Venus Observations Flight Readiness Review Delta FRR (HST Program 12433) 19 January 2011.
Venus Observations Flight Readiness Review (HST Program 12433) 22 December 2010.
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Transcript of Venus Observations Flight Readiness Review (HST Program 12433) 22 December 2010.
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Venus ObservationsFlight Readiness Review
(HST Program 12433)
22 December 2010
2010/2011 Venus Observation
P. 222 Dec 2010
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1.0 Venus Observation Tony Roman
2.0 FSW, S/C H/W Changes and Implementation Brian Vreeland2.1 FSW and/or S/C H/W Functional Changes2.2 FSW Software Structure/Resource Changes2.3 Supporting Ground System Changes2.4 Supporting Documentation Changes2.5 Release Messages2.6 Unit and Build Level Testing/Results2.7 System Level Testing/Results
3.0 Engineering Test / Installation3.1 Overview and Initial Conditions Ben Teasdal3.2 Script Review Ben Teasdal3.3 Standalone Testing Mike Wenz /
Steve Arslanlian
3.4 Timeline Review Ben Teasdal3.5 MEGG Ben Teasdal
Agenda
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Agenda
4.0 Monitoring and System Impacts Wayne Burdick4.1 On-orbit Validation / Monitoring4.2 System Impacts4.3 Supporting Operations Changes 4.4 Supporting PRD Changes4.5 Training Module Changes
5.0 Constraints and Restrictions Review Wayne Burdick5.1 CARD
5.2 OLD
6.0 Contingency Planning Wayne Burdick6.1 Vehicle Contingencies6.2 Other Contingencies
7.0 Engineering Support Requirements Wayne Burdick7.1 Personnel7.2 Communications / Data7.3 CCS
8.0 Liens / Issues Wayne Burdick
9.0 Forward Plan Wayne Burdick
10.0 Actions Wayne Burdick
2010/2011 Venus Observation
P. 422 Dec 2010
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Engineering Team
STScI - Tony Roman, Merle Reinhart, Alan Welty, Charles ProffittOTA - Mike Wenz, Dennis Crain, Art BradleyDMS / I&C– Ben Teasdel and Jessica RegaladoFSW – Brian Vreeland, Norm Roy, Shirley Duhaney, Suzanne Benedict, Susan
Lien, Vicki van Duyl, Anthony Wells, Clive Caldwell, Linda MitchellPayload FSW - Dennis Garland PCS – Dave MurphyEPS – Stan KrolSI – Scott SwainThermal – Josh AbelSafing – Ed MoyOperations – Lynn Bassford, Joe CooperSystems Management – Wayne Burdick
2010/2011 Venus Observation
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Objectives & Overview
• Explain Venus observing strategy.• Review areas of special concern with Venus observations and explain how
these concerns are being addressed.• Determine if the implementation is correct and complete.
• Why is Venus Special ?• At its farthest, Venus gets to be about 47 degrees from the Sun.• HST is normally not permitted to point within 50 degrees of the Sun.
2010/2011 Venus Observation
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Venus Observing Program History
• In 1995, HST observed Venus with GHRS and WFPC2 (GO 4518 and GO 5783).
• In 1996, two GO Venus proposals (6607 and 6771) were approved by the TAC; and there was one GTO/WF2 program (6851) to observe Venus. All of these were cancelled by the STScI Director shortly after phase 2 submission.
• In 1997, there was a GTO/STIS program (7581) to observe Venus. Much implementation work was done, but the program was then withdrawn by the PI.
