 360 Titans havebeen launched, with a total success rate of86 percent. This figure is especially im-pressive because it includes the TitanICBM (which did not need pinpoint accu-racy to achieve effective deterrence). With-out the ICBMs, the historical success ratejumps to 93 percent.

During every phase of the Titan’s evolu-tion, Aerospace was there to provide in-valuable technical support. By virtue of itsobjectivity and independence, Aerospacecould apply its unique strengths and tech-nical competence in all areas of space sys-tems engineering, design, computationalmodeling, and simulation to establish highconfidence of mission success. The Titan’sfinal launch in a few years will mark theclose of a remarkable chapter in the historyof rocketry and of Aerospace support forthe nation’s most venerable launch system.

AcknowledgementThe author would like to thank Aerospaceretirees Don Moses and John Bauer for theirassistance and guidance during the researchand preparation of this article.

Assembly of the Titan IV core boosters. The manufacturing facility was builtfrom scratch in 1956 and delivered the first Titan ICBM three years later.Thelast Titan core vehicle produced at this facility, a Titan IVB, was delivered in2002. In total, 526 Titans were built—305 ICBMs and 221 space launch ve-hicles. Of these, 148 ICBMs were test-launched, and 214 space launch ve-hicles have been launched to date.

Composite Solid-Rocket Motor Cases—Fred Buechler

After working with the steel-cased solid-rocket motors for the Titan III, 34D, and IVAvehicles for 25 years, Aerospace assisted the development and qualification of thegraphite-epoxy composite solid-rocket motor upgrade. The primary advantages ofthe composite-cased motors included higher performance, lighter spent weight,and greater nozzle control. Higher reliability was also achieved through the use offewer components; the composite version has only two segment joints per motor,as opposed to the eight joints for the segments and closures on the steel model.

Aerospace contributed substantially to the design of the composite-to-metal jointas well as to the propellant-grain design for the forward, center, and aft segments.Aerospace personnel participated extensively in all seven qualification motorfirings. Working alongside the contractor and manufacturer, Aerospace providedexpertise in the development of a comprehensive nondestructive evaluation pro-gram for the upgraded motor components. When production or qualification prob-lems were encountered, Aerospace joined with the contractors to resolve theissues and continue processing. All the upgraded propulsion, structural, hydraulic,electrical, and avionics components were checked by Aerospace as part of thehardware acceptance review process. Equally important was the participation ofAerospace during the assembly and testing of the Titan IVB vehicle hardware atthe launch bases.

With 12 of the 17 Titan IVB launches complete, the upgraded motors have flownsuccessfully with predictable and consistent performance.

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The Inertial Upper Stage (IUS) is ahighly redundant and ground-commandable launch vehicleused to insert payloads into

higher orbits than would be possible withjust a primary booster. Throughout theyears, the IUS has evolved to become anintegral part of America’s access to spacefor both military and civilian sectors.

Initial StudiesThe evolution of IUS began in 1969, whena presidential directive set in motionNASA and Air Force studies that led to de-velopment of the Space TransportationSystem (STS) and its principal vehicle, thespace shuttle. As part of the early STS def-inition, NASA and the Air Force jointlystudied several concepts for transportingpayloads into higher operational orbits, es-pecially the geosynchronous orbits used bymost communications satellites. Physical

limitations—such as the high propellantmass that would be required—prevent astandard booster from reaching these veryhigh orbits. Rather than build a bigger

booster, NASA and the Air Force focusedon an upper-stage rocket as the most prac-tical method available. Aerospace was inte-grally involved in these early studies, as-sessing the feasibility of cryogenicallyfueled orbit-to-orbit vehicles, piloted trans-fer vehicles, and modifications of existingupper stages such as the Centaur, Delta,Agena, and Transtage.

Based on these studies, NASA decidedon a “space tug”—a reusable transfer vehi-cle that would tow satellites from an orbit-ing space platform to their final operationalorbits. Such a project, however, would takeyears to complete. In the meantime, NASAand the Department of Defense (DOD)agreed to develop what was then called theInterim Upper Stage. This decision fos-tered a series of additional studies—in-cluding many at Aerospace—to determinethe requirements, capabilities, and ultimateconfiguration of this temporary upper

An Inertial Upper Stage during processing for anAir Force mission. The IUS began developmentin 1976. In 1982, it flew its first mission aboard aTitan 34D.

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Evolution of the

Inertial Upper Stage

Though initially conceived as a short-term program,the Inertial Upper Stageplayed a critical role inensuring U.S. access to

upper orbits and beyond.W. Paul Dunn

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stage. In 1975, DOD proposed an expend-able solid-fueled rocket because it wouldcost less to produce than a liquid-fueled ve-hicle. Independently, NASA also settled ona solid-fueled stage after determining that aliquid-fueled stage interfered with STS de-signs and could compromise the safety ofthe flight crew.

Aerospace assisted the Air Forcethrough its source-selection process be-fore establishing a program office in 1976.Several contractors proposed modifica-tions to their existing rocket designs tomeet the requirements of the new upperstage. Shortly before commencement ofthe program-validation phase, however,the Air Force introduced a new require-ment: The IUS must be compatible notonly with the space shuttle, but with theTitan 34D booster as well. The Titan 34Dwas the largest available expendablebooster and was capable of placing largerand heavier payloads into orbit (militarypayloads tend to be more massive thancivilian payloads). This capacity was im-portant because of the competitive posi-tion it offered for commercial access tospace and the security it offered for na-tional defense. The Air Force also wantedto use the upper-stage avionics to guidethe booster through its powered flightphase to improve reliability.

At the end of 1977, NASA abandonedits plans for a space tug, so the IUS pro-gram name was formally changed from In-terim Upper Stage to Inertial Upper Stage(because it used inertial navigation). Theprime contractor was selected, and full-scale development began in April 1978.

Development IssuesAerospace worked to overcome several im-mediate challenges during development.Key requirements included a payload ca-pacity of 2268 kilograms and reliability of96 percent or better, all with minimal im-pact to the STS program. Also, the neces-sary support equipment had to be designed,and unique configurations had to be pro-duced for NASA planetary missions. Nu-merous technical difficulties nearly scut-tled the entire program. Significantproblems occurred in the propulsion sub-system (e.g., case burst, tacky liner, softand cracked propellant, nozzle delamina-tions), in the software (sizing and timing,guidance, redundancy management, failuredetection and correction), and in the avion-ics (space-rated parts, redundancy, testing).Evolving definitions of booster loads andenvironments also threatened develop-ment, as did problems arising in the quali-fication testing of the support equipment.Compounding matters, significant differ-ences arose in interpretations of contract

and specification requirements, and a seri-ous weight-growth problem prompted adrastic weight-reduction program. A Titan-specific interstage and extendable exit conehad to be added to maintain performance,and a destruct system had to be added toensure launch-range safety.

This array of technical problems—cou-pled with various programmatic changes—led to schedule delays, higher costs, and,subsequently, two program restructurings.These delays, in turn, affected other as-pects of the program. For example, theTracking and Data Relay Satellite (TDRS)was to be the first NASA payload for theIUS, and the DSCS II and III communica-tion satellites were to be the first for DOD;however, delays and scheduling conflictscaused uncertainty as to whether STS orTitan 34D would be the first IUS booster.Both would present exceptional challengesfor a first-time launch. Requirements con-tinued to shift and evolve, and the InterfaceRequirements Documents, safety proto-cols, and other procedures had to beworked out for the first time—under con-siderable scheduling pressure. Qualifica-tion testing was still going on in many ar-eas for the STS version, and IndependentReadiness Review Team findings led toseveral “fix before launch” concerns. Alsoduring this period, NASA requirements for

Interstage

Extendable exit cone

Solid-rocket motor

Avionics bay(redundant components)

Thrust vectorcontrol actuator

Solid-rocket motor

Reaction control system

Spacecraft separation plane

Components of the Inertial Upper Stage. The first-stage solid-rocket motorholds approximately 9700 kilograms of propellant and can maintain thrustfor up to 150 seconds.

Workers in the vertical processing facility at Kennedy Space Center inFlorida oversee the lowering of the IUS booster into a workstand for preflightprocessing. The IUS was attached to a Tracking and Data Relay Satellitedeployed by the space shuttle Discovery in July 1995.

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Stage 0 ignition

Stage 1 ignition

Roll to 93 degreeazimuth

Solid-rocket motorseparation

Payload fairingjettison

Injection intopark orbit

Stage I/IIseparation

Titan/IUSseparation

Postseparation

Transferorbit

Startmissionsequence

First stageseparation

First stageignitionand burn

Second stageignition and burn

Spacecraftseparation

Spacecraftrelease

Complete spacecraft mission

IUS mission completePost-release

IUS collisionavoidancemaneuver

planetary missions changed: The need formore accurate control dictated a three-axisstabilized configuration, which increasedpayload mass.

