The crew of the International Space Station (ISS) have been forced to evacuate the American segment of the orbital outpost following an ammonia leak alarm.
The astronauts, who at the time were unloading supplies from the recently arrived Dragon capsule, were ordered to leave the segment and close themselves inside the Russian section after an increase of pressure in a coolant loop of the station’s cooling system was detected.
Earlier today Nasa said no firm data had so far been obtained that would confirm there had been an actual ammonia leak, although the increase in the pressure could be indicative of such an accident.
The evacuation, Nasa said, was carried out following emergency procedures as a precaution.
In a TV briefing, the agency said engineers at Nasa’s ISS control centre in Houston as well as their European and Japanese colleagues wereevaluating available data to find out what triggered the alarm.
Nasa said on Twitter the alarm may likely had been merely a reaction to a pressure spike, a faulty sensor or a problem in a computer relay box. Further information will be released later in the day.
There are currently six astronauts residing in the £100bn orbital research complex – Americans Bill Wilmore and Terry Virts, Russians Elena Serova, Alexander Samoukutyaev and Anton Shkaplerov, and Italian Samantha Cristoforetti.
Nasa said the astronauts’ schedule for today must have been scrapped.
Ammonia is used in pipes and heat exchangers on the outside of the station. “If it breaks through inside it is 1 of the big 3,” said former Canadian astronaut Chris Hadfield on Twitter.
The gas, characterised by its distinctive smell, is known to be highly toxic.