# Presentation: 020402

## Section 6

***Survey of Residual Risk***

*** ******. . . Bryant Cramer***
*NMP Implementation Manager*

***Initial Survey of Residual Risk***
***Recent Reviews Considering Residual Risk***
***Special Topics***
***Redbook Candidates***
***Launch Liens***

## Introduction

***Introduction***

***Completion of EO-1 has been significantly affected by the Red Team process***
***Red Team Charter focuses on Residual Risk***
***Consequently, the EO-1 Project has made the consideration of Residual Risk a specific part of each recent presentation***
***The involved reviews are as follows:***
***Initial Pre-Ship Review******	******December 15-17, 1999***
***Red Team Review******	******March 28-31, 2000***
***Red Team Follow-Up Meeting******	******June 13, 2000***
***Delta Pre-Ship Review******	******August 8-9, 2000***
***Flight Software Independent Assessment******	******September 8, 2000***
***Operational Readiness Review******	******October 3, 2000***
***Mission Readiness Review******	******October 5, 2000***

## Initial Pre-Ship Review

***Initial Pre-Ship Review***

***Held the initial Pre-Ship Review on 12/15-17/99***
***WARP failure had not yet occurred***
***Launch still planned for 04/13/00***
***Wanted to discuss the results of Thermal Vacuum Test #1***
***Acknowledged that considerable work remained to be completed***
***At that time, 57 specific tasks were presented as remaining work and areas of potential residual risk***
***All but one has been completed with no untoward outcomes***
***The remaining task, the Launch Dress Rehearsal, normally occurs a few days before launch and is scheduled by KSC***

## Initial Survey of Residual Risk

***Initial Survey of Residual Risk***

***Preparatory to the Red Team Review on 3/28-31/00, we did a Survey of Residual Risk***
***Developmental activities were tracked through “community-based” databases***
***There are eight such databases:***
***Project-Level Reviews ***
***Spacecraft ***
***Flight Software ***
***Operations ***
***GSFC / NCR ***
***Materials / Processes ***
***Waivers ***
***Schedule Liens ***
***Vast majority (>90%) of all entries are in the first four databases, but since:***
***Flight Software entries generally mirror Spacecraft entries, and ***
***Operations database does not include flight hardware -- therefore***
***Only the Project-level reviews and the Spacecraft databases were surveyed for residual risk in preparation of the initial Red Team Review***

## Initial Survey of Residual Risk (continued)

***Initial Survey of Residual Risk ****(continued)*

***All of the RFAs were reviewed and 82 were selected to have potential residual risk***
***All of the PRs after starting with the first Thermal/Vacuum test were reviewed and classified***
***Any change to flight hardware***
***Any change to flight software***
***Any Redbook candidate***
***Any operational constraint***
***Any open item affecting flight hardware / software***
***Any significant test anomaly occurring during I&T was also selected as a “Special Topic” (57)***
***These 263 residual risk candidates were reviewed and accepted by the GSFC Systems Safety and Mission Assurance Office on 3/17/00***
***All of these residual risk candidates were addressed in the Red Team Review with the mission elements wherein they reside***
***Red Team concerns were almost entirely restricted to the “Special Topics”***

***All of these were selected (124)***

## Initial Red Team Recommendations (5/9/00)

***Initial Red Team Recommendations ****(5/9/00)*

***Spacecraft is a single-string design***
***Risk Mitigation:***
*Obtain at least 300 hours of failure-free operation on the entire spacecraft **[Estimate 289+]*
*Implement the Accelerated Minimal Mission **[DONE]*
***WARP is required for the Minimal Mission***
***Risk Mitigation:***
*Obtain at least 300 hours of failure-free operation **[ESTIMATE 700]*
*Perform WARP Parts Stress Analysis **[DONE]*
*Design a WARP Back-Up **[DONE]*
***Flight Software still undergoing change with minimal failure-free hours***
***Risk Mitigation:***
*Conduct “walk-throughs” of all critical flight and ground S/W **[DONE]*
*Freeze FSW **[DONE]*
*Exercise this FSW in T/V testing **[DONE]*
***High-Fidelity hardware / software test bed does not exist:***
***Risk Mitigation:***
*Supplement FSW Maintenance Facility **[DONE]*

