troubleshooting resulted in the unit starting up again, then immediately shutting down. The cause was eventually traced to gas bubbles in the unit, which remained non-functional until a Progress resupply mission in October 2004. In 2005 ISS personnel tapped into the oxygen supply of the recently arrived Progress resupply ship, when the Elektron unit failed. 2005 – Elektron oxygen generator fails again Early on January 1, 2005, the Elektron generator, repaired in 2004, failed again, and the crew had to rely again on onboard oxygen. 2006 – Venting of gas On 18 September 2006, the Expedition 13 crew activated a smoke alarm in the Russian segment of the International Space Station when fumes from one of the three Elektron oxygen generators triggered momentary fear about a possible fire. The crew initially reported a smell in the cabin. The alarm was later found to be caused by a leak of potassium hydroxide from an oxygen vent. The associated equipment was turned off, and officials said there was no fire and the crew was not in any danger. The station's ventilation system was shut down to prevent the possibility of spreading smoke or contaminants through the rest of the complex. A charcoal air filter was put in place to scrub the atmosphere of any lingering potassium hydroxide fumes. The space station's programme manager said the crew never donned gas masks, but as a precaution put on surgical gloves and masks to prevent contact with any contaminants. On 2 November 2006, the payload brought by the Russian Progress M-58 allowed the crew to repair the Elektron using spare parts. 2007 – Computer failure On 14 June 2007, during Expedition 15 and flight day 7 of STS-117's visit to ISS, a computer malfunction on the Russian segments at 06:30 UTC left the station without thrusters, oxygen generation, carbon dioxide scrubber, and other environmental control systems, causing the temperature on the station to rise. A successful restart of the computers resulted in a false fire alarm that woke the crew at 11:43 UTC. By 15 June, the primary Russian computers were back online, and communicating with the US side of the station by bypassing a circuit, but secondary systems remained offline. NASA reported that without the computer that controls the oxygen levels, the station had 56 days of oxygen available. By the afternoon of 16 June, ISS Program Manager Michael Suffredini confirmed that all six