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Venus Observations
Flight Readiness Review
(HST Program 8659)
21 January 2003
Post-FRR release – 24 Jan 2003
2003 Venus Observation
Agenda
1.0 Introduction/Overview
2.0 FSW, S/C H/W Changes and Implementation
2.1
2.2
2.3
2.4
2.5
2.6
2.7
24 Jan 2003
(Brian Vreeland)
FSW and/or S/C H/W Functional Changes
FSW Software Structure/Resource Changes
Supporting Ground System Changes
Supporting Documentation Changes
Release Messages
Unit and Build Level Testing/Results
System Level Testing/Results
3.0 Engineering Test / Installation
3.1
3.2
3.3
3.4
3.5
(Tony Roman)
(Regalado, Haskins)
Overview and Initial Conditions
Script Review
Differences between Flight and Test Configurations
Operations Acceptance Testing/Results
Timeline Review - MEGG
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2003 Venus Observation
Agenda
4.0 Monitoring and System Impacts
4.1
4.2
4.3
4.4
4.5
On-orbit Validation / Monitoring
System Impacts
Supporting Operations Changes
Supporting PRD Changes
Training Module Changes
5.0 Constraints and Restrictions Review
5.1
5.2
(Tyler, Roman)
Vehicle Contingencies
Observation Contingencies
7.0 Engineering Support Requirements
7.1
7.2
7.3
(Craig Tyler)
CARD
OLD
6.0 Contingency Planning
6.1
6.2
(Craig Tyler)
(Craig Tyler)
Personnel
Communications / Data
CCS
8.0Liens / Issues
(Craig Tyler)
9.0 Actions
24 Jan 2003
P. 3
2003 Venus Observation
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
24 Jan 2003
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2003 Venus Observation
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.
24 Jan 2003
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2003 Venus Observation
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-a
• 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
24 Jan 2003
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2003 Venus Observation
1.0 Observing Strategy Details
¤ Which elongation?
• Eastern: August 2002, Western: January 2003
• Both are possible, but Western is easier
¤ Eastern versus Western Elongation
Eastern Elongation:
Target Visibility
Shadow
Target Visibility
Western Elongation:
24 Jan 2003
Shadow
P. 7
2003 Venus Observation
1.0 Observing Strategy Details
Target Visibility
Target Visibility
Shadow
GS Pair Acq at Venus+5º
Slew to Venus
¤
Initial GS Acq at Venus+5º
•
•
•
¤
¤
Observe Venus
Observe
Slew to
Venus+5º
Venus+5º
GS Pair Acq at
Venus+5º
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
•
•
¤
Single GS Acq
at Venus
4.25m exposure
STIS auto wave cal disabled
Venus+5 º Observation
 Geocoronal Lyman-a foreground and interplanetary Lyman-a background.
• 16m exposure
• For subtraction from Venus Lyman-alpha line
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2003 Venus Observation
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.
24 Jan 2003
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2003 Venus Observation
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.
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2003 Venus Observation
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
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2003 Venus Observation
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.
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2003 Venus Observation
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)
24 Jan 2003
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2003 Venus Observation
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
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2003 Venus Observation
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
24 Jan 2003
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2003 Venus Observation
3.0 Engineering Test / Installation
3.5 Timeline Review
•
•
•
•
•
•
1st Installation Opportunity @ 026/05:54:38 – 026/06:12:50
2nd 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
1st 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
24 Jan 2003
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2003 Venus Observation
3.0 Engineering Test / Installation - MEGG
24 Jan 2003
1st Installation Op.
P. 17
2003 Venus Observation
3.0 Engineering Test / Installation - MEGG
24 Jan 2003
2nd Installation Opportunity
P. 18
2003 Venus Observation
3.0 Engineering Test / Installation - MEGG
24 Jan 2003
P. 19
2003 Venus Observation
3.0 Engineering Test / Installation - MEGG
24 Jan 2003
1st Opportunity to backout
P. 20
2003 Venus Observation
3.0 Engineering Test / Installation - MEGG
24 Jan 2003
2nd opportunity to backout
P. 21
2003 Venus Observation
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
24 Jan 2003
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2003 Venus Observation
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 Jan 2003
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2003 Venus Observation
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
24 Jan 2003
» All activities for installation handled by FSW code design and procedure
P. 24
2003 Venus Observation
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
24 Jan 2003
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2003 Venus Observation
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
24 Jan 2003
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2003 Venus Observation
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
24 Jan 2003
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2003 Venus Observation
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
•
•
•
•
24 Jan 2003
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
P. 28
2003 Venus Observation
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-50
» CCL-56
Primary circuit for Test Conductor and FOT
SE to FC circuit
• FRR Material is available on EDOCS web site
http://edocs1.hst.nasa.gov/doc/publish/mop/misopdoc.htm
7.3CCS
•
•
•
•
•
24 Jan 2003
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
P. 29
2003 Venus Observation
8.0 Liens/Issues
• None
24 Jan 2003
P. 30
2003 Venus Observation
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
24 Jan 2003
P. 31