Though problematic at the time, thesedemands led to several modifications to the

IUS that now reflect its uniqueness as anupper stage. For example, the IUS first-stage motor can maintain continuous thrustfor as long as 150 seconds—longer thanany other solid-fueled upper-stage rocketdeveloped for space applications. IUS is

also the most functionally redundant upperstage available, and it is the only one thatcan be commanded from the ground duringflight. To support this ground-commandcapability, Aerospace helped develop anarray of contingency procedures to guide

TVCactuatormotorTVC

actuatormotor

RCSsupply

Thrusters

Thrusters

Structure

Separationdevices

Separationdevices

SRMignition

SRMignition

SRM-1 SRM-2

Batteries

BatteriesTVC

electronics

TVCelectronics

Signalinterface

Signalinterface

Signalconditioner

SignalconditionerComputer

Computer

RIMUchannel 1

RIMUchannel 2

RIMUchannel 3

TT&C

TT&C kit(option)

and command; RIMU—redundant inertial measurement unit; TVC—thrustvector control; RCS—reaction control system; SRM—solid-rocket motor.

System architecture of the Inertial Upper Stage, the most functionally re-dundant upper stage available and the only one that can be commandedfrom the ground during flight. Acronym key: TT&C—telemetry, tracking,

In a typical IUS launch, a primary booster (such as aTitan IVB) powers the initial liftoff from the pad. Within afew minutes, the booster’s first-stage engine falls awayand its second-stage engine kicks in, carrying the systemto a low Earth or “parking” orbit. Soon thereafter, the IUSseparates from the booster’s second stage and assumescontrol for the remainder of the powered ascent. About anhour later, the first-stage IUS solid-fueled rocket beginsfiring. The second solid-fueled rocket motor ignites to-ward the end of the ascent, followed by a coast phase,and finally, separation of the payload. The IUS canhoist a 2268-kilogram satellite into a geo-synchronous orbit or heave a 3628-kilogramspacecraft out into thesolar system.

The IUS measures about 5.18 meters long by 2.9 meters in diameterand has an overall mass of nearly 14,800 kilograms. Two slightly differentversions are available, one for use with the Titan and one for the shuttlelauncher. The IUS first-stage solid-rocket motor holds about 9700 kilo-grams of propellant and generates more than 188,000 newtons of thrust.The second-stage solid-rocket motor holds more than 2700 kilograms ofpropellant and generates more than 80,000 newtons of thrust.

The first-stage motor can maintain continuous thrust for as long as150 seconds—longer than any other solid-fueled upper-stage rocketdeveloped for space applications. Actual duration can be tailored to suitmission requirements.

From Lift to Release: the Stages of a Launch


rapid response to potentialmission anomalies; moreover,the flight operations supportteam, which includes Aero-space personnel, conductssystematic simulation exer-cises to prepare for any even-tuality during launch.

First LaunchesThe inaugural IUS launch,mated with a Titan 34Dbooster and a DSCS II/IIIspacecraft tandem, took placeabout five minutes after mid-night on October 30, 1982, atCape Canaveral Air ForceStation in Florida. Aerospaceprovided technical supportthrough its general offices andon-site launch personnel. Un-fortunately, a loss of teleme-try persisted for much of theflight—not surprising, per-haps, considering how manytechnical difficulties had to be

overcome. Nonetheless, even though fly-ing “blind” to Earth observers, the IUScompleted its mission as planned becauseit was designed to fly autonomously by de-fault, without commands from outsidesources. After later analysis, the telemetryloss was attributed to a leak in the her-metic seal of a switch that routed radio-frequency signals to the IUS transmittingantennas. The leak allowed internal pres-sure in the switch to drop to a level wherecorona arcing occurred and caused switchfailure.

Even with this problem out of the way,the second flight experienced difficultiesthat probably would have ended the mis-sion for any other rocket. When a criticalseal failed, the control system lost its abil-ity to position the nozzle of the solid-rocket motor. The nozzle canted, causingthe IUS to tumble through space alongwith the attached TDRS spacecraft. Thelack of nozzle control was compounded bydisruption of normal automatic missionsequencing as a result of unusually highcosmic radiation. Subsequent groundcommands—possible only with the IUS—succeeded in separating the IUS from theTDRS, but the spacecraft was still tum-bling. NASA was able to use the excesspropellant on the TDRS to stabilize thespacecraft and eventually raise it to the de-sired geosynchronous orbit. Since then,the operational history of the IUS has beenimpressive, with 20 missions experiencingno significant anomalies. The lone excep-tion occurred in April 1999, when the IUSstage-one component failed to separatenormally from its stage-two component.

Aerospace also worked to make IUS asaccurate as it is reliable, supporting a sig-nificant upgrade to the avionics for naviga-tion, control, and guidance in 1999. Toachieve this upgrade, the three originalflight computer and inertial measurementunits were redesigned into one chassis.This upgrade preserved the redundancywhile modernizing the gyroscopic compo-nents from mechanical devices to more re-liable ring laser devices and reducingoverall mass by more than 45 kilograms.The flight software was also upgraded toemploy more modern coding and othermodifications. A single electronics unit,named the Flight Controller, incorporatedall these changes. As a result, the IUS hassince attained its highest level of orbit in-sertion accuracy.

Mechanisms

How do you launch a spacecraft with a 12-meter-diameter antenna via a 3.6-meter-diameter launch vehicle? How does a single launch vehicle support dif-ferent spacecraft firmly enough to withstand launch forces, but gently enough todrop them into their correct orbits with a rotational speed no more than one-sixth of a clock’s second hand? Moving assemblies—or mechanisms—accom-plish critical tasks such as these.

During launch, mechanisms help the launch vehicle shed excess weight. Forexample, many vehicles carry external solid-rocket motors that must be dis-carded once their fuel is used up. Release mechanisms and hydraulic actuatorspropel them away from the core vehicle.

Similarly, a launch vehicle’s internal fuel tanks are shed when their fuel is de-pleted. An explosive charge breaks the connection between a rocket’s stages,then compressed springs and guides help separate the spent stage.

Further into flight, as the atmosphere becomes negligible, the protective pay-load fairing becomes unnecessary, so it gets jettisoned. A continuous explosivecharge or discrete pyrotechnic bolts break the connections between fairingsegments. Then, hydraulic actuators team with open hinges, cams, or othermechanical apparatus to move the segments away from the launch vehiclewithout recontact.

The final separation is the payload release. One method for this is similar toa stage separation, where separation nuts release structural bolts joining thepayload and rocket. Another method uses a clamped-band system, in whichboth bodies possess similar interface rings, and a band is tightened aroundtheir flanges. In this case, a bolt cutter or separation nut releases the band, thusallowing compression springs to impart relative velocity between the bodies.

Critical mechanisms such as these require stringent analysis to ensureproper design and operation. The Aerospace Corporation has developed spe-cialized tools for static, kinematic, and dynamic analyses to predict positions,velocities, accelerations, and reaction forces for multiple rigid and flexiblebodies. These computer-aided simulations model complex, three-dimensionalseparation mechanisms and events to verify that mechanisms will perform as intended.

An IUS carrying a Tracking and Data Relay Satellite moves into aparking orbit following deployment from the space shuttle cargobay before boosting the satellite to a geosynchronous orbit.

NA

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End of an EraThough conceived only as a stopgap meas-ure, IUS became an indispensable part ofthe U.S. space program, achieving severalnotable distinctions. For example, it wasthe first upper stage to be used on the TitanIVA and B vehicles and the space shuttleand the first to provide upper-stage guid-ance for the Titan 34D. A number ofNASA and DOD spacecraft have been car-ried aloft by IUS, including the Galileoprobe, the Chandra X-ray Observatory,and the latest Defense Support Programsatellites.

In 1997, organizational restructuringfolded IUS into the Titan program andended its stand-alone status. The last IUSon the manifest is expected to launchsometime in 2003. This final mission willbring to a close an important chapter in thehistory of space launch.

AcknowledgementThe author would like to thank R. K.Luke, A. R. Shibata, H. Sokoloff, A. E.Goldstein, and G. D. Jensen for their con-tributions to this article.

DSP-16 and the IUSbooster are checkedout in the cargo bay ofspace shuttle Atlantisprior to release.

