Oxygen Supplies Tight on ISS
13 September 2004: NASA Space Station On-Orbit Status 13 September 2004
“Update on Elektron: The Elektron O2 generator is still Off. After the replacement of the gas analyzer for hydrogen (H2) in the O2 line by Padalka last Friday (9/10), the machine ran for about an hour and then shut down again. Moscow subsequently diagnosed the culprit to be a pressure increase in the hydrogen (H2) line due to cross-sectional constriction caused by deposits of KOH (potassium hydroxide) crystals.”
11 September 2004: NASA Space Station On-Orbit Status 11 September 2004
“Update on Elektron: The oxygen generator is still off. [Yesterday, CDR Padalka replaced the hydrogen (H2) gas analyzer at the O2 supply line and cleaned residue found when disassembling one of the filters. The unit was restarted, and it operated for about 5 min before shutting down due to bad readings from the newly installed gas analyzer.”
9 September 2004: Oxygen problems plague space station, MSNBC
9 September 2004: NASA Space Station On-Orbit Status 9 September 2004
“With the Elektron off, cabin pressure and ppO2 (oxygen partial pressure) have been decreasing by roughly 3.5 lb/day (= 2.5 mmHg/day). O2 margins without taking any actions are good for 10+ days. But cabin air total pressure will reach the lower limit of 14.2 psi (Flight Rule spec) around the morning of Saturday (9/11). Having accepted a slight drop below the limit, the ISS Mission Management Team (IMMT) will decide Monday (9/13) on the preferred source of the required repressurization.”
8 September 2004: NASA Space Station On-Orbit Status 8 September 2004
“Update on Elektron: The Russian oxygen (O2) generator is still off. [The crew performed limited troubleshooting this morning for the ground to acquire diagnostic telemetry. The problem this time is apparently not with bubbles in the BZh Fluid Unit but with the unit’s oxygen & hydrogen gas analyzer, which is a failure mode not seen before. With Elektron off, ISS will reach the lower O2 limit in the cabin air in 7 days. Beyond that, there is 62 lbs (28 kg) of O2 in Progress 15P, enough for 16 days. There are also 84 SFOG (solid-fuel oxygen generator) “candles” on board, which would supply another 42 days’ worth of O2. In short, total O2 margin is well above and beyond what is needed to make it to the next resupply date (Progress 16, on 11/26) and maintain redlines.]”
Reference: Service Module Atmosphere Revitalization Subsystem, Book 2, Mission Operations Directorate, 9 October 2000 [Acrobat] According to this document’s introduction “This book contains information for the crew about procedures and rules for the atmosphere revitalization subsystem, Elektron, Vozdukh, Micropurification Unit, and Fire Detection and Suppression Subsystem operations, as well as their schematic and operation logic.”