• In 2003, HST observed Venus with STIS (GO 8659).• NASA program 12433 is now planned for:
• December 27-28, 2010 (2010.361-362)• January 22, 2011• January 27, 2011
2010/2011 Venus Observation
P. 722 Dec 2010
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Goals & Strategies
• Scientific Goals• Coordinated observing with ESA’s Venus Express mission.• Map variations in SO2, SO, S2, and other UV absorbers.• Constrain models of Venus atmosphere and climate evolution
• Observing Strategy• Observe while Venus is near maximum elongation• Observe while HST is in Earth’s shadow
• A window of 9-14 minutes per orbit• Three visits of 2 orbits each.• Originally to have also been coordinated with Atkatsuki mission, but that
spacecraft failed to achieve Venus orbit
2010/2011 Venus Observation
P. 822 Dec 2010
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Target Visibility
GS Pair Acqat Venus+5D
Slew to Venus
Target Visibility
Shadow
GS Pair Acq at Venus+5D
Observing Strategy Details
• Initial GS Acq at Venus+5D• A pointing 5.5 degrees from Venus and 51.6 degrees from the Sun.• Minimizes slew distance to Venus• Precautionary measure to protect against large pointing error after slew
Observe Venus
Slew to Venus +5D
Single GS Acq at Venus
OBAD
Target Visibility
Slew to Venus
Shadow
GS Pair Acq at Venus+5D
Observe Venus
Slew to Venus +5D
Single GS Acq at Venus
OBAD
2010/2011 Venus Observation
P. 922 Dec 2010
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Target Visibility
GS Pair Acqat Venus+5D
Slew to Venus
Target Visibility
Shadow
GS Pair Acq at Venus+5D
Observing Strategy Details
• Single GS Acq at Venus• Saves about a minute versus pair acquisition
• Venus science observation• 153s exposure• STIS auto wave cal disabled
Observe Venus
Slew to Venus +5D
Single GS Acq at Venus
OBAD
Target Visibility
Slew to Venus
Shadow
GS Pair Acq at Venus+5D
Observe Venus
Slew to Venus +5D
Single GS Acq at Venus
OBAD
2010/2011 Venus Observation
P. 1022 Dec 2010
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Venus Appearance at Observation
• Apparent magnitude: -4.1 +/- 0.2• Surface brightness: +1.5 (average for 1 square arcsecond of illuminated
portion of disk)• Apparent diameter: 28.5 arcseconds• Phase angle: 97.3 degrees
2010/2011 Venus Observation
P. 1122 Dec 2010
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Vital Statistics
ObservationScience Exposure Time
Angle to Sun Limb (degrees)
Sunlit Time inside SAZ While Slewing Away from Venus Guide Star
January 1995 22-109s per orbit
46.3 2m 20s
January 2003 255s 46.0 2m 30s
Dec 28, 2010 orbit 1 153s 46.2 2m 14s (after GS time adjust)
S924000129 in FGS1on centerline
Dec 28, 2010 orbit 2 153s 46.2 3m 2s (after GS time adjust)
S924000129 in FGS1~50” from centerline
Jan 22, 2011 orbit 1 80s (153s requested)
46.1 2m 38s S8OF000650 in FGS1
Jan 22, 2011 orbit 2 80s (153s requested)
46.1 2m 36s S8OF000650 in FGS1
Jan 27, 2011 orbit 1 314s 45.7 2m 56s S8LA045471 in FGS2
Jan 27, 2011 orbit 2 20s 45.7 0m 0s S8L2047229 in FGS1
2010/2011 Venus Observation
P. 1222 Dec 2010
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Areas of Concern
• Guide star acquisition failure• Spacecraft or instrument problem shortly before scheduled observing time• FGS exposure to Venus• HST being exposed to sunlight while pointed within the Solar Avoidance Zone
(SAZ)• HST safing while pointed within the SAZ
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Guide Star Acquisition Failure
• Concern• If attitude error is greater than the search radius, the guide star acquisition could fail
resulting in the loss of the science.• Precautions
• The chances are minimized by the short 5 degree slew to Venus.• Too late to perform guide star acquisition test. Stars are in solar avoidance zone.• Science exposures will proceed even if GS acquisition fails.
• Special commanding specified to ignore “take data” flag.• AQEXPIRE timer adjusted via SMS edit.