NA

SA

Inertial Upper Stage Unclassified Flight History

Tag no. Booster Date Payload Notes

IUS-2 Titan-34D 10/30/1982 DSCS II/III 1st IUS; telemetry loss

IUS-1 STS-6/Challenger 4/4/1983 TDRS 1 SRM-2 anomaly

IUS-3 STS-51L/Challenger 1/28/1986 TDRS 2 Shuttle explosion

IUS-7 STS-26R/Discovery 9/29/1988 TDRS 3 IUS return to flight

IUS-9 STS-29/Discovery 3/13/1989 TDRS 4

IUS-18 STS-30/Atlantis 5/4/1989 Magellan Magellan to Venus

Titan IV 6/14/1989 DSP 14 1st Titan IV

IUS-19 STS-34/Atlantis 10/18/1989 Galileo Galileo to Jupiter

IUS-17 STS-41/Discovery 10/6/1990 Ulysses Ulysses to solar Polar orbit

Titan IV 11/13/1990 DSP 15

IUS-15 STS-43/Atlantis 8/2/1991 TDRS 5

STS-44/Atlantis 11/24/1991 DSP 16

IUS-13 STS-54/Endeavour 1/13/1993 TDRS 6

IUS-20 Titan IV 12/22/1994 DSP 17

IUS-26 STS-70/Discovery 7/13/1995 TDRS 7

IUS-4 Titan IV 2/23/1997 DSP 18

IUS-21 Titan IV 4/9/1999 DSP 19 Failed separation of SRM-2

IUS-27 STS 93/Columbia 7/23/1999 Chandra Chandra Observatory



Key: DSCS—Defense Satellite Communications System; TDRS—Tracking and Data Relay System; DSP—Defense Support Program


The Launch Verification

ProcessManufacturing and QualityThe manufacturing process must also bereviewed to ensure that it can produce thefinal design. Quality-control processes arechecked for compliance with standards andrequirements.

After reviewing the results of initial pro-duction, Aerospace provides technical sup-port to resolve problems with manufactur-ing techniques. This support can entailin-plant review of hardware and processes.

Hardware VerificationEven before hardware can be screened fordefects, acceptance test plans and proce-dures must be reviewed to ensure that thetest environments and pass/fail criteria canbe trusted to screen out faulty components.Aerospace responsibilities in this area in-clude witnessing selected acceptance test-ing of critical items and reviewing anomalyreports and corrective actions. Aerospacepersonnel also monitor failure investiga-tions, and, in certain critical cases, aug-ment them with independent investiga-tions, which can include metallurgicalanalyses, material compatibility checks,electronic component testing, and contam-ination assessments.

System Design and QualificationAerospace begins by verifying that overalltop-level performance requirements areproperly supported by lower-level systemsand subsystems. Independent analyses val-idate dynamic loads and clearances, struc-tural margins, thermal protection, and con-trol stability.

At this point, design engineers reviewsystem, subsystem, and component qualifi-cation requirements to ensure that they pro-vide adequate margins. Qualification test-ing is witnessed and documented, and thetest results are evaluated to confirm thatthey meet system requirements. Such thor-ough qualification reviews apply to en-gines, solid motors, ordnance, controls,avionics, guidance, structures, and majorsubassemblies.

Milestone reviews must also be con-ducted, including a system requirementsreview, software design review, prelimi-nary design review, and critical design re-view. Aerospace evaluates any changeswith respect to the qualification baselineand may recommend requalification if thechanges are severe or have been improp-erly implemented.

The process used to independentlydetermine launch system flightreadiness is a capability unique toThe Aerospace Corporation that

has been employed for more than 40 years.It is based on a comprehensive technicalassessment that is thorough in its attentionto detail with total system coverage.

The Aerospace approach to launch-readi-ness verification is unparalleled in itsbreadth and depth. This comprehensive,end-to-end process extends from conceptand requirements definition through flightoperations: It entails the detailed scrutiny ofhundreds, if not thousands, of components,procedures, and test reports; it draws uponindependently derived system and subsys-tem models to objectively validate contrac-tor data; it provides timely review throughfirsthand involvement in all aspects of thelaunch campaign; and it concludes with athorough postflight assessment using inde-pendent analytical tools and independentlyacquired telemetry data to generate usefulfeedback and monitor performance trends.

Following is a brief description of someof the critical activities needed to completethe process for a given mission.

An impartial and comprehensive system review verifies theflightworthiness of a launch vehicle and instills confidencein ultimate mission success.

E. J. Tomei

Mission planning,verification, and

analysis

Softwareverification and

validation

Hardwareverification

Assembly, test,and preflight

readiness

Launch-readinessverfication

Countdownand launchoperations

System designand

qualification

Postflightanalysis

Manufacturingand

quality

This functional flow diagram outlines the primary elements of the Aerospaceindependent launch-readiness verification process. This comprehensive

process extends from concept and requirements definition through flightoperations and includes a postflight assessment using independent tools.


One particularly important task is thehardware “pedigree” review, which fo-cuses on individual components and sub-systems to establish that they were builtand tested according to specification. Thispedigree review includes a check ofquality-assurance documentation to verifythat the manufacturer followed the appro-priate procedures, implemented engineer-ing changes properly, justified any devia-tions adequately, and used valid criteria inselecting new processes or materials. Thepedigree also includes an assessment ofacceptance testing.

Software ValidationEvery space launch requires mission-specific software that contains the instruc-tions needed to get the payload from thelaunchpad to its intended orbit. Aerospaceconducts an independent validation andverification of critical system software, es-pecially pertaining to guidance, navigation,and control.

Validation of the launch system soft-ware typically requires the development ofindependent models and tools. Verificationof flight software involves independentsimulations in two phases using prelimi-nary, then final, data from the dynamicsanalysis and mission design activities.These simulations ensure that program-mers have implemented the correct trajec-tory and navigation algorithms in the auto-pilot software and have properly laid outthe sequence of events to be followed dur-ing launch.

Mission Planning, Verification,and AnalysisA well-built launch system can still fail inits mission if it’s not properly integratedwith its payload. Mission design analysisprovides assurance that the launch systemis capable of delivering the specific pay-load to its planned orbit with sufficientmargin to guarantee mission success. Aero-space performs an independent analysis toverify adequate mission planning for allflight conditions. This involves examiningsystem-level and integration requirements,confirming all mission-specific payload in-tegration requirements to ensure that base-line reliability is preserved and new re-quirements have been met, and ensuringthat all prior flight and test anomalies havebeen adequately resolved.

The mission analysis establishes that theflight trajectory and parameters are opti-mized for the specific payload, satisfyflight and safety constraints, and provideadequate margins for the radio-frequencylink, power, propellant, and consumables.Dynamic loads must be analyzed to verifybooster capability and compliance with theinterface control document. Guidance,navigation, and control performance mustalso be analyzed for acceptable injectionaccuracy and control stability. Emphasis isplaced on new hardware and software ornew applications of established designs.

Other analyses—covering details suchas aerodynamics, thermodynamics, vibro-acoustics, electromagnetic compatibility,

radio-frequency interference, separationclearance, and contamination—verify op-eration within vehicle capabilities and in-terface control document specifications.

Assembly, Test, and Preflight ReadinessAt the launch site, numerous tasks must beaccomplished to prepare for launch. Aero-space assesses these processes to establishthat they adequately support mission readi-ness and satisfy design requirements andoperational constraints. Critical tasks andtests are witnessed and evaluated for com-pliance with requirements and procedures.Particular attention is placed on anomalyidentification and resolution. Aerospacepersonnel support all major launch sitetests and readiness reviews and providetechnical corroboration for the test team.

Launch-Readiness VerificationAssuming all procedures have been prop-erly documented and all test results fallwithin acceptable levels, Aerospace cannow give its launch-readiness verificationto the Air Force’s Space and Missile Sys-tems Center (SMC). This document in-cludes an overview of the launch verifica-tion activities, a listing of independentanalyses and verifications, results of thepedigree review, a synopsis of lessonslearned from similar missions, an explana-tion of anomaly review and resolution ef-forts, and an appraisal of launch-site pro-cessing adequacy.

The assessment culminates in a flight-worthiness determination and certification

Dem

onst

rate

d re

liabi

lity

(per

cent

)

Commercial

Government

1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001Calendar year

100

50

40

30

20

10

0

90

60

70

80

First three flights of new vehicles, as of 2001 – 12 – 31

Government

Commercial

21 / 21 = 100.00%

21 / 31 = 67.74%

Success rateProgram Reliability

96.90%

67.01%

Comparison of early launch reliability performance of government and com-mercial launch programs suggests that the independent design certification

resulting from the launch verification process results in a tenfold reductionin risk. Probability of failure comparison: 33 percent versus 3.1 percent.


by SMC at a meeting known as the FlightReadiness Review. The objective is to en-sure that the primary contractors, Aero-space, the spacecraft program office, andthe launch programs agree that the launchvehicle and payload are ready to begin finallaunch operations.

