Venus Observations
Flight Readiness Review
(HST Program 12433)
22 December 2010
2010/2011 Venus Observation
Agenda
1.0 Venus Observation
Tony Roman
2.0 FSW, S/C H/W Changes and Implementation
Brian Vreeland
2.1
2.2
2.3
2.4
2.5
2.6
2.7
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 Overview and Initial Conditions
3.2 Script Review
3.3 Standalone Testing
3.4 Timeline Review
3.5 MEGG
22 Dec 2010
Ben Teasdal
Ben Teasdal
Mike Wenz / Steve
Arslanlian
Ben Teasdal
Ben Teasdal
P. 2
2010/2011 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
Wayne Burdick
Vehicle Contingencies
Other Contingencies
7.0 Engineering Support Requirements
7.1
7.2
7.3
Wayne Burdick
CARD
OLD
6.0 Contingency Planning
6.1
6.2
Wayne Burdick
Wayne Burdick
Personnel
Communications / Data
CCS
8.0 Liens / Issues
Wayne Burdick
9.0 Forward Plan
Wayne Burdick
10.0 Actions
Wayne Burdick
22 Dec 2010
P. 3
2010/2011 Venus Observation
Engineering Team
STScI - Tony Roman, Merle Reinhart, Alan Welty, Charles Proffitt
OTA - Mike Wenz, Dennis Crain, Art Bradley
DMS / I&C– Ben Teasdel and Jessica Regalado
FSW – Brian Vreeland, Norm Roy, Shirley Duhaney, Suzanne Benedict, Susan
Lien, Vicki van Duyl, Anthony Wells, Clive Caldwell, Linda Mitchell
Payload FSW - Dennis Garland
PCS – Dave Murphy
EPS – Stan Krol
SI – Scott Swain
Thermal – Josh Abel
Safing – Ed Moy
Operations – Lynn Bassford, Joe Cooper
Systems Management – Wayne Burdick
22 Dec 2010
P. 4
2010/2011 Venus Observation
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.
22 Dec 2010
P. 5
2010/2011 Venus Observation
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
22 Dec 2010
P. 6
2010/2011 Venus Observation
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
22 Dec 2010
P. 7
2010/2011 Venus Observation
Observing Strategy Details
Target Visibility
Target Visibility
Shadow
Target Visibility
Shadow
GS Pair Acq
at Venus+5D
Observe
Slew to
OBAD
Venus
Venus
Observe
GS Pair Acq at Slew to
OBAD
Venus
Venus
Venus+5D
Single GS Acq Slew to
Venus +5D
at Venus
•
GS Pair Acq at
Venus+5D
Single GS Acq Slew to
Venus +5D
at Venus
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
22 Dec 2010
P. 8
2010/2011 Venus Observation
Observing Strategy Details
Target Visibility
Target Visibility
Shadow
Target Visibility
Shadow
GS Pair Acq
at Venus+5D
Observe
Slew to
OBAD
Venus
Venus
Observe
GS Pair Acq at Slew to
OBAD
Venus
Venus
Venus+5D
Single GS Acq Slew to
Venus +5D
at Venus
•
•
GS Pair Acq at
Venus+5D
Single GS Acq Slew to
Venus +5D
at Venus
Single GS Acq at Venus
•
Saves about a minute versus pair acquisition
Venus science observation
•
153s exposure
•
STIS auto wave cal disabled
22 Dec 2010
P. 9
2010/2011 Venus Observation
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
22 Dec 2010
P. 10
2010/2011 Venus Observation
Vital Statistics
Observation
Science
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 FGS1
on 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
22 Dec 2010
P. 11
2010/2011 Venus Observation
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
22 Dec 2010
P. 12
2010/2011 Venus Observation
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
22 Dec 2010
P. 13
2010/2011 Venus Observation
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
22 Dec 2010
P. 14
2010/2011 Venus Observation
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%.
22 Dec 2010
P. 15
2010/2011 Venus Observation
HST FOV
22 Dec 2010
P. 16
2010/2011 Venus Observation
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.
22 Dec 2010
P. 17
2010/2011 Venus Observation
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.
22 Dec 2010
P. 18
2010/2011 Venus Observation
2010 Venus Observations
GSACQ Adjustments
Mike Wenz for Merle Reinhart
22 Dec 2010
P. 19
2010/2011 Venus Observation
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.
22 Dec 2010
P. 20
2010/2011 Venus Observation
GSACQ Time Reduction
Specifics – 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
22 Dec 2010
• 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
P. 21
2010/2011 Venus Observation
GSACQ Time Reduction
Specifics – 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.
