COMSTAR D-2 Press Kit

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NASAs News 'National Aeronautics andSpace AdministrationWashington. D C 20546AC 202 755-8370

For Release IMMEDIATE

Press Kit Project COMSTAR D-2RELEASE NO: 76-127

ContentsGENERAL RELEASE ....................................... .1-2ATLAS/CENTAUR LAUNCH VEHICLE .......................... 3-5TYPICAL LAUNCH SEQUENCE FOR COMSTAR D-2 ................. 6NASA TEAM ............................................. 7-8


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NA\SA Newsational Aeronautics andSpace AdministrationWashington. DC 20546AC 202 755-8370

Fo r ReleaseBill O'DonnellHeadquarters, Washington, D.C. IMMEDIA2E(Phone: 202/755-3090)

RELEASE NO: 76-127

NASA TO LAUNCH SECOND COMSTAR FOR COMSAT GENERALCOMSTAR D-2, the second in a series of domestic

communications satellites of COMSAT General Corp., isscheduled for launch by NASA July 22 at Cape Canaveral, Fla.

The Atlas/Centaur vehicle and associated support activ-ities will be provided on a cost-reimbursable basis by NASAto COMSAT General, a subsidiary of Communications SatelliteCorp. (COMSAT).

The COMSTAR satellite has been leased by COMSATGeneral to American Telephone and Telegraph Co. (AT&T) aspart of its nationwide communications network. EachCOMSTAR has a capacity for more than 14,000 two-way highquality voice circuits.

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Three in-orbit COMSTARS are planned for the systemwhich will be capable of providing communications co the50 states and Puerto Rico. The first COMSTAR was launchedMay 13 and the third is scheduled for launch in 1978.A fourth will serve as a ground spare.

The COMSTAR satellites operate from geosynchronousorbits at 36,000 kilometers (22,300 miles) altitude.

Launch window July 22 opens at 6:04 and closes at7:13 p.m. EDT.

NASA's Lewis Research Center, Cleveland, Ohio, hasmanagement responsibility for the Atlas/Centaur developmentand operation. NASA's John F. Kennedy Space Center, Fla.,is responsible to Lewis Research Center for vehicle checkoutand launch.

(END OF GENERAL RELEASE. BACKGROUND INFORMATION FOLLOWS)


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ATLAS/CENTAUR LAUNCH VEHICLE

The Atlas/Centaur is NASA's standard launch vehicle forintermediate-weight payloads. It is used for the launch ofEarth-orbital, Earth-synchronous and interplanetary missions.Centaur was the nation's first high-energy, liquid-hydrogen/liquid-oxygen propelled rocket. Developed andlaunched under the direction of NASA's Lewis Research Center,it became operational in 1966 with the launch of Surveyor 1,the first U.S. spacecraft to soft-land on the Moon's surface.Since that time, both the Atlas booster and Centaursecond stage have undergone many improvements. At present,the vehicle combination can place 4,530 kilograms (10,000pounds) in low Earth orbit, 1,880 kg (4,150 lb.) in a syn-chronous transfer orbit and 900 kg (2,000 lb.) on an inter-planetary trajectory.The Atlas/Centaur, standing approximately 40.8 meters(134 feet) high, consists of an Atlas SLV-3D booster andCentaur D-lA second stage. The Atlas booster develops 1,920kilonewtons (431,3D0 lb.) of thrust at liftoff using two822,920-newton (185,000 lb.) thrust booster engines, one266,890-N (60,000 lb.) thrust sustainer engine and two ver-nier engines developing 2,890 N (650 lb.) thrust each. Thetwo RL-10 engines on Centaur produce a total of 133,450 N(30,000 lb.) thrust. Both the Atlas and the Centaur are3.048 m (10 ft.) in diameter.Until early 1974, Centaur was used exclusively in com-bination with the Atlas booster. Now it Ls also used witha Titan III booster to launch heavier payloads into Earthorbit and interplanetary trajectories.The Atlas and the Centaur vehicles have been updatedover the years. Thrust of the Atlas engines has been in-creased about 222,400 N (50,000 lb.) since its debut in thespace program in the early 1960s.The Centaur D-1A has an integrated electronic systemthat performs a major role in checking itself and othervehicle systems before launch and also maintains controlof major events after liftoff.

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The new Centaur electronics handles iiav gation and guidancetasks, controls pressurization and venting, ropellant man-agement, telemetry formats and transmission and initiatesvehicle events. Most operational needs can ne met bychanging the computer software.

The Centaur D-lAR also incorporates a redundant hydro-gen peroxide attitude control system that is tolerant of aperoxide "engine out" situation.

Typical Launch Vehicle Characteristics

Liftoff weight including spacecraft: 148,j'5 kg (326,400 lb.)Liftoff height: 40.8 m (134 ft.)Launch complex: 36-B

Atlas Booster Centaur StageWeight 130,469 kg 17,781 kg(with propellants) (287,630 lb.) (39,200 lb.)Height 21.3 m (70 ft.) 19.5 m (64 ft.with payloadfairing)Thrust 1,920 kn 133,450 N(431,300 lb.) (30,000 lb.)at sea level. in vacuum,Propellants Liquid oxygen Liquid oxygenand RP-1 and liquidhydrogenPropulsion MA-5 svstem two Two 66,723-N822,921-N (185,000 (15,000-lb.)

lb.) thrust booster thrust RL-10engines, one engines, 12266,893-N (60,00 small hydrogenlb.) thrust su6- peroxide thrusters.tainer engine, -wo2,891-N (650-1:.)thrust vernic-engines.

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Atlas Booster Centaur StageVelocity 8,877 kmph (5,517 33,339 kmph(Earth relative) mph) at booster (20,714 mph)

engine cutoff at spacecraft(BECO), 12,294 separation.kmph (8,076 mph)at sustainerengine cutoff(SECO).

Guidance Preprogrammed pro- Inertial guidance.file through BECO.Switch to inertialguidance for sus-tainer phase.

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NASA TEAM

NASA HeadquartersJohn F. Yardley Associate Administratorfo r Space Fl.ightJoseph B. Mahon Director of ExpendableLaunch Vehicle Programs

F. R. Schmidt Manager, Atlas/Centaur

Lewis Research CenterDr. Bruce T. Lundin DirectorDr. Seymour C. Himmel Associate Director for

Flight ProgramsAndrew J. Stofan Director of Launch VehiclesHenry 0. Slone Centaur Systems ManagerKenneth A. Adams COMSTAR I Mission Project

EngineerRichard A. Flage Launch Vehicle TestIntegrat ion EngineerRichard E. Orzechowski Launch Vehicle RangeIntegration Engineer

Kennedy Space Center

Lee R. Scherer DirectorMiles Ross Deputy DirectorDr. Walter J. Kapryan Director, Space Vehicles

OperationsGeorge F. Page Director, Expendable VehiclesJohn D. Gossett Manager, Centaur Operations

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Kennedy Space Center (cont'd)Creighton A. Terhune Engineering Manager,Centaur OperationsJ. M. HarringtOn Complex 36 OperationsManagerJames N. McKnight Project Engineer, COMSTARSpacecraft

COMSAT GeneralRobert D. Briskman Assistant Vice Presidentand Director of COMSTAR

Program

Jul.y 14, 1976

COMSTAR D-2 Press Kit

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