Countdown and LaunchAerospace personnel are “on-station” dur-ing countdown and launch, supportinglaunch decisions with the knowledge andexperience gained during the launch verifi-cation process. Day-of-launch support alsoentails an independent review of launchplacards, countdown anomalies, deviationsand workarounds, and launch constraint vi-olations. Any anomaly or deviation ob-served until liftoff may result in a reassess-ment of the vehicle’s launch readiness. Ifthe launch is scrubbed, a new flight readi-ness assessment may be required beforethe countdown can resume.

Aerospace personnel also providecountdown and launch support via theSpacelift Telemetry Acquisition and Re-porting System (STARS) room. From thisfacility, launch system technicians haveaccess to a historical flight database viaspecial computer and software tools,allowing independent evaluation of trendsand mission-to-mission performance.

Postflight Analysis and Lessons LearnedAerospace’s responsibility does not endwhen the launch vehicle finally leaves thepad. In fact, some of the most rigorous

analysis happens after liftoff. For example,launch-system flight data are analyzed toindependently assess vehicle performance,identify and assess flight anomalies, andupdate the data archives. Postflight analy-ses and reconstructions are used to performtrend analyses, capture lessons learned,and provide feedback for the next readinessassessment.

Postflight analysis of mission perfor-mance, for example, compares actual flighttrajectory and performance characteristicsto predicted values. Guidance measure-ments are processed to produce a trajectoryprofile and determine stage energy levels.Pressures, temperatures, atmospheric con-ditions, vehicle position, vehicle velocity,vehicle acceleration, aerodynamic drag,dynamic pressure, and timing of discreteevents are used to evaluate vehicle per-formance during flight. Solid and liquidengine thrust, specific impulse, flow rates,pressures, temperatures, stage energy per-formance, system performance margins,mixture ratio, and propellant margin pa-rameters are analyzed and compared topredictions.

Similarly, postflight analyses determinewhether all components performed as ex-pected. Measurements and data are com-pared with predictions and historical val-ues, and deviations are logged, analyzed,and resolved.

Additional postflight analyses includereview of radar, film, and video images col-lected during ignition, liftoff, and flight to

Cum

ulat

ive

failu

re r

ate

(per

cent

)

Government programengineering

Commercial program engineering

Commercial program workmanshipGovernment programworkmanship

1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001Calendar year

60

50

40

30

20

10

0

as of 2001 – 12 – 31

Government program engineering

Government program workmanship

Commercial program engineering

Commercial program workmanship

5 / 174 = 2.87%

1 / 174 = 0.57%

13 / 89 = 14.61%

1 / 89 = 1.12%

Cumulative failure rateType

Contribution of engineering errors to launch failures is relatively low ongovernment programs. During the last decade, the rate of failures

attributable to engineering errors on goverment programs was less than3 percent, compared with nearly 15 percent for commercial programs.

determine flight behavior (particularly dur-ing staging events) to identify any anom-alous conditions or sources of debris.

ConclusionAerospace’s end-to-end system review is aroutine but critical part of every SMClaunch. The impartial and independentlaunch verification provides assurance thatall known technical issues have been re-solved and that residual launch risks havebeen identified and assessed. When Aero-space signs off on its launch-readiness ver-ification, SMC can proceed with strongconfidence in ultimate mission success.

Further ReadingR. Johnson, “Independent Launch ReadinessVerification on the EELV Program,” Conferenceon Quality in the Space and Defense Industries,Proceedings (March 2002).

S. R. Strom, “A Perfect Start to the Operation:The Aerospace Corporation and Project Mer-cury,” Crosslink, Vol. 2, No. 2 (Summer 2001).

E. J. Tomei, I-S. Chang, J. Gazur, S. Guarro, A.Joslin, “ELV Launch Risk Assessment,” 3rd An-nual Government/Industry Mission AssuranceForum, Proceedings (September 2002).

C. L. Whitehair, M. G. Wolfe, and W. A. Kisko,“Space System Risk Management—The Aero-space Corporation Mission Readiness and Veri-fication Process,” 44th Congress of the Interna-tional Astronautical Federation Congress(October 1993).

C. L. Whitehair and M. G. Wolfe, “Space Sys-tem Risk Management: Launch Assurance,” 8thInternational Generali Conference on Commer-cial and Industrial Activities in Space (March1995).


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J. Ly, “Robust Multiloop Gain and Phase MarginCalculation Using mu Analysis and Spacecraft

Application,” AIAA/AAS Astrodynamics Spe-cialist Conference and Exhibit (Monterey, CA,Aug. 5–8, 2002). AIAA Paper 2002-5001.

D. K. Lynch, R. J. Rudy, R. W. Russell, C. J. Rice,S. M. Mazuk, C. C. Venturini, R. C. Puetter,M. L. Sitko, and R. Cutri, “Infrared Spectro-scopy of V4334 Sgr (Sakurai’s Object),” As-trophysics and Space Science, Vol. 279, No.1–2, pp. 57–64 (2002).

J. E. Mazur, G.M. Mason, and R.A. Mewaldt,“Charge States of Energetic Particles fromCorotating Interaction Regions as Constraintson Their Source,” Astrophysics Journal, Vol.566, No. 1, Pt. 1, pp. 555–561 (Feb. 10, 2002).

M. A. McMahan and R. Koga, “Radiation EffectsTesting at the 88-Inch Cyclotron at LBNL,”AIP Conference Proceedings, Vol. 610, No. 1,pp. 290–294 (Apr. 2, 2002).

G. Meholic, “Another Approach to the Cause ofInertia,” 38th AIAA/ASME/SAE/ASEE JointPropulsion Conference & Exhibit (Indianapo-lis, IN, July 7–10, 2002). AIAA Paper 2002-4096.

T. C. Meyers, P. T. Lin, B. A. Lucas, and R. C.Maynard, “Some Flight Termination Require-ment Rewrite Risk Considerations,” INCOSELos Angeles Mini-Conference (Long Beach,CA, June 8, 2002).

T. Nguyen, H. Nguyen, H. Tran, L. Jocic, and B.Lewis, “Survey on Diversity and CombiningTechniques,” 20th AIAA International Com-munication Satellite Systems Conference andExhibit (Montreal, Canada, May 12–15,2002). AIAA Paper 2002-1858.

T. Nguyen, H. Nguyen, H. Tran, J. Yoh, and B.Lewis, “Diversity and Combining Techniquesfor 2G and 3G PCS Systems,” 20th AIAA In-ternational Communication Satellite SystemsConference and Exhibit (Montreal, Canada,May 12–15, 2002). AIAA Paper 2002-1859.

T. W. Nuteson, J. S. Clark IV, D. S. Haque, and G.S. Mitchell, “Digital Beamforming and Cali-bration for Smart Antennas Using Real-TimeFPGA Processing,” 2002 IEEE MTT-S Inter-national Microwave Symposium Digest, Vol. 1(Seattle, WA, June 2–7, 2002), pp. 307–310.

T. W. Nuteson, G. S. Mitchell, R. F. Smith, D. S.Haque, J. S. Clark IV, M. W. Tompkins, andJ. E. Stocker, “Real-Time Implementation ofSmart Antenna Techniques,” 12th VirginiaTech/MPRG Symposium on Wireless PersonalCommunications (Blacksburg, VA, June 5–7,2002), pp. 51–60.

D. L. Oltrogge, “Satellite Threat Monitoring forCommunications Satellite Operators,” 20thAIAA International Communication SatelliteSystems Conference and Exhibit (Montreal,Canada, May 12–15, 2002). AIAA Paper2002-2020.

D. L. Oltrogge, R. G. Gist, and S. Alfano, “Satel-lite Mission Operations ImprovementsThrough Covariance-Based Methods,” SatMax2002: Satellite Performance Workshop (Ar-lington, VA, Apr. 22, 2002). AIAA Paper2002-1814.


Bookmarks Continued

A. Or, R. Wong, R. Atmadja, and J. Ly, “Perfor-mance Evaluation of a Precision Pointing Pay-load,” AIAA/AAS Astrodynamics SpecialistConference and Exhibit (Monterey, CA, Aug.5–8, 2002). AIAA Paper 2002-5000.

R. Patera, “Satellite Collision Probability for Non-Linear Relative Motion,” AIAA/AAS Astro-dynamics Specialist Conference and Exhibit(Monterey, CA, Aug. 5–8, 2002). AIAA Paper2002-4632.

R. Patera, “Space Vehicle Fly-By GuidanceMethod,” AIAA/AAS Astrodynamics SpecialistConference and Exhibit (Monterey, CA, Aug.5–8, 2002). AIAA Paper 2002-4813.

