THEMIS PROBE MISSION PRESHIP REVIEW Reaction Control System

THEMIS PROBE MISSION PRE-SHIP REVIEW Reaction Control System Michael Sholl University of California – Berkeley RCS Engineer MPSR Reaction Control System 1 UCB, 26 October 2006

Overview Major milestones: • Pressure test/leak checks performed successfully on all five probes at UCB prior to environmental testing • Environmental testing performed at JPL • Preship Review • Pressure test/leak checks will be repeated at Astrotech, per EWR 127. 1 guidelines (December 2006) • Fueling operations in early January 2007 MPSR Reaction Control System 2 UCB, 26 October 2006

RCS Issues/Status • F 1 PT 2 Pressure transducer: • • Latch valve indicator: Line underproof • • High pressure section: • Thruster/latch valve BPR manifold: CLOSED STEREO leak fallout: • CLOSED Vacco/Aerojet probed valves for contaminants: CLOSED Particulates contamination, Valvetech valves: CLOSED • Information on all issues available in backup slides • • MPSR Waiver sought for SV 2&3: Reaction Control System 3 UCB, 26 October 2006

Test Sequence Summary • Probe F 2 (pathfinder probe): ATP performed at Swales, no MEOP Leak check/MEOP repeated at UCB (pre-env. ) Pressurize to 100 psig, test, depressurize (JPL) Post-environmental Leak check/MEOP at UCB Final leak check/MEOP to be performed at ASO • Probes F 1, F 3, F 4, F 5 ATP performed at UCB, MEOP/Leak/Phasing Pressurize to 100 psig, test, depressurize (JPL) Final leak check/MEOP to be performed at ASO • All RCS systems are well within requirements, and ready to proceed to ASO for final checkout/fueling MPSR Reaction Control System 4 UCB, 26 October 2006

Test Sequence High Pressure Transducer / Pressurant Tank MEOP Test • High Pressure Transducer Output Test • (pressurize COPV to 1925 psig) • Pressurant Tank MEOP Test High Pressure Service Valve Functional Test • High Pressure Service Valve Leak Test • (depressurize COPV to flight level) SV 1 Manifold Tests • Isolation Valve Cycle Test • (SV 1 manifold to 400 psig) • Forward Leakage Test (decay/lockup test) using high-accuracy gauge • SV 1 Leakage Test using pipette • (depressurize SV 1 manifold)) Cycling tests on latch and thruster valves • LV Cycle Test • Thruster Valve Cycle Test Low Pressure Transducer / Propellant Tank MEOP Test • Low Pressure Transducer Output Test • (pressurize tanks to 400 psig) • Propellant tank MEOP Test Latch, thruster and SV 2 & SV 3 leak tests • Latch Valve Forward Leak Test • Thruster Valve Forward Leak Test • Low Pressure Service Valves (SV 2 & SV 3) Leak Test and AN cap leak test • (depressurize tanks to 42 psia) MPSR Reaction Control System 5 UCB, 26 October 2006

GSE • • 2 TE 35610 -301 (Low Pressure Test Panel) TE 35610 -301 (High Pressure Test Panel) Thruster enable test set Pipettes (1 ml) for valve leak checks Nozzle throat plugs and Tygon tubing Helium K-bottle Blast Shield • MPSR Supplied by ASO Reaction Control System 6 UCB, 26 October 2006

Fueling Operations • KSC fueling group managing fueling operations • • 49 kg +0. 5 -0. 0 requirement, each probe Ullage pressure adjusted for 400 psi MEOP at 40ºC Boeing/KSC GSE and fueling hardware used Worked extensively with UCB/Swales to tailor procedures for THEMIS – E 5534 G (THEMIS specific deviations) Preps. For Fuel Loading – E 5502 G (THEMIS specific deviations) Fuel Loading Procedure • • MPSR UCB signature required for changes to deviation cover sheet Fueling manifold fabricated, water loading practice run in September, 2006 Reaction Control System 7 UCB, 26 October 2006

Fueling Operations • • Three UCB personnel certified for SCAPE operation 24 hours after fueling, the fill/drain valves will be checked for hydrazine leakage Closeout for flight (AN cap installation, lockwiring) Defueling tools fabricated • • MPSR Pathfinder completed, video showing tool usage available. Controlled by E 5535 with case-specific inputs from THEMIS deviation template. Reaction Control System 8 UCB, 26 October 2006