• Detector is protected because HST is in shadow• CCD is utilized for observation
2010/2011 Venus Observation
P. 1422 Dec 2010
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Problem Shortly Before Observation
• Concern• An unrelated problem may threaten the Venus observing window.• In 1995, the Venus observation was originally lost due to an unrelated safing; but it
was quickly replanned and executed successfully.• The 2003 Venus observations were delayed from 2001 due to the failure of the
STIS side 1 electronics.
• Remedy• Second choice coordination opportunity with Venus Express on January 23, 2011
2010/2011 Venus Observation
P. 1522 Dec 2010
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FGS Exposure To Venus
• Concern• If the attitude error is large enough (> 300 arcseconds), an FGS could
possibly see Venus and cause potential bright light exposure to the FGS photo-multiplier tubes.
• Precautions• Choose a guide star that is as far as possible from Venus.• The chosen guide star is magnitude 12.4 and will be about 15.5 arcminutes
from Venus.• FGS PMT can tolerate and return to normal performance.
• Goodrich assessed PMT damage should a worst-case event occur resulting in an attempted acquisition of Venus with an FGS (ref: Goodrich Memo A16-ST-2254)
• Goodrich reports the short-term effect of the Venus acquisition would be the temporary incapacitation of the PMTs due to dark count elevation. While the exact value is not available for the given intensity, literature quotes range from several to 48 hours for recovery (for any target).
• Goodrich performed a relative assessment of the long-term effects of Coulomb draw (charge depletion) while attempting to acquire Venus with an FGS. While it is hard to determine exactly how the FGS would behave if it attempted to perform an acquisition on Venus, depending on how long it spends with Venus in the FOV, you could see a decrease in reliability from 1-3%.
2010/2011 Venus Observation
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HST FOV
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HST in the Sun
• Concern• While slewing away from Venus, HST will be exposed to sunlight and pointed
inside the SAZ for up to 3m 2s.• HST’s maximum previous exposure to sunlight while pointed inside the SAZ was
2m 30s (2003 observation).• Pointing inside the SAZ while HST is in sunlight can be tolerated for at least 15
minutes before the temperature of the paint inside the OTA would become a contamination issue. (EM-MOSES-1267 and EM-MOSES-1268)
• TCS has analyzed limits and has confirmed duration can be tolerated.
• Precautions• Guide star search radius was reduced in order to save 10-30 seconds of
acquisition time.
2010/2011 Venus Observation
P. 1822 Dec 2010
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HST Safing
• Concern• HST must not enter inertial hold safe mode while pointed within the SAZ.
• Precautions• Modifying the inertial hold safe mode response such that any condition that would
normally lead to inertial hold without closing the AD leads to software sun point safe mode instead.
• This was done in both prior HST observations of Venus.
2010/2011 Venus Observation
P. 1922 Dec 2010
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2010 Venus ObservationsGSACQ Adjustments
Mike Wenz for Merle Reinhart
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P. 2022 Dec 2010
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GSACQ Adjustments
• Idea is to compress the time allowed for the single-star GSACQs to minimize the time in sunlight within 50° of the sun and/or provide more science exposing time.
• Obvious places for a time compression are• Spiral Search time• Move back to the target attitude (GS Offset via #43 command)
• STIS will ignore the TDF via special commanding. Thus, need to ensure if the GSACQ fails, that we are back at the target attitude for the science exposure.
• This implies a reasonable setting of the AQEXPIRE timer in the SMS call to the GSACQ PLCP.