R. P. Patera, “The Probability of a Laser Beam Il-luminating a Space Object,” AAS/AIAA SpaceFlight Mechanics Meeting (San Antonio, TX,Jan. 27–30, 2002). AAS Paper 02-174.

R. P. Patera, “Quick Method to Determine Long-Term Orbital Collision Risk,” SatMax 2002:Satellite Performance Workshop (Arlington,VA, Apr. 22, 2002). AIAA Paper 2002-1809.

E. L. Petersen and M. W. Crofton, “Ignition andOxidation of Dilute Silane-Oxidizer MixturesBehind Reflected Shock Waves,” 38th AIAA/ASME/SAE/ASEE Joint Propulsion Confer-ence and Exhibit (Indianapolis, IN, July 7–10,2002). AIAA Paper 2002-3875.

G. Peterson, “Maneuver Optimization for Colli-sion Probability Reduction of Near-CircularOrbit Conjunctions,” AIAA/AAS Astrodynam-ics Specialist Conference and Exhibit (Mon-terey, CA, Aug. 5–8, 2002). AIAA Paper2002-4630.

G. E. Peterson, “Analytic Solution to COLA Ma-neuver Optimization for Near Circular Orbits,”AAS/AIAA Space Flight Mechanics Meeting(San Antonio, TX, Jan. 27–30, 2002). AASPaper 02-116.

S. Raghavan and J. Holmes, “Frequency BandSharing between NRZ and Split SpectrumSignals-Analysis and Simulation Results,”20th AIAA International CommunicationSatellite Systems Conference and Exhibit(Montreal, Canada, May 12–15, 2002). AIAAPaper 2002-2052.

P. R. Rousseau and P. Pathak, “A Time DomainUniform Geometrical Theory of Slope Dif-fraction for a Curved Wedge,” Turkish Journalof Electrical Engineering and Computer Sci-ences, Elektrik, Vol. 10, No. 2, pp. 385–398(2002).

R. J. Rudy, C. C. Venturini, D. K. Lynch, S. M.Mazuk, and R. C. Puetter, “Near-InfraredEmission Lines of V723 Cassiopeiae (NovaCassiopeiae 1995),” Astrophysics Journal, Vol.573, pp. 794–802 (July 10, 2002).

S. C. Ruth, “Risk Roadmaps—A Bridge Betweena Discipline and SE,” INCOSE Los AngelesMini-Conference (Long Beach, CA, June 8,2002).

R. S. Selesnick, “Cosmic Ray Access to Jupiter’sMagnetosphere,” Geophysical Research Let-ters, Vol. 29, No. 9, p. 12-1-4 (May 1, 2002).

M. R. Shane and R. D. Wesel, “Reduced Com-plexity Iterative Demodulation and Decodingof Serial Concatenated Continuous PhaseModulation,” 2002 IEEE International Con-ference on Communications Proceedings, Vol.3 (New York, NY, Apr. 28–May 2, 2002), pp.1672–1676.

C. P. Silva, A. A. Moulthrop, and M. S. Muha,“Polyspectral Techniques for Nonlinear Sys-tem Modeling and Distortion Compensation,”Third IEEE International Vacuum ElectronicsConference (Monterey, CA, Apr. 23–25,2002), pp. 314–315.

E. Simburger, J. Matsumoto, J. Lin, D. E. Freder-ica, S. Rawal, T. Peterson, and T. Kerslake,“Development of a Multifunctional InflatableStructure for the Power Sphere Concept,” 43rdAIAA/ASME/ASCE/AHS/ASC Structures,Structural Dynamics, and Materials Confer-ence (Denver, CO, Apr. 22–25, 2002). AIAAPaper 2002-1707.

T. R. Simpson, D. F. Hall, and G. K. Ternet, “Ex-traction of Properties of Condensed OutgassedSpecies by Thermogravimetric Analysis,” Op-tical System Contamination: Effects, Measure-ments and Control VII (Seattle, WA, July10–11, 2002), SPIE, Vol. 4774, pp. 150–159.

J. Siplon, J. Ewell, and T. Gibson, “ESR Concernsin Tantalum Chip Capacitors Exposed to Non-Oxygen-Containing Environments,” Micro-electronics Reliability, Vol. 42, No. 6, pp.829–834 (June 2002).

D. M. Speckman, T. L. Jennings, S. LaLu-mondiere, C. M. Klimcak, S. C. Moss, G. L.Loper, and S. M. Beck, “Biodetection UsingFluorescent Quantum Dots,” Technologies,Systems, and Architectures for TransnationalDefense (Orlando, FL, Apr. 3–4, 2002), SPIE,Vol. 4745, pp. 136–143.

D. M. Speckman, T. L. Jennings, S. D. LaLu-mondiere, and S. C. Moss, “Quenching Phe-nomena in Water-Soluble CdSe/ZnS QuantumDots,” Nanoparticulate Materials Symposium(Boston, MA, Nov. 26–29, 2001), MaterialsResearch Society Symposium ProceedingsVol. 704, pp. 269–274.

S. R. Strom, “Reaching for the Stars,” Cite: TheArchitecture and Design Review of Houston,No. 55, p. 34 (Fall 2002).

A. Sullins, R. Rogers, J. Ly, and C. Dunbar, “Al-ternate Beam Control Using Bragg Cell Dif-fraction,” AIAA Guidance, Navigation, andControl Conference and Exhibit (Monterey,CA, Aug. 5–8, 2002). AIAA Paper 2002-4999.

L. H. Thaller, “Dealing With Capacity Loss Mech-anisms in Nickel-Hydrogen Cells and Batter-ies,” Proceedings of the Sixth European SpacePower Conference (ESPC), (Porto, Portugal,May 6–10, 2002), pp. 553–560.

C. Wang, M. Shane, and T. Nguyen, “Radio Fre-quency Interference From Ground Radars to aGeostationary Satellite,” 20th AIAA Interna-tional Communication Satellite Systems Con-ference and Exhibit (Montreal, Canada, May12–15, 2002). AIAA Paper 2002-1948.

C. C. Wang and D. J. Sklar, “Performance of aTurbo Coded System With DPSK ModulationUsing Enhanced Decoding Metrics andMatched Channel Side Information,” 2002IEEE International Conference on Communi-cations Proceedings, Vol. 2 (Apr. 28–May 2,2002, New York, NY), pp. 773–777.

H. Wang and W. F. Buell, “Development of aMOT-Based Continuous Cold Cs-BeamAtomic Clock,” OSA Trends in Optics andPhotonics (TOPS), Vol. 74: Quantum Elec-tronics & Laser Science, pp. 93–94.

B. H. Weiller, L. Ceriotti, T. Shibata, D. Rein,M. A. Roberts, J. Lichtenberg, B. German, N.F. de Rooij, and E. Verpoorte, “Analysis ofLipoproteins by Capillary Zone Electrophore-sis in Microfluidic Devices: Assay Develop-ment and Surface Roughness Measurements,”Analytical Chemistry, Vol. 74, No. 7, pp.1702–1711 (2002).

K. Zondervan and D. Beck, “ApproximateClosed-Form Expression for the Probability ofBurst of a Pressurized Metal Cylinder Irradi-ated by a High-Energy Laser,” 33rd Plasmady-namics and Lasers Conference (Maui, HI,May 20–23, 2002). AIAA Paper 2002-2220.

Patents H. G. Campbell, R. E. Hovden, G. W. Law, “Janus

Reusable Spacecraft System,” U.S. Patent No.6,446,905, Sep. 2002.A spacecraft system having two substantiallysimilar reusable vehicles, one of which servesas a booster and the other as an orbiter, reducesthe cost and complexity of reusable launchsystems. The vehicles have identical flight-control and propulsion systems and identicalpayload bays for receiving mission-specificpayloads—for example, a propellant tank forthe booster and crew cabin for the orbiter.Each vehicle can be tailored to suit its flightfunction through the addition of standardizedcomponents; for instance, thermal protectionmight be added to the orbiter, but not to thebooster. The use of an identical booster andorbiter reduces overall costs because only onestage of the multistage launch vehicle need bedeveloped. The doubled production run re-duces manufacturing cost through greatereconomy of scale. Launch operations are sim-plified because only one type of stage needs tobe checked and refurbished after landing.

