Issues Resolved Since PSR

1. Issues Resolved Since PSR Lester Farwell OMPS Chief Engineer

2. Issues Since OMPS PSR Performance Issues (Compliance, etc) • MIL-STD-1540C PFM Compliance: CLOSED • Details for OMPS identified in SER (Systems Engineering Report) IN0092TST-074 • Residual risk: NONE – PFM testing compliant • ISS Cable Vibe: CLOSED • Questions regarding RV of flight cables with unit level testing • Residual risk: LOW (RFS=2) – Analysis coupled with SC level testing • 40 Safety Related Items: CLOSED • TIM provided clarifications: acceptable to all • SAR updated and submitted for approval • Residual risk: NONE – SAR complete • FSW Change from 3.4 to 3.5: CLOSED • V 3.4 Updates for EEPROM Refresh Capability • EDCM_Inhibit_Enabled changed for TLM • V 3.5 Resets EDCM bit to V 3.3 state • Residual risk: NONE – No impact to mission Significant Hardware Issues • EEPROM Reset Line and Function: OPEN • SBC EEPROMs (two) share common reset line: on-orbit operational concerns for memory volatility • Residual risk: Low (RFS=3) – Redundancy available / Refresh capability • GD SBC Solder Stress: OPEN • Component lead solder stress cracks on similar boards and part types as SBC • Questions on thermal stress analysis approaches and resulting outcome • Residual risk: LOW (RFS=2) – FS >2 (300 cycles) • Activated Flux Cored Solder: CLOSED • BATC MAB: incorrect solder used for processing hardware • Residual risk: NONE – No impact to OMPS • S-lead Component: CLOSED • Questions regarding use of low temperature solder on electrical parts • Determined acceptable • Residual risk: LOW (RFS=2) – Redundancy available

3. EEPROM Reset Line and Function: OPEN Problem Statement • SBC EEPROMs (two) share common reset line • Drain resistor 4.75 KOhms • Worst case (EV) reset voltage > Spec 0.8 V DPSR Risk Assessment • Current risk assessment: Moderate (RF=3) • Likelihood (Probability): • Remote: L = 1 (<10% chance) • Impact (Technically): • Moderate: I = 3 (degraded sys performance • Same part on-orbit: CALIPSO 2 years – NO Resets or problems • SBC redundancy available • EEPROM refresh capability Potential OMPS Impacts • Potential for on-orbit malfunctions during mode transitions of EEPROM reset voltages • Possible corruption of EEPROM memory • Could impact two simultaneously DPSR Status • Part characteristics critical: assessing • Plan to UAI Status: OPEN OMPS UAI Resolution Methodology • Investigate input leakage current • Present EOL value is 100 uA: Realistic?? • Estimates range from 2x smaller to 10x smaller in value • EOL calculations for WCA reset voltage dependent upon leakage value

4. GD SBC Solder Stress: OPEN Problem Statement • BATC FRB responding to GD alert for component stress from thermal cycling • Impacts two part types (inductor & IC – 1553 chip) • Component stress cracks on PWAs other than SBC • Same production line • Same part types and application process DPSR Risk Assessment • Current risk assessment: LOW (RF=2) • Likelihood (Probability): • Remote: L = 1 (<10% chance) • Impact (Technically): • Low: I = 2 (minimal sys degradation) Potential OMPS Impacts • Cause GD SBC incapable of proper operation, causing mission compromise DPSR Status • Results not expected to change: FS > 2 Resolution Methodology • GD performed additional accelerated thermal cycles to 300 over the range 140 oC DT • Stress marks developed after 24 thermal cycles • Stress cracks occurred after 93 thermal cycles • Stress cracks continued to degrade after 300 thermal cycles • No electrical failures were seen at 300 cycles. • BATC analysis for OMPS test and flight environments • Fatigue factor 4x in calculation • FS > 2 for OMPS expected application life • Additional analysis (BATC/GSFC) in progress: ~ 2 wks • Results not expected to change Status: OPEN OMPS SBC expected to be compliant

5. None Activated Flux Cored Solder: CLOSED Problem Statement • Solid flux-cored solder with activated rosin flux use for flight hardware within BATC • BATC Mission Assurance Bulletin MAB-2008-006 issued: • Notify assembly technicians of discrepant solder issue • Provide programs with a consistent approach to assess risk for affected hardware • Direct programs to review all solder spools for compliance and to identify all affected hardware DPSR Risk Assessment • Early cable risk factor assessment determined:3 (Likelihood = 1; Impact = 3-4) • Risk to TSP (TLM & signal) and co-axial cable lines (FPA clocks) • Current risk assessment: (after accelerated life test) NONE Potential OMPS Impacts • FPA’s – no impacts: cleaning and early fabrication • PWA’s – no impacts: cleaning and NVM measurements • Cables – Possible impacts: risk is possible corrosion at the solder locations of cable shield terminations only DPSR Status • NO cable degradation, corrosion, etc. Status: Closed No OMPS Impacts Resolution Methodology • Hardware testing – DOE by BATC MA & M&P • Testing completed for 10 year ground • NO corrosion, damage, or contamination • Root cause – determined • Discrepant solder removed from company • Corrective action for OMPS – None

