ISS Evacuated in Response to Gas Leak Scare
At approximately 4 am ET this morning, an alarm within the ISS indicated a possible leak of high-pressure ammonia gas. It now seems to be a false alarm, but the astronauts have been evacuated to the Russian section of the ISS pending confirmation that there is no danger posed by opening the hatches. Canadian astronaut Commander Chris Hadfield first alerted the public to the emergency situation:
Emergency on the Space Station. High pressure ammonia may be leaking inside. Crew closed hatches, safe for now in Russian segment. Analyzing— Chris Hadfield (@Cmdr_Hadfield) January 14, 2015
Hadfield went on to explain that ammonia gas is used to cool the station, and that a leak is one of the "big three" disasters that can befall the ISS. (Ammonia falls under the "toxin" category, while the other two are fire/smoke and decompression issues.) But he also stated that the crew is "calm, together, and working on the problem."
NASA went on to officially state that "no ammonia leak [has been] confirmed. Crew responded to coolant loop pressure increases." They also clarified that the alarms could have been set off by a pressure spike, which could indicate a gas leak, or by a faulty sensor or problem in the computer relay box. By 8 am, there seemed to be confirmation that it was a false alarm:
Update: #Exp42 crew informed by controllers that it's starting to look like a false indication, either a faulty sensor or computer relay.— NASA (@NASA) January 14, 2015
UPDATE 11:10 am: ISS manager Mike Suffredini gave a live update via NASA TV, in which he confirmed that all signs point to a false alarm. No ammonia was leaked and the crew is safe in the Russian sector. Some operations were shut down temporarily for the emergency procedures, but no research was lost because the freezers containing research samples were not turned off for more than eight hours.
UPDATE 4:45 pm: The astronauts are now back in the US side of the ISS. NASA is still maintaining that there was no ammonia leak, and that the alarm was likely set off by a computer glitch.