1. Venus Observations Flight Readiness Review (HST Program 8659) 21 January 2003 Post-FRR release – 24 Jan 2003

2. 2003 Venus Observation P. 2 24 Jan 2003 1.0 Introduction/Overview (Tony Roman) 2.0 FSW, S/C H/W Changes and Implementation (Brian Vreeland) 2.1FSW and/or S/C H/W Functional Changes 2.2FSW Software Structure/Resource Changes 2.3Supporting Ground System Changes 2.4Supporting Documentation Changes 2.5Release Messages 2.6Unit and Build Level Testing/Results 2.7System Level Testing/Results 3.0Engineering Test / Installation (Regalado, Haskins) 3.1Overview and Initial Conditions 3.2Script Review 3.3Differences between Flight and Test Configurations 3.4Operations Acceptance Testing/Results 3.5Timeline Review - MEGG Agenda

3. 2003 Venus Observation P. 3 24 Jan 2003 Agenda 4.0 Monitoring and System Impacts (Craig Tyler) 4.1On-orbit Validation / Monitoring 4.2System Impacts 4.3Supporting Operations Changes 4.4Supporting PRD Changes 4.5Training Module Changes 5.0 Constraints and Restrictions Review (Craig Tyler) 5.1CARD 5.2OLD 6.0 Contingency Planning (Tyler, Roman) 6.1 Vehicle Contingencies 6.2Observation Contingencies 7.0 Engineering Support Requirements(Craig Tyler) 7.1Personnel 7.2Communications / Data 7.3CCS 8.0Liens / Issues(Craig Tyler) 9.0 Actions

4. 2003 Venus Observation P. 4 24 Jan 2003 Engineering Team STScI - Tony Roman, Merle Reinhart, Alan Patterson OTA - Mike Wenz, Dennis Crain, Art Bradley DMS – Jessica Regalado FSW – Liher Lu, Mike Schaeffer, Brian Vreeland, Bill Keksz, Shirley Duhaney PCS – John Wirzburger EPS – Stan Krol I&C – Harry Wynn SI – Scott Swain Thermal – Christine Cottingham Safing – Ed Moy HIT – Stuart Bozievich Operations – Pataro, Cooper VEST Team Systems Management – Sujee Haskins, Randy Stevens, Craig Tyler

5. 2003 Venus Observation P. 5 24 Jan 2003 1.0 Introduction / Overview ¤Objectives 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 ¤Background Why is Venus Special? »Venus is about 47 degrees from the Sun »HST is normally not permitted to point within 50 degrees of the Sun Venus Observing Program History »In cycle 4, HST observed Venus with GHRS and WFPC2 (GO programs 4518 and 5783) »In cycle 6, 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 Director shortly after phase 2 submission. »In cycle 7, there was a GTO/STIS program (7581) to observe Venus. Much implementation work was done, but the program was then withdrawn by the PI.

6. 2003 Venus Observation P. 6 24 Jan 2003 1.0 Introduction / Overview ¤Background (continued) Venus Observing Program History »In cycle 9, the TAC approved GO program 8659 to observe Venus. This program was planned for June 2001 but did not execute due to the failure of STIS side 1 electronics. »Program 8659 is now replanned for January 26, 2003 ¤Scientific Goals High resolution STIS spectrum of Lyman-  Assess the abundance of deuterium in the Venus atmosphere Constrain models of Venus atmosphere and climate evolution ¤Observing Strategy Observe while Venus is near maximum elongation »In cycle 11, there are two 10 day long windows separated by 6 months Observe while HST is in Earth’s shadow »A window of 11-13 minutes per orbit One HST orbit is sufficient to conduct observation Generic TDRSS scheduling will be employed »Real-time contacts may not be available during the observation

7. 2003 Venus Observation P. 7 24 Jan 2003 1.0 Observing Strategy Details ¤Which elongation? Eastern: August 2002, Western: January 2003 Both are possible, but Western is easier ¤Eastern versus Western Elongation Target Visibility Shadow Target Visibility Shadow Eastern Elongation: Western Elongation:

