This morning at 4am EST on the International Space Station, an Ammonia leak alarm went off, leading the crew to perform an emergency evacuation from the American capsule of the ISS. All of the astronauts are currently safe and secure in the Russian capsule of the ISS. The hatch between the two capsules has been sealed, and any non-essential equipment has been powered down.
Mission Control is in the process of assessing whether the alarm was the result of an actual leak or a malfunction, though recent reports from NASA TV suggest that the alarm was due to computer glitch and not a real leak. Currently the crew is still sectioned off in the Russian capsule, but are working to get systems in the US side up and running again.
Mission controllers at NASA’s Johnson Space Centre in Houston saw an increase in the station’s water loop pressure, and then an increase in cabin pressure, which in the worst case scenario is indicative of an ammonia leak. Ammonia leakage is not uncommon on the ISS. The last ammonia leak was in 2013, which required a spacewalk to repair.
Ammonia is used in the ISS as a coolant for the station’s large solar panels, keeping them as efficient as possible and preventing them from overheating. If the liquid Ammonia was leaking into the cabin, it would become a toxic gas which can be extremely harmful if the Astronauts were to inhale it. This is one of the three worst emergency scenarios for the ISS, the others being a fire, and a puncture due to a micrometeorite.
The evacuation comes just two days after the SpaceX Dragon capsule was captured by the ISS, containing supplies and experiments sent from Earth.