The crew of the International Space Station was forced to activate back-up oxygen generating equipment on Wednesday after the ISS’s main supply system broke down.
Russian engineers are struggling to repair the main “Elektron” oxygen supply system, which is located in the Russian Zvezda living module. The system converts water into hydrogen and oxygen.
But both Russian and US officials say the crew is in no danger. Secondary oxygen supplies should last for at least 100 days and a shuttle mission is scheduled to bring fresh supplies to the station in early June.
The back-up oxygen-generating process involves activating a chemical reaction in solid fuel canisters, known as “candles”. The crew is using these to maintain proper oxygen levels within the ISS modules.
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“They have the candles and everything is fine,” a NASA spokeswoman told New Scientist. “They are working with Russian mission control to solve the trouble.”
Pump problem
Each crew member uses one candle’s worth of oxygen per day and there are enough candles to last for 50 days. Another 50 days of oxygen is located in tanks attached to the outside of the US airlock. This is usually used to supply spacewalking astronauts but could be routed into the station itself.
The Russian oxygen generating system has been working intermittently in recent weeks. A NASA spokesman says a liquid pump on the Elektron unit appears to have failed.
This may be due to a fault with the pump itself or with a sensor controlling it. A replacement part may therefore be required or new software could be uploaded to solve the sensor problem.
A key part of the ISS mission is to maintain a permanent human presence in space. The current crew consists of Russian commander Yury Onufrienko and US flight engineers Carl Walz and Dan Bursch. The crew has been at the ISS since December 2001 and is scheduled to depart in June.