Repressurization Limits • Thruster qualification levels • • Component qual. limits drive fuel load and repressurization Thrusters qualified from 85 -450 psia – No pulse data available above 400 psia – Steady 100 s pulse data at 450 psia MPSR • • THEMIS thrusters qualified down to 85 psia THEMIS thrusters tested to 50 psia • Key point: Repressurization between 85 and 400 psia limits possible without offloading propellant • 75 psia-425 psia limits would increase recharge window and operational flexibility by 29% Reaction Control System 9 UCB, 26 October 2006

Safety/MA Considerations • • MPSR 1. 5 x MEOP proof test low pressure panel 1. 1 x 1. 5 x. MEOP proof test for high pressure panel and lines Only required personnel in test facility Blast shield and PPE (face shield/goggles) in use O 2 alarm and placards in place Safety signoff at beginning and end of all haz. proc. MSPSP and Hazard Reports approved for CCAFS Range signoff Reaction Control System 10 UCB, 26 October 2006

Summary • • • MEOP/leak check/pressure transducer calibration performed on probes 1 -5 prior to environmental testing. All RCS systems completed environmental testing. MEOP tests will be repeated at Astrotech, per EWR 127. 1 guidelines, with several additional steps. Fueling Procedures Understood, GSE complete. RCS Issues/concerns thoroughly investigated and are considered closed. RCS system ready to ship to ASO! MPSR Reaction Control System 11 UCB, 26 October 2006

Backup Slides MPSR Reaction Control System 12 UCB, 26 October 2006

F 1 HP Transducer PT 2 pressure transducer (212790) on F 1 was reworked, due to thermal instability of conditioning circuit. New strain gauge installed, passed ATP in December, 2004. Installed on F 1 in April of 2005, ATP performed Shipped to Swales, July 2005, pressure transducer failed. Was removed by Aerojet, followed by extensive investigation. Machining chip from rework implicated, processes reviewed, 212790 rebuilt. Full ATP performed, burn-in performed at probe level subsequent to installation Installed on P 1, January 2006 X-ray inspection of weld joint Dye penetrant proof test (2625 psig on 11 January 2006) Rework caused problem on F 1. Because no rework was performed on probes F 2 -5, No problems are expected. To date, no further issues with Probe 1, PT 2. Issue closed. MPSR Reaction Control System 13 UCB, 26 October 2006

Latch Valve Anomaly • Valve. Tech Latch Valve heritage had a single Reed-Type CLOSED Position Switch • THEMIS requested that a second switch be added for redundancy (OPEN Switch) • Initial flight acceptance testing of several units was successful and those units were delivered and installed on RCS Probes 1 & 2 Subsequent units failed to indicate proper valve position following vibration testing • Closed valve appeared to have opened during random vibration based on switch indications • Valve was cycled & both switches read properly Other valves displayed similar anomalies • Switches on some valves indicated ambiguous readings and others were consistent but incorrect • One valve installed on RCS Probe 3 indicated ambiguously after rotating the RCS MPSR Reaction Control System 14 UCB, 26 October 2006

Failure Investigation/rework • After extensive failure investigation, problem determined to be improper switch locations (the internal physical position of each switch with respect to the pendulum with the magnet attached). • RCS Probes 4 & 5 switches were tested and adjusted as required • Reworked units passed acceptance testing • Valves previously installed in RCS Probes 1 and 2 never indicated problems and are assumed acceptable; no rework was done or feasible on switches in RCS Probe 3 MPSR Reaction Control System 15 UCB, 26 October 2006

Risk Buydown • No latch valve actually changed position • Some switches indicated a change in position • Other switches indicated ambiguous data • Switch anomalies only occurred after some dynamic response (random vibration) or after a physical movement such as a sharp bump or rotation. • The “mis-position of the switch” does not affect RCS on-orbit operation. For example, if the CDHS reads switch “Open, ” that will not prevent sending a command to “Open” the valve. • Once the Spacecraft is loaded and pressurized at KSC, a switch anomaly implies (without the ability to rule out) the loss of one mechanical seat, giving the appearance of a safety concern Procedures call for a CLOSE command be sent to reinforce the actual valve position in the event a switch anomaly occurs with a loaded RCS. This approach presented to GSFC on 27 January 2006, and our approach accepted. MPSR Reaction Control System 16 UCB, 26 October 2006