22 Dec 2010
P. 22
2010/2011 Venus Observation
2.0 FSW, S/C H/W Changes and Implementation
FSW – Brian Vreeland
22 Dec 2010
P. 23
2010/2011 Venus Observation
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
•
•
•
•
22 Dec 2010
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
P. 24
2010/2011 Venus Observation
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
22 Dec 2010
P. 25
2010/2011 Venus Observation
2.0 FSW, S/C H/W Changes and Implementation
FSW Structure/Resource Changes – None
Supporting Ground System Changes - None
Supporting Documentation Changes - None
Release Messages
• SSM212
• IP-219_Venus_Observation_Macros.docx
• PNM_20103473812.TXT
2.6 Unit and Build Level Testing/Results
• None Needed
2.2
2.3
2.4
2.5
22 Dec 2010
P. 26
2010/2011 Venus Observation
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
22 Dec 2010
P. 27
2010/2011 Venus Observation
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
•
22 Dec 2010
N/A
P. 28
2010/2011 Venus Observation
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)
22 Dec 2010
P. 29
2010/2011 Venus Observation
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 STScIprovided 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
22 Dec 2010
P. 30
2010/2011 Venus Observation
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.
22 Dec 2010
P. 31
2010/2011 Venus Observation
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.
22 Dec 2010
P. 32
2010/2011 Venus Observation
3.0 Engineering Test / Installation
STIS Venus Observations
•
22 Dec 2010
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.
P. 33
2010/2011 Venus Observation
3.0 Engineering Test / Installation
3.4 Timeline Review
•
•
•
•
•
•
•
•
22 Dec 2010
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
P. 34
2010/2011 Venus Observation
3.0 Engineering Test / Installation – MEGG review
PLACE HOLDER
1st opportunity to load Venus Observation Macros
22 Dec 2010
P. 35
2010/2011 Venus Observation
3.0 Engineering Test / Installation – MEGG review
2nd opportunity to load Venus Observation Macros
1st op. for NCCI load
22 Dec 2010
P. 36
2010/2011 Venus Observation
3.0 Engineering Test / Installation – MEGG review
1st opportunity to Activate Macro 1
22 Dec 2010
P. 37
2010/2011 Venus Observation
3.0 Engineering Test / Installation – MEGG review
2nd opportunity to Activate Macro 1
22 Dec 2010
P. 38
2010/2011 Venus Observation
3.0 Engineering Test / Installation – MEGG review
22 Dec 2010
P. 39
2010/2011 Venus Observation
3.0 Engineering Test / Installation – MEGG review
22 Dec 2010
P. 40
2010/2011 Venus Observation
3.0 Engineering Test / Installation – MEGG review
1st opportunity to execute restore macro 2
22 Dec 2010
2nd opportunity to execute restore macro 2
P. 41
2010/2011 Venus Observation
3.0 Engineering Test / Installation – MEGG review
22 Dec 2010
P. 42
2010/2011 Venus Observation
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
22 Dec 2010
P. 43
2010/2011 Venus Observation
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
22 Dec 2010
P. 44
2010/2011 Venus Observation
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
22 Dec 2010
P. 45
2010/2011 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
• CDH Safing event
• Still activate observation macro
• Allow SMS to continue
• No observation
22 Dec 2010
P. 46
2010/2011 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.
• 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
22 Dec 2010
P. 47
2010/2011 Venus Observation
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
22 Dec 2010
P. 48
2010/2011 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
configuration macro will be performed during good weather
• If sudden storm occurs, SEs will make best effort to support from OSR or via
phone
22 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
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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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Observing Strategy Details
Observe
Venus+5D
Target
Target
Target
Visibility
Visibility
Visibility
Shadow
–Display as seen
from HST
Shadow
GS Pair Acq
at Venus+5D
Slew to
Venus
Observe
Venus
Single GS
Acq at Venus
22 Dec 2010
Slew to
Venus+5D
Observe
Venus+5D
GS Pair
Acq at
Venus+5D
Slew to
Venus
Observe
Venus
Single GS
Acq at Venus
Slew to
Venus+5D
GS Pair
Acq at
Venus+5D
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HST’s View of Venus (t = 0)
–Earth
–Earth
–Earth
–Venus+5D
–Venus+5D
–Sun
–Sun
–Sun
–Venus
–Venus
–Venus
–Venus is in Earth occultation. The Sun is not. HST would be pointed at
Venus+5D at this time.
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HST’s View of Venus (t = 5 min)
–The Sun is moving toward setting.
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HST’s View of Venus (t = 10 min)
–The Sun is moving toward setting. The terminator becomes visible on the Earth.
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HST’s View of Venus (t = 15 min)
–The Sun is very close to setting.
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HST’s View of Venus (t = 20 min)
–The Sun has set. HST is now in the Earth’s shadow.
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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
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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.
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HST’s View of Venus (t = 35 min)
–At about this time, the guide star acquisition will finish; and the science
observation will begin.
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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.
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HST’s View of Venus (t = 45 min)
–The Sun is very close to rising.
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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.
22 Dec 2010
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