## Initial Red Team Recommendations (continued)

***Initial Red Team Recommendations ****(continued)*

***QA process applied to GSFC GFE inconsistently:***
***Risk Mitigation:***
*Maximize failure-free operating time **[DONE]*
*Implement Accelerated Minimal Mission **[DONE]*
***Helium adsorption on HRGs:***
***Risk Mitigation:***
*Do a worst case analysis **[DONE]*
*Improved nitrogen purge **[DONE]*
***WARP, PSE, and ACDS had thermal cycling as opposed to thermal / vacuum testing:***
***Risk Mitigation:***
*Determine thermal stresses at maximum power levels **[DONE]*
*Evaluate performance in T/V testing **[DONE]*

***All initial Red Team Recommendations Accomplished !***

## Red Team Follow-Up Meeting

***Red Team Follow-Up Meeting***

***The Red Team Follow-Up Meeting on 6/13/00 involved the following:***
***Presentation and discussion of PRA, FMEA, and FTA***
***Review of earlier Red Team RFAs***
***PRA results:***
***Reliability of Minimal Mission @ 1 year is 0.75***
***Accelerating the Data Collection Events from four / day to eight / day allows the Minimal Mission to be largely completed in four months at a reliability of 0.90***
***Red Team strongly recommended the implementation of the Accelerated Minimal Mission to achieve the higher reliability***
***All RFAs from the initial Red Team Review were accepted ***
***Two new RFAs were added:***
***Factor the “1R” failures into the reliability calculations***
***Describe the single-point failures associated with the Safehold Mode***
***These RFAs have since been completed and accepted***

## Delta Pre-Ship Review

***Delta Pre-Ship Review***

***Delta Pre-Ship Review held on 8/8-9/00***
***Combination review:***
***Traditional Pre-Ship Review***
***Final Red Team Review***
***Single Board -- Co-Chaired by Charles Vanek and Ron Thomas***
***Three areas of potential risk identified:***
***S-Band Transponder***
***Launch Vehicle Fairing***
***Flight Software Independent Assessment***
***All three will be presented as Special Topics***
***21 RFAs assigned and have since been submitted***

## Flight Software Independent Assessment

***Flight Software Independent Assessment***

***Held at GSFC on 9/08/00***
***Two members of the IV&V Facility (West Virginia) visited GSFC:***
***Requested documentation was posted at a web site two weeks prior to the visit***
***No formal presentations during the visit***
***Team spent the morning asking questions***
***Later inspected software documentation and databases***
***Organized by Bill Jackson, IV&V Deputy Director***
***A different kind of review -- favorable impressions on both sides***
***Treated as a separate Special Topic ***
***No show-stoppers***
***Made eight risk mitigating recommendations that we have adopted***
***Final Report included in Probabilistic Risk Assessment document***

## Operations Readiness Review

***Operations Readiness Review***

***Operations Readiness Review (ORR) held on 10/3/00***
***Combination Review:***
***Traditional ORR -- chaired by ***
***Red Team represented by Ann Merwarth***
***Walk-on chart summarizing the outcome to be presented at the MRR***

## Special Topics

***Special Topics***

***1.******	******WARP Status***
***2.******	******S-Band Transponder***
***3.******	******Launch Vehicle Payload Fairing***
***4.******	******Hyperion Calibration Lamps***
***5.******	******Flight Software Independent Assessment***
***6.******	******Sprague Capacitors***

## Special Topic:

***Wideband Advance Recorder / Processor (WARP)***

## WARP Status (1 of 3)

***WARP Status ****(1 of 3)*

***Wideband Advanced Recorder / Processor (WARP) is a microprocessor-based 48 Gb solid state memory that ingests all imaging data from the three instruments at about 500 Mb/sec***
***It is essential for the Minimal Mission***
***A 10V regulator failed initially on 1/4/00 and again on 2/13/00 -- the problem was found to be a failed Zener voltage regulator***
***The failing part overstressed other parts so that the entire 10V regulator board was replaced***
***The WARP was re-assembled, re-verified, and returned to the S/C on 5/15/00***
***Re-verification consisted of:***
***Conducted susceptibility***
***Conducted emissions***
***3-axis vibration at workmanship levels***
***Four temperature cycles***
***Functional tests between each environmental test***
***Re-integration onto the Spacecraft was accomplished with no difficulty***