2010/2011 Venus Observation
P. 2122 Dec 2010
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GSACQ Time ReductionSpecifics – Dec Visit: Orbits 0 & 1
• Orbit #0• OBAD with Trackers 1 & 3
• Tracker 2 is explicitly avoided due to Capella (mag 0.08) being on the edge of the field and a fairly bright variable star (mag 1.81) being in the field
• Orbit #1• OBAD with Trackers 1 & 3 immediately prior to single-star gsacq• Assumed error after the OBAD at the start of the gsacq is 20”
• PCS indicates nominal post-OBAD error is 10-12”, but 20” is used to be conservative
• Time for spiral search = 32s (-40s)• At the target position, the guide star is <1” from the pickle centerline
• Time for 21” decenterline maneuver = 32s (-23s)• However, since we are telling STIS to ignore the TDF for these observations,
we want to set AQEXPIRE to prior to start of Track51 slew• Thus likely get data even if the gsacq fails• Time for AQEXPIRE to fire and complete is 35s
• 27s for maneuver + 8s for other overheads• Final GSACQ time = 344s + (-40s + -23s + 35s) = 316s• AQEXPIRE value = 316s – 35s – 3s = 278s
• The -3s is the AQEXPIRE timer isn’t enabled until 3s into the PLCP
2010/2011 Venus Observation
P. 2222 Dec 2010
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GSACQ Time ReductionSpecifics – Dec Visit: Orbit #2
• Orbit #2• OBAD with Trackers 1 & 3 immediately prior to single-star gsacq• Assumed error after the OBAD at the start of the gsacq is 20”
• Time for spiral search = 32s (-40s)• At the target position, the guide star is 52” from the pickle centerline
• Time for 72” decenterline maneuver = 49s (-6s)• However, since we are telling STIS to ignore the TDF for these observations, we want to set
AQEXPIRE to prior to start of Track51 slew• Time for AQEXPIRE to fire and complete is 52s
• 44s for maneuver + 8s for other overheads
• Final GSACQ time = 344s + (-40s + -6s + 52s) = 350s• AQEXPIRE value = 350s – 52s – 3s = 295s
• The AQEXPIRE changes are done as an SMS Edit.• If edit were to not occur, the only effect would be if the GSACQ failed, the spacecraft would
not be maneuvered back to the target position prior to the initiation of the Track51 for the exposure.
2010/2011 Venus Observation
P. 2322 Dec 2010
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2.0 FSW, S/C H/W Changes and Implementation
FSW – Brian Vreeland
2010/2011 Venus Observation
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2.0 FSW, S/C H/W Changes and Implementation
2.1 FSW and/or S/C H/W Functional Changes• Venus Observation SPC Macros (DCR 1552)
• Load File – QVENUS0_0.TAB • Contains 2 Macros
• Activation Macro at SPC Address 19824 (Jump Table Addr 1)• Perform BMIC management for the modified Tables• Modify the Sunpoint Sun Cosine Limit from 46 to 42 degrees• Modify six Safe Test Responses from Inertial Hold to Software Sunpoint (w/o
Load Shed)• SBREHE - High Mode Body Rate Error• SSPCLEXE – SPC List Exhaust• SBMICE - BMIC• SEMBOPE - Earth-Moon Protection• SMHGATCT - HGA Torque Limit• SNELEAKE - Neon Leak tests
• Other Inertial Hold Test Responses Close AD in addition to IH and are not changed in macro
• SPSEAPSE - PSEA Power Supply Failure• SSUNAPRE - Sun Aperture • SSBOPE - Sun Bright Object Protection• Thermally safe if Aperture door is closed and HST is at 46 degress
2010/2011 Venus Observation
P. 2522 Dec 2010
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2.0 FSW, S/C H/W Changes and Implementation
2.1 FSW and/or S/C H/W Functional Changes (cont…)
• Restoration Macro at SPC Address 19825 (Jump Table Addr 2)• Perform BMIC management for the modified Tables• Restore the Sunpoint Sun Cosine Limit from 42 to 46 degrees• Restores six Safe Test Responses from Software Sunpoint to Inertial Hold
• Installation and Usage Procedure “IP-219_Venus_Observation_Macros.docx”• 3 Sections
• Load, Dump and Compare QVENUS0_0.TAB, to verify the load• Execute the Activation Macro as required• Execute Restoration Macro as required
2010/2011 Venus Observation
P. 2622 Dec 2010
