The Elektron oxygen generator aboard the international space station shut down New Year's Day and after three unsuccessful attempts to flush air bubbles from the device, the station astronauts were forced to tap into oxygen reserves aboard a Russian supply ship today, NASA officials said.

The International Space Station. Credit: NASA

Additional troubleshooting is expected, but it is not yet known what might be needed to clear air bubbles from the oxygen generator and return it to service. As of today, Expedition 10 commander Leroy Chiao and flight engineer Salizhan Sharipov had enough reserves for at least 57 days of normal operations, not counting additional oxygen in tanks attached to the U.S. Quest airlock module.

The reserves are in the form of so-called "candles," which produce oxygen as a by-product of combustion, and air brought up in the Progress 16P vehicle that docked to the station Christmas Day. Enough air for 15 days of operation is available in the Progress tanks while the candles can provide an additional 42 days of air.

The next Progress supply ship is scheduled to dock with the space station March 2, within a day or two of when the crew would need to tap into the Quest air supply if the Elektron cannot be fixed. The Progress will carry additional oxygen, as usual, and, depending on the results of additional Elektron troubleshooting, spare parts for the oxygen generator.

The Elektron suffered a similar malfunction in late August. The Expedition 9 crew was able to restore the unit to service after extensive troubleshooting and installation of an external pump assembly. Additional components, shipped up on a Progress, also were installed to complete the repair.

While the Expedition 10 crew is not in any immediate danger or threat of evacuation, this issue bears watching in the days and weeks ahead.