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ECLSS Assessment of Mir Hardware Systems

By Keith Cowing
NASA Watch
March 21, 1997
Filed under

From: Rotter, Hank A
Sent: Friday, March 21, 1997 9:55 AM
To: Sandars, George W.; Miller, C. Rick
Cc: Winkler, Eugene; Hoy, Mike; Brasseaux, Hubert J Jr.
Subject: FW: Mir Status Concern
ECLSS assessment of Mir hardware systems.
The Mir ECLSS systems are primary located in the Base (Core) Module and the Kvant Module. Active Thermal Control Core has two thermal control loops 1 is operating currently at reduced internal pressure. Radiator loop for heat rejection has lost auto control – manual control is being use and is acceptable for long periods (hours-weeks) at same attitude 2 is non operating has tubing leaks near pump package – plan to replace leaking tubing, when repair is plan-unknown. Radiator auto control still working with manual backup Kvant has one thermal control loop. Radiator flow lost. Loop has been connect to operating Core loop. Can be connect to either Core loop. Overall performance is slightly reduced.
Concern – leaks and flow problems indicates long-term corrosion problems that may quickly attack new replacements?? System health is marginal with long term problems. Performance marginal which drives desirable attitudes during periods of high Beta sun angles. Any additional failures could cause Mir to be abandon if fix cannot be implemented within a few days/hours.

O2 Control Has two water electrolysis system with three perchlorate O2 canisters. Electrolysis systems have problems with separation membranes?? We believe the membranes have deteriorated and do not prevent H2 from the O2 gas side. The system sensor continues to work and shut down unit when H2 on O2 side reach 2%. This occurs within an hour after actuation and then requires a N2 purge to remove the H2 which takes another hour and this becomes very crew intensive. Two of three perchlorate O2 canisters are damage and not usable, one was damage when the air flow was not activated and unit overheated; second destroyed by fire when O2 cartridge burn to fast and hot (March 97 Mir fire). Only one canister remains functional and is in use with many O2 cartridges available. O2 for several man-days are available from O2 masks and EVA O2 tanks for emergencies. System is one failure away from ending Mir operation, but spare O2 systems replacement is planned. Drink water. Drink water system has Mir water tanks, condensate recover, and Shuttle water containers. All are operational. System health is good and water quantities are good.
Humidity control One of two humidity control system operational. Lost of Kvant radiator cause other system to be ineffective. Remaining operational system was design to control humidity for two crewmen and is marginal for three crewmen. System is adequate but controls on the high side of range with three crew on Mir. Cold module surfaces has condensate form.
ECLSS Assessment System is functional with no margins in some cases, but system is not critical. In worst failure crew would have near a day to planned to leave Mir. Getting another electrolysis system is a must for any long term stay commitment beyond STS-84. Thermal loops (only one loop operational currently) condition concern me the most since repairs will not fix corrosion problems and other critical systems depends on cooling. If loops fails, leaving the Mir would not be time critical, i.e. safe with time to plan exit.
Recommendations A new electrolysis system should be install on Mir for any long term stay after STS-84. Also recommend a backup canister for perchlorate O2 generation for more redundancy but this is not mandatory. The second Mir core coolant loop leak should be repaired to provide the cooling redundancy. Need to verify that the auto control of the CO2 mole sieve has been recovered.

NASA Watch founder, Explorers Club Fellow, ex-NASA, Away Teams, Journalist, Space & Astrobiology, Lapsed climber.