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2.0 FSW, S/C H/W Changes and Implementation
2.2 FSW Structure/Resource Changes – None2.3 Supporting Ground System Changes - None2.4 Supporting Documentation Changes - None2.5 Release Messages
• SSM212• IP-219_Venus_Observation_Macros.docx• PNM_20103473812.TXT
2.6 Unit and Build Level Testing/Results• None Needed
2010/2011 Venus Observation
P. 2722 Dec 2010
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2.0 FSW, S/C H/W Changes and Implementation
2.7 System Level Testing/Results • Software Simulation Environment
• 8 FVS tests run to verify proper configuration after macro execution• VENOBS1 – Venus Observation Test 1 - Nominal Case• VENOBS2 – Venus Observation Test 2 - SPC List Exhaustion • VENOBS3 – Venus Observation Test 3 - BMIC Failure• VENOBS4 – Venus Observation Test 4 - High Body Rate Error• VENOBS5 – Venus Observation Test 5 - Earth/Moon Protection Error• VENOBS6 – Venus Observation Test 6 - HGA Torque Limit• VENOBS7 – Venus Observation Test 7 - Sun Cosine Limit• VENOBS8 – Venus Observation Test 8 - Neon Leak Case
• Verified that Software Sunpoint commanded versus Inertial Hold• Hardware Test Environment
• Lab Configuration• CCS 7.1.1.0.4 / PRD O07300R1S • PCSSIM 51A• On-Orbit Patches Installed• Gyro 3-4-5
• Installation Procedure Verification using VSSNOR and IP• Completed in LMB
2010/2011 Venus Observation
P. 2822 Dec 2010
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2.0 FSW, S/C H/W Changes and Implementation
2.8 H/W Interfaces Impact & Verification Matrix• N/A
2.9 CPM2 & 3 Update Recommendation• N/A
2010/2011 Venus Observation
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3.0 Engineering Test / Installation
• 3.1 Overview and Initial Conditions• SSM486 Flight Software Version 3.4 or higher and currently executing in VSS
with H-format programmable telemetry enabled
• 3.2 Script Review• Section A – Load, dump, compare Venus Observation SPC Macro Table Load
• Load Venus Observation SPC Macro Table load (1 min)• Dump the SPC table 1 (5 min)• Compare the Venus Observation SPC Macros Table with the dump (1 min)
• Section B – Venus Observation Macro Activation• Activate Venus Observation Macro 1 (1 min)
• Section C – Venus Observation Restoration• Verify Special Processor not active (1 min)• Activate post Venus Observation Macro 2 ( 1min)
2010/2011 Venus Observation
P. 3022 Dec 2010
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3.0 Engineering Test / Installation
3.3 Standalone Testing • Objective
• To validate Venus macro installation and back-out procedure in an operational scenario without impact to operations. The Standalone Testing was performed using STScI-provided test SMS.
• DSTIF Test Bed Configuration• DMU (only one), DIUs (test configuration), CPM2• PCS Simulator, Version 51A
• 486 FSW Configuration (current on-orbit)• FSW 3.4A installed• BMIC enabled• Telemetry ‘H’ Format• Safemode tests and macros enabled for the SMS testing
• CCS Ground Test Configuration• Ground System Software – CCS Version 7.1.1.0.4• Database – O07300R1S
2010/2011 Venus Observation
P. 3122 Dec 2010
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3.0 Engineering Test / Installation
3.3 Standalone Testing (continued)• The STScI generated test SMS was run twice.• Executed IP-219, Venus Observation SPC Macros, to patch the Safemode
Responses and change the Sun Cosine Limit to support the Venus Observation• During the first run of the SMS, the acquisitions were allowed to complete
nominally. • All of the acquisitions performed as expected.
• During the second run of the SMS, the acquisitions were forced to run long in the PCS Simulator to allow the AQEXPIRE timer to fire off.
• The setting of the AQEXPIRE parameter in the GSACQ blocks was verified to be long enough to allow enough time for the acquisitions to stop and maneuver the vehicle to the Target attitude before the Moving Target tracking slews were commanded.
• Executed IP-219, Venus Observation SPC Macros, to back out the Macro changes.
