Mir Spacecraft Contamination Update
TO: Distribution
FROM: Team Leaders, LP/S Phase 1 Integrated Product Team (IPT)
SUBJECT: LP/S Phase 1 IPT Risk Mitigation and Flight Demonstration Experiments June 19 Board Minutes
The LP/S Phase 1 IPT Board met Wednesday, June 19, 1996, to review a proposed risk mitigation data analysis opportunity.
Mir-I Spacecraft Contamination Sources: Identifying and Reducing ISS Program Risks EM2/S.Koontz summarized the recent analysis of the brackets which supported the Docking Module camera (up on STS-74, returned on STS-76) for five months. Analysis suggests that the sides facing the Mir solar array controlling mechanisms were contaminated by leaks from the hydraulic control system. Outward facing bracket surfaces facing the Russian hardware turned brown. The inward surfaces remained white. The Alpha (absorption) changes from 0.2 to 0.5 (O is white; 1 is black). ISS allocated 30 Angstroms per year to station molecular deposition. Analysis of the camera brackets suggests 16 Angstroms permanent, non-reevaporating, deposition per day. Even larger silicone deposition rates are sugested by QCM data from: 1) DTO-829 QCM data taken during the sensor cooling period before Russian thruster firings (200 Angstroms per day), 2) Euro-Mir QCM sensor data (200 to 400 Angstroms per day, 3) Russian QCM sensor data ( 400 Angstroms per day). The available QCM data is probably worst case, does not include re-evaporation periods.
If Mir-1 is a reasonable example of ISS Russian segment contamination performance, then outgassing and deposition during ISS operations may be much higher than specifications allow. Contamination originating in Russian segment hardware, which is probably similar to the present Mir hardware, can reduce the ATCS radiator life to less than two years, the passive radiators to less that one year, and the photovoltaics to less than five years. The ISS program life requirement is fifteen years. The Board requested that Fred Kuo evaluate the proposed additional analysis and risks to Phase 2/3. The Board approved funding $31.3 K to obtain additional Mir data from T & M Engineering. Evaluation of Russian silicone usage and materials selections for FGB and service module is in progress.
signed
______________________________
OB/Tri X. Nguyen, NASA Team Leader
Leader
signed
______________________________
HS-40/Robert Gedies, Boeing Team
Leader
Encl. 1: Action Item
Ph1-146 Mir-I Spacecraft Contamination Sources: Identifying and Reducing
ISS Program Risks
Review the proposed analysis and confirm it will provide additional data
which contributes to the definition of the Mir contaminants.
Due: July 10, 1996
Action: OF/F.
Kuo