## WARP Status (2 of 3)

***WARP Status ****(2 of 3)*

***After re-integration there was a second spacecraft Thermal / Vacuum test (T/V II):***
***Three trips to +40°C for a total of 136 hours***
***Two trips to +5°C for a total of 135 hours***
***A complete CPT at +40°C and +5°C ***
***Four functional tests during T/V II***
***Over 100 DCEs transmitted***
***No difficulties encountered***
***Over 500 hours on the new regulator board with no problems***
***Now over 2500 hours and well over 400 DCEs on the rest of the WARP***
***Calculated reliability at one year is 0.90***
***WARP is ready to fly !***

## WARP Status (3 of 3)

***WARP Status ****(3 of 3)*

***After second WARP failure, it was decided to pursue a Back-Up Solid State Recorder (BSSR)***
***The BSSR is a reliable, independent, CCSDS-compatible single card solid state memory that fits into the WARP with its own separate power source***
***Team members include Litton, Orbital, and QSS***
***Work started in April 2000 and the CDR was held in July***
***The WARP performed very well in T/V II and work on the BSSR was discontinued on 9/30/00***
***A complete electrical design was completed for the BSSR***
***This design would raise the WARP reliability from 0.90 at one year to 0.97, but cost a nine month launch delay***

## Special Topic:

***S-Band Transponder***

## S-Band Transponder (1 of 6)

***S-Band Transponder ****(1 of 6)*

***During T/V II the S-Band Transponder developed “storms” on the AGC output***
***Once properly calibrated, the AGC output is an analog signal proportional to the signal strength in the receiver and is used for this purpose***
***Diagnostic tests isolated the problem to the S-Band transponder and it was removed and returned to the manufacturer where the problem was readily demonstrated (the root cause was not determined)***
***In the interest of time, the same transponder was removed from the Triana mission and sent to CONIC for further evaluation prior to EO-1 integration***
***This transponder experienced two brief AGC transients while in test of CONIC***
***To demonstrate that these were random events, this transponder was then exposed to 50 thermal cycles (-20°C ************  +65°C) in vacuum over a week***

## EO-1 S-Band Transponder Test Logic(2 of 6)

## Thermal Cycling of S-Band Transponder (3 of 6)

***Thermal Cycling of S-Band Transponder ****(3 of 6)*

## S-Band Transponder (4 of 6)

***S-Band Transponder ****(4 of 6)*

***The AGC was utterly stable and no other problems were encountered***
***EMI / EMC testing was successfully accomplished at an independent lab near CONIC***
***Re-integration onto the S/C was successfully accomplished***
***Successful tests:***
***RF Functional Test***
***One Complete CPT***
***Spacecraft Functional Test***
***Compatibility Test Van***
***Self-Compatibility scheduled for 10/3/00***
***This transponder has over 800 hours on it and has passed all of our tests***

## EO-1 Launch Site S-Band Integration (5 of 6)

***S-Band Integration***

****16***

****20***

****32***

****72***

****184***

****188***

****196***

**** Denotes cumulative hours on S-band following integration***

## EO-1 Launch Site Flow (6 of 6)

****208***

***The S-Band Transponder is ready to fly !***

## Special Topic:

***Launch Vehicle Payload Fairing***

## Launch Vehicle Payload Fairing (1 of 2)

***Launch Vehicle Payload Fairing ****(1 of 2)*

***Some small debris was seen on the video of the Globalstar-7 mission at the time of payload fairing separation***
***KSC ERB concluded on 3/3/00 that the actual debris was a lubricant called Fluoroglide***
***After examining the data, the EO-1 Project judged the contamination risk to be unacceptable***
***KSC ERB recommended on 6/19/00 not to fly the fairing “as-is”***
***In August, Boeing proposed a shield over part of the separation line***
***This approach was presented to the Delta Pre-Ship Review --  the Board, as well as the Project, was uncomfortable with this approach***
***Boeing agreed to disassemble the fairing, remove the Fluoroglide from the rail assembly, and re-assemble it using a traditional alcohol lubricant that leaves no residue***
***This approach has been successfully implemented***
***GSFC recommended tests confirmed the removal of the Fluoroglide***