• If the AQEXPIRE command fires off while the #43 (Vehicle Offset Maneuver) command is being executed a Command Reject will occur.
• This is the same situation detailed in Ops Note 1973.• It takes a very unique failure case for this to occur.
• The Vehicle will be at the correct target location if this happens and there are no Health and Safety concerns. The acquisition will terminate correctly.
2010/2011 Venus Observation
P. 3222 Dec 2010
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3.0 Engineering Test / Installation
STIS Venus Observations•Test SMS (STISITDF) was generated and delivered to the SISE to validate special commanding and confirm the CCD observations with the TDF response disabled, allowing the exposure to continue regardless of the results of the GSAcq
•All external CCD exposures are normally taken with TDF response enabled.
•Test SMS was executed on VSTIF on 12-2-10•NSSC-1 FSW BQ 9.0.8•STIS FSW CS5.01/MIE4.4 (ov0008) •Bus monitor tool enabled for logging•STIS Ops Benches in Safe mode prior to test start•SMS was executed twice, once with TDF enabled and once with TDF disabled•SMS transitioned STIS from Safe to Operate and then performed two CCD images. One with TDF response disabled and one with TDF Response Enabled.•CCD Images were then dumped and headers reviewed to verify CCD Shutter performance.
2010/2011 Venus Observation
P. 3322 Dec 2010
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3.0 Engineering Test / Installation
STIS Venus Observations• Summary
• STIS CCD Shutter opens and closes normally regardless of TDF state when TDF response in disabled.
• Additional manual testing of STIS CCD shutter response to TDF state toggling while exposure in progress was also performed.
• CCD Shutter remained open.
2010/2011 Venus Observation
P. 3422 Dec 2010
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3.0 Engineering Test / Installation
3.4 Timeline Review• 1st Opportunity to load Venus Observation Macros @ 356/20:28 – 20:55• 2nd Opportunity to load Venus Observation Macros @ 356/21:56 – 22:37 • 1st Opportunity to activate Macro 1 @ 361/19:40 – 19:56• 2nd Opportunity to active Macro 1 @ 361/21:36 – 22:01• Slew to Venus+5º starts at 361/22:30• Slew away from the Venus activities starting at 362/02:03• 1st Opportunity to restore via Macro 2 @ 362/02:35 – 02:42• 2nd Opportunity to restore via Macro 2 @ 362/03:35 – 03:40
2010/2011 Venus Observation
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3.0 Engineering Test / Installation – MEGG review
PLACE HOLDER
1st opportunity to load Venus Observation Macros
2010/2011 Venus Observation
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3.0 Engineering Test / Installation – MEGG review
2nd opportunity to load Venus Observation Macros1st op. for NCCI load
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3.0 Engineering Test / Installation – MEGG review
1st opportunity to Activate Macro 1
2010/2011 Venus Observation
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3.0 Engineering Test / Installation – MEGG review
2nd opportunity to Activate Macro 1
2010/2011 Venus Observation
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3.0 Engineering Test / Installation – MEGG review
2010/2011 Venus Observation
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3.0 Engineering Test / Installation – MEGG review
2010/2011 Venus Observation
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3.0 Engineering Test / Installation – MEGG review
1st opportunity to execute restore macro 2
2nd opportunity to execute restore macro 2
2010/2011 Venus Observation
P. 4222 Dec 2010
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3.0 Engineering Test / Installation – MEGG review
2010/2011 Venus Observation
P. 4322 Dec 2010
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4.0 Monitoring and System Impacts
4.1 On-Orbit Validation / Monitoring• DMS will validate successful load of the (safemode) configuration macro• PCS will monitor OBAD acq• PI will validate data prior to Jan observations
4.2 System Impacts• PCS, SI, EPS: None• DMS, I&C
• Mat LEI turned off for a 9 hour window• THERMAL:
• Waiver of CARD 3.1.7.3 (see Section 5.1)• SAFING:
• Temporary modification to responses of six safemode tests• In FSW, reducing the Sunpoint Sun protection threshold limit to provide
margin for Venus Observation• PSEA BOD circuitry provides redundancy against Sun in the
boresight within 38º
2010/2011 Venus Observation
P. 4422 Dec 2010
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4.0 Monitoring and System Impacts
4.3 Supporting Operations Changes• None
4.4 Supporting PRD Changes• None
4.5 Subsystem Training Module Changes• None
2010/2011 Venus Observation
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5.0 Constraints and Restrictions Review
5.1 CARD• One waiver is required:
• 3.1.7.3 HST Sun Pointing Limits• The HST sun angle as measured from the +V1 axis should not go below 50°.