8. 2003 Venus Observation P. 8 24 Jan 2003 1.0 Observing Strategy Details ¤Initial GS Acq at Venus+5 º A pointing 5 degrees from Venus and 51.01 degrees from the Sun. Minimizes slew distance to Venus Precautionary measure to protect against large pointing error after slew ¤GS Acq at Venus ¤Venus science observation 4.25m exposure STIS auto wave cal disabled ¤Venus+5 º Observation  Geocoronal Lyman-  foreground and interplanetary Lyman-  background. 16m exposure For subtraction from Venus Lyman-alpha line Target Visibility GS Pair Acq at Venus+5º Slew to Venus Target Visibility Shadow Single GS Acq at Venus Observe Venus Slew to Venus+5º Observe Venus+5º GS Pair Acq at Venus+5º

9. 2003 Venus Observation P. 9 24 Jan 2003 1.0 Observing Strategy Details ¤Venus Data Apparent magnitude: -4.4 Venus Appearance at Observation Sun angle: 46.00 degrees Surface brightness: +1.5 (average for 1 square arcsecond of illuminated portion of disk) Apparent diameter: 21.12 arcseconds Phase angle: 81.24 degrees ¤While slewing away from Venus, the telescope will be exposed to sunlight while pointed inside the Solar Avoidance Zone for 2 minutes 30 seconds ¤Because this observation requires the telescope to be pointed close to the Sun while in the Earth’s shadow, a macro was developed to change the Safemode response from Inertial Hold to Software Sunpoint. The Sunpoint sun angle limit was also changed from 46 degrees to 42 degrees to provide a margin for the expected 46 degrees at closest approach.

10. 2003 Venus Observation P. 10 24 Jan 2003 2.0 FSW, S/C H/W Changes and Implementation 2.1 FSW and/or S/C H/W Functional Changes DCR 1052 Venus Observation SPC Macros Load File - QVENUSB_0.TAB Activation Macro at SPC Address 13000 Set up six TMDIAGS to monitor the six Safe Test Response Modifications 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 Perform BMIC management for the modified Tables De-Activation Macro at SPC Address 13100 Set up six TMDIAGS to monitor the six Safe Test Response Modifications Modify the Sunpoint Sun Cosine Limit from 42 to 46 degrees Modify six Safe Test Responses from Software Sunpoint to Inertial Hold Perform BMIC management for the modified Tables IP-33_Venus_Obs_Procedure.doc Load QVENUSB_0.TAB, using TMDIAGS to verify the load Execute the Activation and De-Activation Macros with additional TMDIAG of Sun Cosine Limit for Verification.

11. 2003 Venus Observation P. 11 24 Jan 2003 2.0 FSW, S/C H/W Changes and Implementation 2.2 FSW Structure/Resource Changes - None 2.3 Supporting Ground System Changes - None 2.4 Supporting Documentation Changes - None 2.5 Release Messages SSM064 IP-33_Venus_Obs_Procedure.doc PNM_2002343125203.TXT

12. 2003 Venus Observation P. 12 24 Jan 2003 2.0 FSW, S/C H/W Changes and Implementation 2.6 Unit and Build Level Testing/Results - None Needed 2.7 System Level Testing/Results - All Tests Passed LMBLAB tests using: FV022a with Current On-orbit RAM Patches Flight DIU Addresses CCS Data Base O06100, CCS Release d4.0.1.0.24 PC-PCSSIM 43c LMBLAB Checkout of IP-33 Installation and Backout Procedures and Macros Six tests that place HST at Venus Observing Attitude and fail Safe Mode Tests to verify Sunpoint instead of Inertial Hold One test that places HST Boresight between the Normal Mode Sun Cosine Limit (32 deg.) and Venus Macro modified Sunpoint Mode Sun Cosine Limit (42 deg.), then go to Sunpoint to force a failure of the modified Limit.

13. 2003 Venus Observation P. 13 24 Jan 2003 3.0 Engineering Test / Installation 3.1 Overview and Initial Conditions SSM486 Flight Software Version 2.2 Release A, plus on-board patches, are currently executing in VSS with H-Format programmable telemetry enabled 3.2 Script Review Set up TMDIAGs to verify Venus SPC macros (1 min) Uplink Venus SPC macros via table load (1 min) Verify load via TMDIAGs (1 min) Set up TMDIAGs to verify current sun protect limit (1 min) Execute Venus macro and verify change in safing response via TMDIAGs (4 min). »Uses Special Processor with pointer value 13000 »TMDIAGs are loaded via Macro Load TMDIAG to verify new sun protection limit (1 min) After completion of Venus Observation event, execute SPC macro to reset the safing response back to Inertial Hold (3 min) »Uses special Processor with pointer value 13100 Set up TMDIAG to verify reset of sun protection limit back to it’s original limit (1 min)