## Launch Vehicle Payload Fairing (2 of 2)

***Launch Vehicle Payload Fairing ****(2 of 2)*

***The EO-1 fairing was also slightly damaged while in transit to Vandenburg Air Force Base (VAFB)***
***Damage was a delamination of about 5” x 7”***
***Such delaminations sometimes occur in fabrication and established procedures are available for their repair***
***Such a repair was successfully implemented***
***GSFC experts reviewed all of the KSC ERB documentation and are confident the repair is acceptable***
***Both issues with the payload fairing have been independently reviewed by GSFC experts and are no longer a concern to the Project***
***The residual risk associated with the fairing is acceptably low***
***HQ has requested that the Red Team review the resolution of these fairing issues***
***This Review is then a Launch Lien***

## Special Topic:

***Hyperion Calibration Lamps***

## Hyperion Cal Lamp Anomaly Background

***Hyperion Cal Lamp Anomaly Background***

***Hyperion response to primary cal lamp noticed to be degraded just prior to EO-1 T/V II; secondary lamp response normal***
***Additional tests performed during T/V II***
*Primary lamp response continued to degrade*
*Secondary lamp response remained stable after small increase in output*
***Investigation revealed that the cal lamps were changing output because they were not subjected to an adequate burn-in prior to installation***
***Tungsten-halogen lamps must be burned-in to stabilize the filament (that operates at 3000C) before use******.***
*Welch-Allyn recommends burn-in 1% of life = 6.5 hours minimum*
***Estimated cumulative on time for Hyperion lamps (as of 7/31/00):***
*Primary: **** 2.5 hours; Secondary: **** 1 hour*
***Additional Hyperion cal lamp burn-in performed on spacecraft after EO-1 shipment to VAFB***

## Hyperion Flight Cal Lamp Burn-in Results

## GSFC Extended Lamp Burn-In Results

## Maintenance of On-orbit Calibration

***Maintenance of On-orbit Calibration***

***Hyperion radiometric accuracy requirement is 6%***
***Case 1:  Secondary cal lamps continue operation during mission***
***Stability of secondary lamp output is +/- 0.25 %***
***Radiometric accuracy will remain 2.5 to 3 % ***
***Case 2: Secondary lamps last through several solar cals***
***Perform solar cal as early as possible on-orbit to calibrate lamp output***
***If secondary fails, increase solar calibration to daily event***
*Uses up one of the eight scheduled image collects per day*
*Potential degradation in white paint reflectance from frequent solar exposure*
***Radiometric accuracy will remain 2.5 to 3 % with lamps intact, degrades to 4 to 5% without lamps***
***Case 3:  Secondary lamps fail immediately, before solar cal***
***Rely on solar calibration, cross-instrument (ALI, AC) and cross-platform (Landsat) measurements of selected ground sites, solar and lunar calibration***
***Radiometric Accuracy will remain at 4 to 5%, still meeting the 6% requirement***

## Special Topic:

***EO-1 Flight Software Independent Assessment***

## Overview

***Overview***

***At the EO-1 Delta Pre-ship Review, Charles Vanek recommended an IV&V Independent Assessment (IA) of EO-1 Flight Software (FSW) to be completed before MRR***
***The IVV Facility in West Virginia provided two senior analysts for three weeks ***
***Project documentation was provided to IA team prior to a face-to-face meeting***
***Final Report delivered on 9/8/00***
***EO-1 accepted all of the recommendations***

## Assessment Scope

***Assessment Scope***

***Check status of program issues from previous reviews***
***Random test runs to demonstrate:***
***Command validation (accept valids / reject invalids)***
***Exception handling***
***FSW Patch uplink verification***
***Ops mode transitions***
***Review problem closures and verification techniques***
***TSM/RTS and FDC actions and relationship to FMEA***