Excursions could raise the OTA baffle temperatures above their bake-out temperatures and out-gassing may result.
• 46° is required for the Venus observation• EM MOSES 1067 outlines the thermal impacts to prolonged sun angles <50°
• A nominal Venus Observation as outlined here should not violate any temperature limits
• An inertial hold safemode at sun angles <50° has the potential to violate OTA baffle temperature limits
• All contingency procedures comply with the CARD
5.2 OLD• No operations limitations violated or waivers required in the procedures
• All activities for installation handled by FSW code design and procedure
2010/2011 Venus Observation
P. 4622 Dec 2010
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6.0 Contingency Planning
6.1 Vehicle Contingencies• HST safing while pointed within the SAZ
• Concern• If HST were to enter inertial hold safe mode while pointed within the
SAZ, that could violate thermal temperature limits on the OTA baffles• After 15 minutes in sunlight at 46° sun angle the OTA baffles exceed
their 121°C bake-out temperature limit (EM MOSES 1067)• Precautions
• Redirecting certain safemode tests such that conditions that would normally lead to inertial hold leads to software sun point safe mode instead to prevent Sun in boresight
• CDH Safing event• Still activate observation macro• Allow SMS to continue• No observation
2010/2011 Venus Observation
P. 4722 Dec 2010
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6.0 Contingency Planning
6.1 Vehicle Contingencies• FGS exposure to Venus
• Concern• If the attitude error is large enough, an FGS could possibly see Venus
and cause potential bright light exposure to the FGS photo-multiplier tubes.
• Precautions• Choose guide stars that are as far as possible from Venus• The chosen guide star is magnitude 12.4 and will be about 15.5
arcminutes from Venus
2010/2011 Venus Observation
P. 4822 Dec 2010
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6.0 Contingency Planning
6.1 Vehicle Contingencies• FGS exposure to Venus
• Analysis• Goodrich assessed PMT damage should a worst-case event occur
resulting in an attempted acquisition of Venus with an FGS (ref: Goodrich Memo A16-ST-2254)
• Goodrich reports the short-term effect of the Venus acquisition would be the temporary incapacitation of the PMTs due to dark count elevation. While the exact value is not available for the given intensity, literature quotes range from several to 48 hours for recovery (for any target).
• Goodrich performed a relative assessment of the long-term effects of Coulomb draw (charge depletion) while attempting to acquire Venus with an FGS. While it is hard to determine exactly how the FGS would behave if it attempted to perform an acquisition on Venus, depending on how long it spends with Venus in the FOV, you could see a decrease in reliability from 1-3%.