S. H. Choi, M. L. Leung, G. W. Stupian, N.Presser, “Electron Beam Lithography MethodForming Nanocrystal Shadowmasks andNanometer Etch Masks,” U.S. Patent No.6,440,637, Aug. 2002.Precise, nanometer-scale shadow masks orphotoresists for use during electron-beamlithography can be created from nanocrystals.The Langmuir-Blodgett process is used toform high-aspect-ratio lamellae or wire pat-terns of silver nanocrystals on the surface ofwater. The patterns are transferred onto resist-coated substrates as a Langmuir-Schaeffer film for producing the shadow mask. Thenanostructure patterns are transferred to the


photoresist by spatially selective electron-beam exposure. The nanocrystal structureshave a predetermined pattern for selectivelyblocking the electron beam. The process en-ables the creation of ultrafine nanometer-sizedpatterned structures for use in the manufactureof submicron-sized devices such as semicon-ductors and microelectromechanical systems.The combined use of low-energy electron-beam exposure and self-assembled nanocrys-tal shadow masks provide a low-costfabrication technique for forming nanometer-scale semiconductors.

J. K. Coulter and C. F. Klein, “Covert SurveillanceSystem for Tracking Light Sensitive TaggedMoving Vehicles,” U.S. Patent 6,465,787, Oct.2002.A covert tracking system uses a near-infraredbeam to illuminate a tag concealed on a vehi-cle to produce an image that can be monitoredby a near-infrared sensitive camera. Thistracking method employs an optical quarter-waveplate attached to an automobile licenseplate as the hidden tag and alternating pulsesof differently polarized light to enhance detec-tion of the tag. Using commercial off-the-shelf equipment, this surveillance systemoffers an inexpensive method for law enforce-ment personnel to track suspect vehicles andcargo shipments moving through traffic.

P. A. Dafesh, “Coherent Adaptive SubcarrierModulation Method,” U.S. Patent No.6,430,213, Aug. 2002.To help overcome the problem of limited spec-trum allocation for radio-frequency communi-cations, this signal modulation methodprovides efficient frequency reuse within exist-ing bandwidths. The generalized quadrature-product subcarrier modulation system enablesthe transmission of a quadrature multiplexedcarrier modulation with one or more subcarriersignals in the same constant-envelope wave-form. The process is suitable for efficient sine-wave and square-wave subcarrier modulations,including quadrature phase shift keying andminimum shift keying. Both direct and spread-spectrum quadrature multiplexed communica-tion systems are appropriate. The quadraturesubcarrier modulation enables the addition ofnew signals to the in-phase and quadrature-phase signals with spectral isolation whilemaintaining a constant amplitude waveform.

R. B. Dybdal and P. R. Rousseau, “Method to Re-solve Interferometric Ambiguities,” U.S.Patent No. 6,421,008, July 2002.This technique improves the performance ofinterferometric antennas that measure the di-rection from which radio signals are received.The method resolves interferometric ambigui-ties for wide-field-of-view systems that re-quire high angular accuracy and operationover wide bandwidths. In such designs, the in-dividual interferometric elements are rela-tively small. According to this new approach,multiple antenna elements within the overallbaseline provide a means by which to resolve

the interferometric ambiguities that resultbecause phase can be measured only over onecycle and the modulus cannot be determined.The antenna element spacings are configuredto allow high probability of ambiguity resolu-tion over a wide bandwidth. Additionally,radio-frequency combining techniques pro-vide synthetic baseline values for further am-biguity resolution. This approach provides thesystem designer with a means of minimizingthe number of interferometric elements—andhence cost and complexity—while having theassurance of correctly resolving the phase am-biguities with high probability.

O. Esquivel, “Contrast Imaging Method for In-specting Specular Surface Devices,” U.S.Patent No. 6,433,867, Aug. 2002.Suitable for examining large arrays of solarcells, this inspection technique allows forhigh-speed optical inspection of specular orhighly reflective surfaces. A contrasting pat-terned image is projected onto the specularsurface, which reflects it at an angle to a cam-era that scans and records it. Defects and flawsin the specular surface cause distortion of thereflected pattern, which are relatively easy todiscern. A video camera can be used to capturedetailed surface imagery of individual devices.The data can be compared with previous scansto determine, for example, whether surfacecracks have grown beyond acceptable levels.The system can be installed at a launch site toprovide rapid remote inspections.

J. K. Holmes, G. L. Lui, C.-S. Tsang, “Method ofDetermining the Carrier Reference Phase ofCoherent Demodulation of Frequency HoppedContinuous Phase Modulated Signals WithSynch Words Arbitrarily Located Within theHop,” U.S. Patent No. 6,449,304, Sep. 2002.This patent relates to carrier-phase determina-tion in frequency-hopped radio-frequencycommunication systems using Gaussian mini-mum shift keying, a form of continuous phasemodulation. Unambiguous carrier-phase esti-mation is enabled through the use of zeroingchannel bits and channel guard bits. The trans-mitter inserts these bits just prior to a knownsynch word during transmission of each fre-quency hop (the synch words are positionedarbitrarily within each hop). The inserted bitsforce the cumulative data phase to zero. Thereceiver detects these inserted bits and thuscan determine the carrier phase. Once the car-rier phase is known, the second data portion ofthe frequency hop can be demodulated, andduring a second demodulation pass, the firstdata portion can be demodulated.

G. L. Lui and K. Tsai, “Method and ProcessingSystem for Estimating Likelihood Ratios forInput Symbol Values,” U.S. Patent No.6,476,739, Nov. 2002.This invention pertains to the field of commu-nications, and more specifically to the Viterbialgorithms that are commonly used to demod-ulate received radio signals. It describes amethod and processing system for estimating

the likelihood ratios for input symbols and de-termining a soft-decision metric for each one.The process entails: computing trellis-branchmetrics based on a received sample sequence;updating initial-state metrics with a Viterbi al-gorithm; constraining trellises such that onlystate transitions caused by an input value asso-ciated with a particular trellis are allowed; ex-ecuting the Viterbi algorithm on theconstrained trellises for a finite number ofsteps; and computing likelihood ratios by tak-ing a difference of a maximum-state metric foreach trellis with a maximum-state metric of areference trellis.

D. C. Mayer, J. V. Osborn, S. W. Janson, P. D.Fuqua, “Addressable Diode Isolated Thin FilmArray,” U.S. Patent No. 6,437,640, Aug. 2002.Systems that employ arrays of cell elements—such as heating, pyrotechnic, thermionic, orfield-emitter elements—generally need to se-lectively address and activate them. Electri-cally addressable arrays of elements typicallyrequire extensive connections that necessitatecomplicated routing during semiconductorprocessing. This new approach offers a sim-pler alternative: An address element—includ-ing a polysilicon resistor, which functions as aheating element, and a blocking diode, whichprevents current from reaching unaddressedelements—is selectively addressed using rowand column address lines in a thin-film struc-ture having a minimum of address lines andlayers. The resistor heater element is wellsuited for igniting an individual fuel cell in athin-film microthruster array. The isolatingdiode allows for individual addressing ofmicron-sized pyrotechnic elements, cells, orother microelectromechanical devices. The ad-dressing method also enables selective inter-rogation of individual pyrotechnic cells todetermine whether or not they have beenignited.

D. C. Mayer, J. V. Osborn, S. W. Janson, P. D.Fuqua, “Addressable Diode Isolated Thin FilmCell Array,” U.S. Patent No. 6,483,368, Nov.2002.This patent describes a method of addressingindividual cells in an array. An address ele-ment—including a polysilicon resistor, whichfunctions as a heating element, and a blockingdiode, which prevents current from reachingunaddressed elements—is selectively ad-dressed using row and column address lines ina thin-film structure having a minimum of ad-dress lines and layers. The resistor heater ele-ment is well suited for igniting individual fuelcells in a thin-film microthruster array.

D. C. Mayer, J. V. Osborn, S. W. Janson, P. D.Fuqua, “Diode Isolated Thin Film Fuel CellArray Addressing Method,” U.S. Patent No.6,403,403, June 2002.This method of addressing individual cells inan array can be used in the design of a largearray of microthruster cells, each containingheat-sensitive combustible propellant, that canbe individually addressed and ignited without


Bookmarks Continued

damaging neighboring cells. The method ad-dresses and interrogates specific cells havingat least one resistor (which functions as a heat-ing element) and one blocking diode (whichprevents current from reaching unaddressedelements). The resistor is connected to a pri-mary addressing line and the diode is con-nected to a secondary addressing line. Thecells are selectively addressed using these rowand column address lines. A thin-film structurecan be thus created with a minimum of addresslines and a minimum of polysilicon layers.