6. S-lead Component Resolution: CLOSED Problem Statement • Micro circuit (UC1717) failed during MEB integration • Parts (8) are used on each Motor Driver Board for Cal Mech ops • Failed after PWA thermal cycling: +90 oC to -50 oC DPSR Risk Assessment • Current risk assessment: LOW (RF=2) • Likelihood (Probability): • Remote: L = 1 (<10% chance) • Impact (Technically): • Low: I = 2 (minimal sys degradation) Potential OMPS Impacts • Inability for Nadir and Limb to perform proper on-orbit calibration operations, compromising OMPS mission data DPSR Status • NO SPFs are mission limiting • NO Failures are propagating Status: Closed Minimal OMPS Impact Resolution Methodology • DPA of part indicated part was good internally • Fishbone diagram pointed to lead solder to part body • LCC using low temp solder • Soldered to PWB with low temp solder; then, reflowed • Part replaced; PWA, MEB, etc tested successfully • Functional (>1310 hrs – Pri, 600 hrs – Red, Failure free) • Environmental: RV, TVac, EMI • Reviewed solder application & process validation • Reliability analysis for part, functions, FMECA, SPF

7. None MIL-STD-1540C PFM Compliance: CLOSED Problem Statement • Determination of MIL-STD-1540C time & temp correctly • Determine final time vs hot dwell time against 200 hour measure • Determine complete PFM testing vs MIL-STD-1540C “Protoqualification” testing DPSR Risk Assessment • Current risk assessment: NONE Potential OMPS Impacts • Flight hardware not fully tested in environments • Insufficient environmental testing • PFM hardware lacks full environmental “qualification” DPSR Status • PFM testing compliant with tailored MIL-STD-1540C protoqualification requirements Status: Closed OMPS Compliant Resolution Methodology • Provide PFM test matrix vs MIL-STD-1540C “Protoqualification” testing • TIMs with NGST to assess final status of testing and completeness of documentation

8. ISS Cable Vibe: CLOSED Problem Statement • Questions regarding RV of flight cables with unit level testing DPSR Risk Assessment • Current risk assessment: LOW (RF=2) • Likelihood (Probability): • Remote: L = 1 (<10% chance) • Impact (Technically): • Low: I = 2 (minimal sys degradation) Potential OMPS Impacts • Flight hardware not fully tested in environments • Insufficient environmental testing • PFM hardware lacks full environmental “qualification” DPSR Status • LOW risk for testing of cables at NPP SC level Status: Closed OMPS Fully Compliant Resolution Methodology • Analysis to indicate relative loading vs connector interface location • Analysis indicates negligible impact to hardware performance; hence, mission success • Validation of impact demonstrated at NPP SC RV & acoustic testing

9. None 40 Safety Related Items: CLOSED Problem Statement • NASA/GSFC and IPO Safety Engineering provided various comments for closure to the OMPS SAR (Safety Analysis Report) DPSR Risk Assessment • Current risk assessment: NONE Potential OMPS Impacts • Delay OMPS shipment for non-approval of SAR DPSR Status • All comments addressed and closed Status: Closed OMPS Fully Compliant Resolution Methodology • Resolved all open items from GSFC Comments of NP-EMD.08.K121.098 • TIM held with NASA/IPO/NGST/BATC to address all final comments and closures

10. None FSW Change from 3.4 to 3.5: CLOSED Problem Statement • Limb straylight test (after PQ completion) performed • Full frame, single image contained LF pattern noise; not seen previously • FPA dark current not changed significantly DPSR Risk Assessment • Current risk assessment: NONE Potential OMPS Impacts • NONE to science • Additional 80 Hz noise negligible • Most images: EV with binning and co-addition • Problematic when viewing full frame images: 1 orbit/week DPSR Status • NO performance impacts: full ISS calibrated performance restored Status: Closed OMPS Fully Compliant Resolution Methodology • Performed investigation under flag for ISS configuration • Analysis & test configurations pointed to EDCM_INHIBIT_DISABLE bit as culprit • Change “0” to “1” for TLM dropouts (SW 3.3 – 3.4) • OMPS ERB decision to revert to “0” (SE 3.4 – 3.5)