14. 2003 Venus Observation P. 14 24 Jan 2003 3.0 Engineering Test / Installation 3.3 FSW/Operations Acceptance Testing and Results Objective: To validate Venus macro installation and back-out procedure in an operational scenario without impact to operations. The OAT was performed using STScI-provided test SMS. VEST Configuration for 01/08/03 (008) »NSSC-I/CDH1 FSW 7.5.4 (Flight version of Safing/suspend RTCs set is loaded) »DMU (A side configuration), DIUs (flight configuration), CPM1 »PCS Simulator (Alpha) version 42B »PSEA powered on 486 FSW Configuration (current on-orbit) »FSW 2.2A installed with latest on-orbit patches »BMIC enabled »KA enabled »Telemetry ‘H’ Format »Safemode tests and macros enabled for the SMS testing CCS Ground Test Configuration »Primary, B-string: Ground System Software - CCS Version 4.01 C String, Database - PRD-O06100TQ1

15. 2003 Venus Observation P. 15 24 Jan 2003 3.0 Engineering Test / Installation 3.3 FSW/Operations Acceptance Testing and Results (continued) Test Sequence: »Load and execute Venus macro to configure safe mode response during Venus observation »Regression test during Venus observing period »Executed and validated the Venus back-out procedure »Reactivate Venus macro and initiate Inertial Hold Safemode failure to verify safe mode response Test Results »The Venus Observation installation and back-out procedures were successfully installed and no problems were encountered during regression testing 3.4 Differences Between Test and Flight Configurations NSCC-I in Normal Mode with standard PIT Interface enabled. NSSC-I stored commanding not used. »No Impact Used simulated EPS system modeled in PCSSIM »Battery Pressure Safe Test was not enabled »No Impact

16. 2003 Venus Observation P. 16 24 Jan 2003 3.0 Engineering Test / Installation 3.5 Timeline Review 1 st Installation Opportunity @ 026/05:54:38 – 026/06:12:50 2 nd Installation Opportunity for steps 1-4 @ 026/06:26:00 – 026/07:10:57 Slew to Venus+5º starts at 026:08:15:28 Slew away from the Venus activities starting at 026:10:56:08 1 st Backout Opportunity @ 026/10:59:27 – 026/11:30:30 2nd Backout Opportunity @ 026/12:40:15 - 026/13:14:14 Scheduling Information »No special commanding is required for STIS »No special commanding is required for other SIs

17. 2003 Venus Observation P. 17 24 Jan 2003 3.0 Engineering Test / Installation - MEGG 1 st Installation Op.

18. 2003 Venus Observation P. 18 24 Jan 2003 3.0 Engineering Test / Installation - MEGG 2 nd Installation Opportunity

19. 2003 Venus Observation P. 19 24 Jan 2003 3.0 Engineering Test / Installation - MEGG

20. 2003 Venus Observation P. 20 24 Jan 2003 3.0 Engineering Test / Installation - MEGG 1 st Opportunity to backout

21. 2003 Venus Observation P. 21 24 Jan 2003 3.0 Engineering Test / Installation - MEGG 2 nd opportunity to backout

22. 2003 Venus Observation P. 22 24 Jan 2003 4.0 Monitoring and System Impacts 4.1 On-Orbit Validation / Monitoring DMS will validate successful load of the safemode configuration macro 4.2 System Impacts PCS, DMS, I&C, SI, EPS: None OTA: See contingency section 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

23. 2003 Venus Observation P. 23 24 Jan 2003 4.0 Monitoring and System Impacts 4.3 Supporting Operations Changes Ops Requests »Ops Request #16894-0, Venus Observation Patch »Ops Request #16893-0, Venus Observation Contingency to Command SWSP 4.4 Supporting PRD Changes None 4.5 Subsystem Training Module Changes None

24. 2003 Venus Observation P. 24 24 Jan 2003 5.0 Constraints and Restrictions Review 5.1 CARD The following operations constraints or restrictions are met: »2.1.4.4 Sunlight on Fixed Head Star Tracker (FHST) Shutter »3.1.4.8 PCS FHST Protection From Earth, Moon, Sun 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 activities for installation handled by FSW code design and procedure »3.1.9.36 Memory Load Using STFS Type 9 Command »3.1.9.38 Telemetry Diagnostic Address Sampling »3.1.9.41 HST 486 Flight Software Background Memory Integrity Check 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