## Review Materials Provided

***Review Materials Provided***

***Review Presentations (CDR, PSR, Red Team, and Delta PSR)***
***FMEA, FTA, and PRA documentation***
***Access to PTR, PR, and Work Order Databases***
***FSW design specs and data flow diagrams***
***Test procedures, setup, and condition descriptions***
***Test output, logs, and other reporting documentation***

## Findings

***Findings***

***No significant risks unresolved from previous reviews***
***FSW test practices and coverage of the testing adequate***
***Trending analysis demonstrates that FSW is mature and the development process is stable ***
***No issues identified against fault contingency processes or fault handling ***
***Eight procedural or documentation clean-up recommendations which are being completed by the Project***

## Recommendations

***Recommendations***

***Table upload procedures to include processor restart recovery check***
***Default memory scrub rate to be increased if dictated by SEU predictions***
***Central server for baseline program documentation to be implemented before launch***
***Traceability from FSW requirements to test cases to be documented before launch***
***Future Work Orders to be annotated to identify steps that address each PTR closure***
***Project to review and close remaining PTRs***
***Inaccurate comments in RTS database to be corrected***
***FDC table entries to be annotated with reference sources***

## Special Topic:

***Sprague Capacitors***

## Vishay Sprague Capacitor Issue

***Vishay Sprague Capacitor Issue***

***At GSFC, IRAC mission had a Vishay Sprague CWR09 part failure.  GSFC team went to Sprague to investigate the issue.***
***GSFC discovered that Sprague’s test procedures and test fixture problems have allowed an undetermined number of improperly screened capacitors to be delivered to several GSFC missions (IRAC, EO-1, MAP)***
***CWR09 capacitors from Sprague are suspect, if they were processed at the West Palm Beach facility.  Capacitors from Sprague’s Concord facility are not affected. ***
***Data from the origins of CWR09 lots is being gathered by EO-1 part engineers.***
***12 suspect capacitors are in the WARP box.***
***Engineers are currently evaluating the specific locations are these capacitors to understand the severity of this issue. ***
***CWR06 capacitors from Sprague also may be suspect. ***
***WARP, PSE and possibly ALI may contain these suspect capacitors.***
***Part Engineer's are evaluating the CWR09 parts first, then will investigate the CWR06 parts.***
***CWR06 parts are more numerous than the CWR09’s. ***

## Vishay Sprague Capacitor Issue

***Vishay Sprague Capacitor Issue***

***Successful testing of residual parts from same lot as flight is a way to mitigate change out if sufficient quantities exist, at least 100 per lot.  Small samples will not provide sufficient data.  EO-1 does not have sufficient residual parts to test, so this is not an option.***
***Date Code is not a factor.  All date codes for parts tested at West Palm Beach facility are suspect.***
***This issue emerged on 9/29/00 and is still being worked.***
***The resolution of this issue becomes a Launch Lien.***

## Vishay Sprague Capacitor Issue

***Vishay Sprague Capacitor Issue***

***At GSFC, IRAC mission had a Vishay Sprague CWR09 part failure.  GSFC team went to Sprague to investigate the issue.***
***GSFC suspects that Sprague’s test procedures and test fixture problems may have allowed an undetermined number of inadequately screened capacitors to be delivered to several GSFC missions (IRAC, EO-1, MAP)***
***CWR09 capacitors from Sprague are suspect, if they were processed at the West Palm Beach facility.  Capacitors from Sprague’s Concord facility are not affected. ***
***Data from the origins of CWR09 lots have been gathered by EO-1 part engineers.***
***Six suspect capacitors are in the WARP.***
***Engineers are currently evaluating the specific locations of these capacitors to understand the severity of this issue. ***

## Vishay Sprague Capacitor Issue

***Vishay Sprague Capacitor Issue***

***Successful testing of residual parts from same lot as flight is a way to mitigate change out if sufficient quantities exist, at least 100 per lot.  Small samples will not provide sufficient data.  EO-1 does not have sufficient residual parts to test, so this is not an option.***
***Date codes near to IRAC for parts tested at West Palm Beach facility are suspect.***
***This issue became known to EO-1 on 9/29/00 and is now being worked aggressively.***
***The resolution of this issue becomes a Launch Lien.***