T. M. Nguyen, J. K. Holmes, S. H. Raghavan,“Digital Timing Recovery Loop for GMSKDemodulators,” U.S. Patent No. 6,411,661,June 2002.Gaussian minimum shift keying (GMSK) is aform of continuous-phase modulation exhibit-ing compact spectral occupancy and a constantenvelope, which makes it compatible withnonlinear power amplifiers. This patent coversan improved GMSK timing recovery loop,which is used in a GMSK receiver to providethe bit-synchronization signal needed to re-construct a data sequence. The improved tim-ing recovery loop operates at baseband andreduces the bit-timing synchronization jitter,thereby lowering bit-error rates. The improve-ment lies in the combination of a hard limiterand a digital transition-tracking loop, whichrenders the synchronization performance in-sensitive to low bit-signal-to-noise ratios.

T. M. Nguyen, J. Yoh, A. S. Parker, D. M. John-son, “High Power Amplifier LinearizationMethod Using Extended Saleh Model Predis-tortion,” U.S. Patent No. 6,429,740, Aug.2002.Developed to improve the accuracy of digitalcommunication systems, this predistortionmethod serves to linearize the output of non-linear high-power amplifiers, which inherentlysuffer from amplitude and phase distortionwhen converting input signals to output sig-nals. The method can employ either an ex-tended Saleh model or a modified linear-logmodel. Either can be implemented using an ar-chitecture having real-to-complex conversionprior to predistortion and complex-to-real con-version after predistortion. A complex base-band linearizer provides predistortion atbaseband for reducing spectral regrowth andimproving bit-error performance. The predis-tortion effects are matched to the amplifier dis-tortions to cancel them out. The extendedSaleh model provides a general approachusing selected coefficients matched to distor-tion effects of a particular amplifier.

J. V. Osborn, “RF MEMS Switch,” U.S. PatentNo. 6,426,687, July 2002.A radio-frequency switch is manufacturedfrom a microelectromechanical systems(MEMS) substrate and a radio-frequency sub-strate, which are processed independently andthen bonded together. The switch is producedby encapsulating a flexing diaphragm that sup-ports a switch electrode, which is used with

electrostatic flexing potentials to move elec-trodes of the MEMS substrate up and downover a radio-frequency transmission line of theradio-frequency substrate. The result is an en-capsulated radio-frequency MEMS switchsuitable for direct coupling, ac coupling, anddirect modulation of radio-frequency signals.Resistant to external contamination, the switchprovides a reliable, minimally distorting radio-frequency transmission line for use in high-speed signal switching in advancedcommunication systems.

J. P. Penn, “High Concentration SpectrumSplitting Solar Collector,” U.S. Patent No.6,469,241, Oct. 2002.This solar collector employs a two-tiered ap-proach to achieve greater efficiency than pre-vious designs. The collector uses traditionalreflective or refractive optics to concentratecollected sunlight along a primary axis while aspectrum splitter sends sunlight along a sec-ond axis. The first axis can use traditionalFresnel lenses, curved prismatic Fresnel-typelenses, or mirrors. The spectrum-splitting axiscan be perpendicular to the first axis of con-centration. This solar concentrator and energyconverter provides high concentration ratiosand conversion efficiency using an array ofhorizontally disposed bandgap-optimized pho-tovoltaic cells.

E. J. Simburger, M. J. Meshishnek, D. G. Gilmore,D. A. Smith, M. H. Abraham, F. R. Jeffrey, P.A. Gierow, “Flexible Thin Film Solar Cell,”U.S. Patent No. 6,410,362, June 2002.A flexible space-qualified thin-film solar cellcan be produced with a thermally emissivelayer for heat rejection. A clear, thermallyemissive coating (such as clear polyimide) isdeposited directly upon a thin film to form aflexible thin-film solar cell. This cell can bedeposited on another thermally emissive coat-ing, which serves as a substrate during semi-conductor processing. The associatedinterconnects and power-processing electron-ics are integrated into this polymer substrate,forming a flexible printed circuit board. Theresulting flexible thin-film solar cell can be il-luminated on the top and eject heat from bothtop and bottom. The cell is suitable for form-ing a solar-cell array covering a curved surfacesuch as a PowerSphere nanosatellite.

K. Siri, “Fault Tolerant Maximum Power TrackingSolar Power System,” U.S. Patent No.6,433,522, Aug. 2002.This power-tracking system maximizes thepower deliverable from an energy source, suchas a solar array. It uses increasing, decreasing,and steady states controlled by a set-point sig-nal modulated by a dither signal. This allowsfor stabilized regular power tracking duringperiods of low demand and maximum powertracking during periods of high demand. Forsystems involving several power sources, mul-tiple sets of parallel-connected converters andmaximum-power trackers can be coupled inparallel using shared bus and control signalsfor fault-tolerant equalized power conversion.

When used with multiple solar arrays—whichcan have quite different characteristics—sometrackers can actively regulate maximum powerflows from arrays that have deficient powerwhile the remaining trackers are inactive. Thisis possible because the remaining solar arraysprovide sufficient power to allow dc-dc con-verters to regulate the load voltage.

G.-T. Tseng, J.-L. Yang, S. L. Johns, C. A. Wu,“GPS Patch Antenna Attitude ReferenceMethod,” U.S. Patent No. 6,452,543, Sep.2002.Determining the spin-axis attitude of a spin-ning space vehicle has been traditionally ac-complished using a combination of sun andEarth-horizon sensors. This approach offers analternative for vehicles orbiting below the GPSconstellation. An antenna pattern null is cre-ated to receive signals from at least three visi-ble GPS satellites, which function as pseudostars for reference. The new sensor system in-cludes a GPS receiver, a conventional sum anddifference hybrid, and two 1/4-wave-platepatch antennas.

G.-T. Tseng, J.-L. Yang, S. L. Johns, C. A. Wu,“GPS Patch Antenna Attitude Reference Sys-tem,” U.S. Patent No. 6,459,406, Oct. 2002.This patent describes a system for determiningthe spin-rate and spin-axis attitude of a spacevehicle in Earth orbit below the GPS constel-lation. A pair of 1/4-wave patch antennasforms an antenna pattern null for receiving sig-nals from at least three GPS satellites. Placedside by side on the space vehicle, the two an-tennas create an overlapping gain pattern withsum and null midway between them using aconventional 180-degree hybrid. The sum sig-nal is used for conventional GPS signal detec-tion and reception and for space-vehiclenavigation. The difference signal serves as atime reference for determining the spin rateand is also used to determine azimuth anglesfor the GPS satellites for computing the spin-axis attitude of the spacecraft.

R. J. Zaldivar, J. P. Nokes, G. F. Hawkins, “GlassTransition Temperature Measurement Sys-tem,” U.S. Patent No. 6,425,686, July 2002.This device can be used to identify the glass-transition temperature of a composite materialafter fabrication, thereby verifying that thematerial has cured completely. The system in-cludes a pointed probe that penetrates thesample. A heater raises the sample’s tempera-ture high enough to induce a phase changefrom solid to semisolid. A thermocouplemeasures the temperature while a motiontransducer measures the amount of probe pen-etration, which will increase sharply at theglass-transition temperature. A portable ver-sion can be used in the field to test the glass-transition properties of various compositematerials, including those used in buildingsand bridges. Used in conjunction with othernondestructive evaluation techniques, the sys-tem can check structures over the course ofmany years to verify their continued stability.


W. Paul Dunn, Principal Director, Launch Sys-tems Analysis Directorate, joined Aerospacein 1977 and has led the work on a number ofvehicle systems, including medium launchvehicles, the InertialUpper Stage, otherupper stages, propul-sive systems, vehiclesystems integration,and launch systemsanalysis. Among hismany honors is theDistinguished Gradu-ate Award from theUniversity of Texas atAustin in 1993, the highest award given bythe College of Engineering. Dunn earned aB.S. in civil engineering at UT, an M.S. incivil engineering at California State Univer-sity, Los Angeles, and an M.B.A. from Cali-fornia State University, Dominguez Hills([email protected]).

Art Falconer, Principal Director, TitanLaunch Verification, is responsible for en-suring Titan systems have been independ-ently verified as flightworthy and ready for

launch. He has morethan 37 years of ex-perience with launchvehicles, and for thepast 16, has supportedthe Titan program inthe areas of vehicledesign, qualification,test, satellite integra-tion, and launch oper-

ations. He has a B.S. in mechanical engineer-ing from the University of California,Berkeley, and has been with Aerospace for23 years ([email protected]).

Richard A. Hartunian joined Aerospace in1960, establishing the aerophysics depart-ment in the Aerodynamics and PropulsionResearch Laboratory. He served as generalmanager of the Reen-try Systems Divisionfrom 1968 to 1976,when he was namedvice president ofSpace Launch Opera-tions. During his nineyears in that position,he certified 130launches of Atlas,Delta, and Titan vehi-cles and was responsible for Aerospace sup-port of Air Force contributions to the spaceshuttle program. He received a B.S. inphysics from Rensselaer Polytechnic Insti-tute and a Ph.D. in aeronautical sciencesfrom Cornell University. He was elected afellow of AIAA in 1983 ([email protected]).