25. 2003 Venus Observation P. 25 24 Jan 2003 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

26. 2003 Venus Observation P. 26 24 Jan 2003 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. The only feasible scenario is an RGA flex lead failure that leaves the gyro online. »Precautions Choose guide stars that are as far as possible from Venus The chosen guide star is magnitude 11.1 and will be about 16.2 arcminutes from 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 6.01A

27. 2003 Venus Observation P. 27 24 Jan 2003 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 safing macro will be performed during good weather »If sudden storm occurs, SEs will make best effort to support from SMOR or via phone

28. 2003 Venus Observation P. 28 24 Jan 2003 6.0 Contingency Planning 6.2 Observation Contingencies Problem Shortly Before Observation »Concern An unrelated problem may threaten the Venus observing window In cycle 4, the Venus observation was originally lost due to an unrelated safing; but it was quickly replanned and executed successfully In May 2001, the current program was delayed due to the failure of the STIS side 1 electronics »Remedy The current Venus observation could probably be rescheduled within a couple of weeks after January 26 A reduction of exposure time or an additional orbit would be required The Sun angle would be reduced to 44-45 degrees There might be conflicts with other time critical observations At 44° sun angle there would be 8 minutes of sunlight allowed before the OTA baffles reach their 121 bake-out limits (EM MOSES 1067) 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 In cycle 4, additional FHST maps were also inserted by GSFC; but now there are automatic FHST maps, so this is not an issue A guide star acquisition test was planned in advance –Guide star ID is 00624100797. –Test successfully completed on July 15, 2002 If Guide Star failure, then shutter will not open

29. 2003 Venus Observation P. 29 24 Jan 2003 7.0 Engineering Support Requirements 7.1Personnel Test Conductor - DMS FSW, Safing, PCS, and Systems Management – monitoring in SMOR GSM and Systems Administration– supporting SMOR Normal SE on-call personnel FOT - normal shift 7.2Communications / Data Operations briefing will be conducted on CCL-50 starting at 026/06:00 GMT (01:00 AM EST) Circuit assignments: »CCL-50Primary circuit for Test Conductor and FOT »CCL-56SE to FC circuit FRR Material is available on EDOCS web site http://edocs1.hst.nasa.gov/doc/publish/mop/misopdoc.htm 7.3CCS Prime Ops on “A” string Back-up Ops on “G” string CCS Release 4.01 OPS PRD O06100Q FSW loads have been delivered to both prime and back-up strings

30. 2003 Venus Observation P. 30 24 Jan 2003 8.0 Liens/Issues None

31. 2003 Venus Observation P. 31 24 Jan 2003 9.0 Actions Tyler – Review potential Shuttle dual-shift operations impact on Venus observations – No conflicts Tyler – E-mail Final MEGG to Chris Wilkinson for review – Completed 1/23/03 Regalado – Review final SMS/MEGG and scheduled forward/return, especially from 09:45 to 10:05 GMT, and seek additional coverage, if needed – Completed 1/22/03 DMS, FSW, Safing, PCS, and Systems Management – verify access to CCS prior to weekend support – Completed 1/21/03 TCS – review heating on top bays during previous Venus observations »The past thermal analysis performed for the Venus observation only addressed the heating of the OTA baffles and light shield. There has been no formal analysis on the heating of the equipment shelf due to high sun angles. Christine Cottingham reports that it will not be a problem as long as the aperture door is closed at sun angles < 50 degrees during inertial hold for the following reasons: The tops of the equipment bays are double blanketed, externally and internally, which is more insulated than a lot of bay doors that get sun all the time. No equipment is attached to the tops of the bays. PCS thinks we might have seen some short excursions to high sun angles during the 1999 ZGSP, and no drastic temperature changes were seen in the bays. At high sun angles the bay doors cool off due to low sun incidence on the bay doors. This would provide a sink for the bays to reject extra heat. »If an inertial hold is seen at high sun angles, TCS would closely monitor the situation. If temperatures were trending to where TCS thought there would be a problem, the spacecraft could be commanded to software sunpoint. For future Venus observations, unless there is a clear science gain schedule visits during daytime/weekday