## Current Status

***Current Status***

***Screening***
***Since the concern is potential early failures that escaped through faulty factory screening tests, these parts are somewhat less likely to be involved due to:***
*Successful completion of a 50A surge test, and*
*Over 2500 hours of use with no difficulties; not a part of LVPC re-build*
***Application***
***The six parts are in the WARP RSN***
***They are power filters across a 15V regulated supply***
***They are rated at 50 VDC -- derated >3 to 1***
***This is not a stressful application and promotes “self-healing” of the capacitor; current limited voltage source***
***Still defining the consequences of a failure***
***Resolution***
***All of the necessary data will be available next week***
***Codes 300, 400, and 500 will concur and provide an e-mail to the PMC Chairman***

## Redbook Candidates

***Redbook Candidates***

***The EO-1 Project proposes the following ten events as Redbook candidates:***
***In order of priority:***
***1.******	******Helium adsorption on HRGs***
***2.******	******Hyperion calibration lamps***
***3.******	******One-time, unrepeatable, unexplained events:***
*a.**	**Apparent X-Band RF frequency shift*
*b.**	**A/D anomalous maximum value*
*c.**	**Chassis current transient*
*d.**	**Sustained SADA chassis current event*
***The helium absorption is a small but real risk due to the significant release of helium from the Launch Vehicle in the event of a launch scrub -- we have done all that we can, but a small, finite risk remains***
***The rest are of minimally low risk***

## Redbook Candidate (1 of 7)

***Redbook Candidate ****(1 of 7)*

***Litton Space Inertial Reference Unit uses three Hemispherical Resonator Gyros (HRGs)***
***Atmospheric helium adsorbs on the quartz of the HRGs increasing their Parametric Drive Voltage (PDV)***
***Not a problem until Spacecraft arrived in Building 7 where helium is used in the environmental chamber testing processes***
***PDV initially about -1.0V and decreased to -2.80V within a month. HRGs fail to reliably start when below -5.0V***
***Nitrogen purge quickly installed and subsequently improved including continuous atmospheric monitoring***
***Primary helium source determined to be a vent near the Building 7 air intake -- since moved***
***This approach has been successful and implemented at the launch site for continuous purging while at VAFB and on the launch stand***
***PDV is slowly increasing and now stands at -2.6V***
***Our goal was to be above -4.0V throughout the launch campaign and we have met this goal***
***Remaining risk is the potential release of significant helium from the launch vehicle in the event of a launch scrub and our purge system fails outright***
***We are theoretically protected, but a small, finite risk remains in the event of a launch scrub***

## Directly prior to T/V II, the Hyperion primary calibration lamps were found to be degraded, but the secondary was normal
Investigation revealed that the calibration lamps were not adequately “burned-in”
During additional burn-in, a primary calibration lamp failed
Subsequent examination of 15 bulbs from the same lot revealed:
An anticipated life of 146 hours -- quite adequate for the mission
Halogen cycle not working well at ambient pressure
Halogen cycle working properly in vacuum
To change out the primary calibration lamps is a two-month launch delay
The secondary is stable and should last throughout the mission
These calibration lamps are transfer standards between solar calibrations
Operational workarounds have developed to compensate for the loss of the secondary calibration lamps and still maintain radiometric accuracy
This is a negligible risk --  See Special Topic for details

***Directly prior to T/V II, the Hyperion primary calibration lamps were found to be degraded, but the secondary was normal***
***Investigation revealed that the calibration lamps were not adequately “burned-in”***
***During additional burn-in, a primary calibration lamp failed***
***Subsequent examination of 15 bulbs from the same lot revealed:***
***An anticipated life of 146 hours -- quite adequate for the mission***
***Halogen cycle not working well at ambient pressure***
***Halogen cycle working properly in vacuum***
***To change out the primary calibration lamps is a two-month launch delay***
***The secondary is stable and should last throughout the mission***
***These calibration lamps are transfer standards between solar calibrations***
***Operational workarounds have developed to compensate for the loss of the secondary calibration lamps and still maintain radiometric accuracy***
***This is a negligible risk --  See Special Topic for details***