• Response• If SEs determine that there is a large attitude error, Software Sunpoint
may be commanded via COP 6.01
2010/2011 Venus Observation
P. 4922 Dec 2010
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6.0 Contingency Planning
6.1 Vehicle Contingencies• Code Red GSFC Inclement Weather Situation
• Venus observation will be executed from SMS• If potential weather situation is predicted, an early execution of the
configuration macro will be performed during good weather• If sudden storm occurs, SEs will make best effort to support from OSR or via
phone
2010/2011 Venus Observation
P. 5022 Dec 2010
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7.0 Engineering Support Requirements• 7.1 Personnel
• Test Conductor – DMS Ben Teasdel• FSW- Briand Vreeland • Systems Management- Wayne Burdick• STIS Steve Arslanian• PCS Dan Smith• Normal SE on-call personnel• FOT - normal shift
• 7.2 Communications / Data• FOT will be briefed before the test.• Circuit assignments:
• R/T Ops COORD Primary circuit for Test Conductor and FOT• HST COORD Backup loop to FOT
• Ops Requests (OR’s) • 18990-4 – “Load Venus Observation Macros” • 18991-1 – “Venus Observation Patch”
• Flash Reports will be issued following completion of the test.• FRR Material is available on EDOCS web site
• http://edocs.hst.nasa.gov/MOP/Shared%20Documents/FRRpage.htm
2010/2011 Venus Observation
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7.0 Engineering Support Requirements
7.3 CCS• Prime Ops on “F” string• Back-up Ops on “D” string• CCS Release 8.1.0.0.14• PRD O07300R1S• FSW loads have been delivered to both prime and back-up strings
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8.0 Liens/Issues• None
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9.0 Forward Plan
• Ops Briefing Jan 19th
• PI to analyze data from December observation prior to this briefing to ensure observation was successful and enable refinements of January observation to improve data gathering.
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10.0 Actions
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Backup Information
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TargetVisibility
GS Pair Acqat Venus+5D
Slew toVenus
TargetVisibility
Shadow
Single GSAcq at Venus
ObserveVenus
Slew toVenus+5D
ObserveVenus+5D
GS PairAcq atVenus+5D
Observing Strategy Details
TargetVisibility
Shadow
Slew toVenus
Single GSAcq at Venus
Observe Venus
Slew toVenus+5D
ObserveVenus+5D
GS PairAcq atVenus+5D
–Display as seen from HST
2010/2011 Venus Observation
P. 5722 Dec 2010
LOGO.049
–Sun
–Venus
–Earth
HST’s View of Venus (t = 0)
–Venus is in Earth occultation. The Sun is not. HST would be pointed at Venus+5D at this time.
–Sun
–Venus
–Venus+5D–Earth
–Sun
–Venus
–Venus+5D–Earth
2010/2011 Venus Observation
P. 5822 Dec 2010
LOGO.049
HST’s View of Venus (t = 5 min)
–The Sun is moving toward setting.
2010/2011 Venus Observation
P. 5922 Dec 2010
LOGO.049
HST’s View of Venus (t = 10 min)
–The Sun is moving toward setting. The terminator becomes visible on the Earth.
2010/2011 Venus Observation
P. 6022 Dec 2010
LOGO.049
HST’s View of Venus (t = 15 min)
–The Sun is very close to setting.
2010/2011 Venus Observation
P. 6122 Dec 2010
LOGO.049
HST’s View of Venus (t = 20 min)
–The Sun has set. HST is now in the Earth’s shadow.
2010/2011 Venus Observation
P. 6222 Dec 2010
LOGO.049
HST’s View of Venus (t = 25 min)
–Venus is very close to rising. At about this time, HST will begin its slew from Venus+5D to Venus
2010/2011 Venus Observation
P. 6322 Dec 2010
LOGO.049
HST’s view of Venus (t = 30 min)
–Venus has risen. At about this time, HST will complete its slew to Venus; and the guide star acquisition will begin.
2010/2011 Venus Observation
P. 6422 Dec 2010
LOGO.049
HST’s View of Venus (t = 35 min)
–At about this time, the guide star acquisition will finish; and the science observation will begin.
2010/2011 Venus Observation
P. 6522 Dec 2010
LOGO.049
HST’s View of Venus (t = 40 min)
–At about this time, the science observation will finish; and the slew to Venus+5D will begin.
2010/2011 Venus Observation
P. 6622 Dec 2010
LOGO.049
HST’s View of Venus (t = 45 min)
–The Sun is very close to rising.
2010/2011 Venus Observation
P. 6722 Dec 2010
LOGO.049
HST’s View of Venus (t = 50 min)
–The Sun has risen. HST is now out of the Earth’s shadow. The slew to Venus+5D finishes a couple of minutes after sunrise.