RCS Line Underproof • During Aerojet preship data reviews, two underproof conditions were discovered • • Welds on Pyro/Filter/SV 3 manifold (1500/2625) Line and orifice between latch valve and thrusters (900/1125 psig) MPSR Reaction Control System 17 UCB, 26 October 2006

System Underproofs Welds Underproofed BPR manifold MPSR Reaction Control System 18 UCB, 26 October 2006

HP Investigation • • • Documented in Swales TM 2080 -Underproof Summary (M. Leeds) By the time this was discovered, RCSs already installed in probes re-proof would have been risky HP lines • • • All Components tested to required levels (EIDP) Lines burst requirement is 15, 000 psig Remaining question was on integrity of welds – – • • MPSR Aerojet performed burst tests on 304 SS lines left over from flight build 20 line segments welded into pairs, using same welder All burst at pressures greater than 24, 000 psia Documented in 2006 -R-2747, System Under-Proof Pressure Test at SV 1 Discrepancy Report, Aerojet, 20 January 2006 Swales TM 2080 states that the RCS is ready for flight Investigation summary accepted by GSFC Safety, and CCAFS range safety (MSPSP/HR signoff) Reaction Control System 19 UCB, 26 October 2006

Latch Valve-thruster BPR underproof Investigation • • • Documented in Swales TM 2080 -Underproof Summary (M. Leeds) By the time this was discovered, RCSs already installed in probes re-proof would have been impossible, due to MEOP limits on tank and latch valve back-pressure-relief (BPR) Section should have been proofed to 1125 psig • • • MPSR Latch valves and thruster valves proofed to 1, 500 psig Orifice 600 psig (simply a small disc with a drilled hole, welded into the lines) Lines 900 psig Aerojet line burst tests show that these lines/welds burst at 24, 000 psi. Swales TM 2080 states that the RCS is ready for flight Investigation summary accepted by GSFC Safety, and CCAFS range safety (MSPSP/HR signoff) Reaction Control System 20 UCB, 26 October 2006

Response to STEREO Fuel Spill • STEREO Observatory A fueled on July 13, 2006 • During propellant fill, a small leak was noticed through the SV, and fueling stopped • Valve manufactured by Vacco Industries, S. El Monte, CA • Valve part number V 1 E 10572 -01, identical to THEMIS valves MPSR Reaction Control System 21 UCB, 26 October 2006

Response to STEREO Fuel Spill • STEREO valved leaked when: • • Valve fully opened (to stop) Side load present • STEREO valve did not leak when: • • Valve ¼ turn open Side load removed • THEMIS plan • • • MPSR Valve 1 -1 ¼ turns open per Aerojet instructions (not to stop) Small side load due to fueling manifold Additional leak checks (during MEOP and 24 hrs after fueling) Reaction Control System 22 UCB, 26 October 2006

Waiver for SV 2&3 • Valves have significant heritage (278 have flown) • Valves have two inhibits (valve seat and AN cap) • No provision exists for an external cap on this valve design • On THEMIS, and all future GSFC programs, any leakage of hydrazine is categorized as a catastrophic hazard, per EWR 127. 1 • Due to this hazard categorization, a waiver was requested • Waiver generated and submitted for signature • • MPSR Additional leak checks on AN caps prior to propellant loading Additional post-fueling valve seat leakage checks Reaction Control System 23 UCB, 26 October 2006

Valvetech Particulates Aerojet experienced leakage on 3 thruster valves during ATP hot fire on 0. 2 lbf thrusters (1 lbf thrusters on THEMIS) • Failed valves belong to one lot on another Aerojet program Mitigating Factors for THEMIS Mission Success • THEMIS REA valves manufactured in year prior to anomaly event – • • THEMIS REA valves passed ATP vibration, hot fire, and valve functionals THEMIS REA valves exposed to additional vibration regimes – – – • • Subsequent valves on other programs show no leakage 1) – Transportation vibe when shipped from Seattle to Beltsville, MD 2) – Transportation vibe when shipped from Beltsville, MD to JPL 3) – Probe level random vibe test at JPL THEMIS REA valves subsequently passed proof and leak at JPL Failures localized to suspect lot Investigation results provide confidence that THEMIS valves are not affected, and acceptable for flight MPSR Reaction Control System 24 UCB, 26 October 2006