***Redbook Candidate ****(2 of 7)*

## Redbook Candidate (3 of 7)

***Redbook Candidate ****(3 of 7)*

***After Spacecraft vibration on 8/4/99, the first attempt to use the X-Band downlink resulted in failure to achieve carrier lock***
***Test personnel saw an apparent frequency shift of 6-7 MHz on spectrum analyzer***
***The next day, more equipment was brought in to examine the problem, but it disappeared and never occurred again***
***Detailed examination failed to find the cause of the problem so a panel of independent experts was convened by the Deputy Center Director***
***FTA performed and individual branches systematically ruled out***
***Experts’ Findings:***
***Flight hardware essentially ruled out as probable cause***
***Most likely cause was RF GSE cables that were damaged in handling / use***
***Damaged cables display selective frequency attenuation (SFA) that leads to loss of carrier lock and an apparent frequency shift***
***These cables were replaced by the Project early in its investigation***

## Redbook Candidate (4 of 7)

***Redbook Candidate ****(4 of 7)*

***Some of these RF GSE cables were subsequently found and tested -- they displayed SFA***
***David Israel (Code 527) was able to successfully model an apparent frequency shift based on SFA for comparable cables***
***X-Band System now has over 700 hours on it since this one-time incident and has successfully downlinked well over 300 DCEs***
***Although never specifically reproduced, there is strong circumstantial evidence to believe that RF GSE cables were responsible for this one-time event***
***This concern is of negligible risk to the mission***

## Redbook Candidate (5 of 7)

***Redbook Candidate ****(5 of 7)*

***PR-837-20-1: While loading software in the housekeeping RSN, the A/D in the PSE RSN indicated that the PSE LVPC total output current was “FF: or 19.275A for one sample while the Spacecraft was quiescent and no heaters were ON***
***Occurred only once in over 2500 hours (>9 x 10******6****** samples)***
***LVPC overcurrent trip did not occur***
***Umbilical telemetry (battery current, battery voltage, and chassis current) remained nominal***
***Fault tree analysis completed and each branch explored***
***No credible cause was identified:***
***No evidence of “FF” representing actual current***
***GSE found to be operating normally***
***A/D timing explored and found to be adequate, but marginal***
***Conclude this is a random event of unknown etiology***
***Judged to be a random event of low risk to the mission***

## Redbook Candidate (6 of 7)

***Redbook Candidate ****(6 of 7)*

***PR-770-20-3 describes a one-time transient of 300ma chassis current that occurred on the stripchart recorder on 11/22/99***
***The transient was less than one second in duration***
***The event was also seen in the telemetry***
***EMC testing was occurring at the time of the transient and various test probes were connected to the Spacecraft power bus***
***Investigation was unable to identify a probable cause***
***This transient was most likely associated with the GSE used in the EMC testing***
***As such, this one-time transient is of negligible risk to the mission***

## Redbook Candidate (7 of 7)

***Redbook Candidate ****(7 of 7)*

***PR-572-30-10 describes a prolonged chassis current of 925 ma on 8/20/99***
***Ad hoc testing following the event was able to reduce the problem by moving the Solar Array Simulator Cable (EGSE)***
***Inspection of this cable revealed split insulation on several wires in the backshell of the connector***
***A new Solar Array Simulator Cable was fabricated***
***In the succeeding 2500 hours of Spacecraft powered testing the problem has not recurred***
***Although we cannot be absolutely certain, there is strong presumptive evidence that the failed insulation in the EGSE cable was responsible for this event***
***This event is of negligible risk to the mission***

## Launch Liens

***Launch Liens***

***Successful completion of remaining planned work***
***Sprague capacitors in WARP LVPC (IRAC problem)***
***Conduct Red Team review of fairing issues***
***Complete closure of open paper***
***Completion of any RFAs from MRR***
***Presentation of MRR Overview to Office of Earth Science***