Ray F. Johnson, Vice President, Space LaunchOperations, is responsible for Aerospacesupport to Air Force launch programs, in-cluding Titan II, Titan IV, Delta II, Pegasus,Inertial Upper Stage, and the Evolved Ex-pendable Launch Vehicle, as well as the AirForce Space Test Program. He also has re-sponsibility for thecompany’s launch op-erations at CapeCanaveral and Van-denberg Air ForceBase and operationsin support of theSpace Test Programat Kirtland Air ForceBase. Johnson holds aB.S. in mechanicalengineering from the University of Califor-nia, Berkeley, and an M.B.A. from the Uni-versity of Chicago. He is a senior memberof AIAA and has been with Aerospace since1987 ([email protected]).

Jimmy F. Kephart, Project Engineer, SystemEngineering, Western Range Directorate,has performed many environmental assess-ments for launch programs at VandenbergAir Force Base, including the West Coast

Space Shuttle, TitanIV, and EELV. Amongthe numerous spacestudies and proposalshe has supported aresite selection for theTexas Space Commis-sion and evaluation ofKiritimati Island forthe Japanese J-II NewCentury. A major in

the Air Force before joining Aerospace in1991, Kephart worked on research and de-velopment for the Gemini program, theManned Orbital Laboratory, West CoastSpace Shuttle, and various satellites and bal-listics. He is a graduate of the Industrial Col-lege of the Armed Forces and holds an M.S.in aerospace engineering from the Air ForceInstitute of Technology ([email protected]).

E. J. (Joe) Tomei, Chief Engineer for SpaceLaunch, Space Launch Operations, is re-sponsible for horizontal engineering acrossall launch programs. Previously, he servedas chief engineer forthe EELV programand principal engineerfor plans and analysisfor Space Launch Op-erations. Tomei joinedAerospace in 1979 onthe West Coast SpaceShuttle program,serving as develop-ment and operationsdirector for Space Launch Complex 6 until1988. He provided testing and launch sup-port for the first two shuttle missions fromKennedy Space Center. Tomei has an M.S.in aerospace engineering from the Univer-sity of Southern California ([email protected]).

Joseph F. Wambolt, Principal Director, West-ern Range Directorate, manages Aerospaceactivities in support of DOD space-launchprograms at Vandenberg Air Force Base.

Since joining Aero-space in 1960, he hasheld many managerialpositions in launch-vehicle systems. Hisorganization receivedthe Aerospace Pro-gram RecognitionAward for the DeltaProgram in 1992 andfor the Atlas E/F Pro-

gram in 1995. He shared The AerospacePresident’s Award in 1990 for program man-agement, and in 2000 received the com-pany’s highest award, The AerospaceTrustees’ Distinguished AchievementAward, for his management and technicalleadership. Wambolt has a B.S. in chemicalengineering from Northeastern University,Boston, and an M.S. in business administra-tion from California State University,Dominguez Hills ([email protected]).

Contributors

The Crosslink editorial staff.From left to right:Steven R. Strom, Robert Wright,Gabriel Spera, Donna Born,Jon Jackoway


The Back Page Rocket genealogy

Aerobee

Viking

Navaho

Vanguard

Saturn I

Saturn V

Titan IIIC

Thor

Scout

Titan I

Minuteman I/II

Delta

Atlas A-H

V2

1945 1955 1965

Polaris

Bumper

Titan II

Jupiter

Centaur

Redstone

Juno I

Corporal

Minuteman IIIThis chart shows the lineage of major U.S.space launch vehicles. Many trace their

roots to the V-2, brought back from Germanyafter World War II. Previously, the United Stateshad been developing rockets, such as the Cor-poral, but none was as sophisticated as the V-2.

The postwar period saw the birth of theArmy’s Aerobee and Bumper (the first two-stage rocket) and the Navy’s Viking soundingrockets. Viking was chosen as the first stageand Aerobee as the second stage for the Navy’sVanguard rocket. Vanguard later lent compo-nents and systems to Thor and its successor,Delta, as well as the small Scout rocket and theAir Force’s Atlas. Scout was America’s firstsolid-fuel launch vehicle capable of putting asatellite into orbit; it took its first stage from theNavy’s Polaris missile and upper stages fromVanguard. Polaris technology would also findits way into Minuteman ICBMs. Minuteman

technology is now used to build small launchvehicles such as Pegasus and Minotaur.

Another early weapon program led to theNavaho cruise missile. Although the Navahoprogram did not last long, its legacy was signif-icant. The Navaho booster engine, adaptedfrom the V-2, was used in the development ofAtlas, Redstone, Jupiter, Thor, and Titan I.

Atlas D, the first operational ICBM, was de-ployed in 1959. These missiles were later re-furbished as space launch vehicles. Atlas gaveway to the Atlas II family, which gave rise toAtlas V, one of two boosters in the Evolved Ex-pendable Launch Vehicle (EELV) program.

The Thor ballistic missile program began in1954. Although its airframe design was new,some of Thor’s subsystems were borrowedfrom Atlas, including the guidance system andthe Navaho-based booster engine. The AirForce soon began adding upper stages to Thor,

creating Thor-Able, Thor-Able Star, Thor-Agena, and Thor-Delta—or simply Delta, as itcame to be known.

Delta was first launched in 1960 using a sec-ond stage borrowed from Vanguard. Solid-rocket motors, derived from Scout, were addeda few years later. Today, Delta IV is one of twoboosters in the EELV program.

In 1961, the Army’s Redstone rocket carriedthe first American into space. The Redstone,given two upper stages, became Jupiter C, laterrenamed Juno I; its liquid-propellant main-stageengine came from Navaho. A Jupiter C placedthe first U.S. satellite into orbit. Juno I and theJupiter ballistic missile combined to form JunoII. Redstone, Jupiter, and Juno led to the Saturnseries, culminating in the massive Saturn V.

Atlas V

Space shuttle

Titan IV

Delta II

Delta III

Pegasus XL

Peacekeeper

Minotaur

Delta IV

Atlas III

Taurus

20051985 1995

Athena I/II

Atlas I/II

The first Titan ICBM was deployed in 1962.Development of Titan II began the same year.Many variants of Titan III emerged, includingthe IIIC and 34D, whose solid motors werederived from Minuteman. The seven-segmentTitan IIIM, conceived but never built for thecanceled Manned Orbiting Laboratory, laterresurfaced as Titan IV.

Centaur was the first American high-energy,liquid-hydrogen/liquid-oxygen rocket. Until1974, Centaur was used exclusively with Atlas.It was later used with the Titan III and IVboosters and contributed to the Saturn series.

Propulsion system concepts and technologiesfrom Saturn V and Titan III were applied to thespace shuttle, whose main engines in turn con-tributed to the RS-68 engine used on Delta IV.

Editor in ChiefDonna J. Born

EditorRobert P. Wright

Guest EditorRay F. Johnson

Managing EditorGabriel Spera

Contributing EditorSteven R. Strom

Staff EditorJon Jackoway

Art DirectorThomas C. Hamilton

IllustratorJohn A. Hoyem

PhotographerEric Hamburg

Editorial BoardMalina Hills, ChairDavid A. Bearden

Donna J. BornLinda F. Brill

John E. ClarkDavid J. EvansIsaac GhozeilLinda F. Halle

David R. HickmanMichael R. Hilton

John P. HurrellWilliam C. KrenzMark W. MaierMark E. Miller

John W. MurdockMabel R. Oshiro

Fredric M. Pollack

Copyright 2003 The Aerospace Corporation. All rights reserved. Permission to copy orreprint is not required, but appropriate credit must be given to The Aerospace Corporation.

Crosslink (ISSN 1527-5264) is published by The Aerospace Corporation, an independent,nonprofit corporation dedicated to providing objective technical analyses and assessmentsfor military, civil, and commercial space programs. Founded in 1960, the corporation oper-ates a federally funded research and development center specializing in space systems archi-tecture, engineering, planning, analysis, and research, predominantly for programs managedby the Air Force Space and Missile Systems Center and the National Reconnaissance Office.

For more information about Aerospace, visit www.aero.org or write to Corporate Com-munications, P.O. Box 92957, M1-447, Los Angeles, CA 90009-2957.

For questions about Crosslink, send email to [email protected] or write to The Aero-space Press, P.O. Box 92957, Los Angeles, CA 90009-2957. Visit the Crosslink Web site atwww.aero.org/publications/crosslink.

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