“It has been decided that the foreign astronauts will spend the night in the Russian sector until the situation is resolved,” the source said.
NASA said it has no final confirmation that ammonia has leaked from an air conditioning unit in the US segment of the ISS.
“We have not yet received a final confirmation that a cooling agent has been leaked into the station’s atmosphere. So far we only have information from the cooling circuit that the pressure of ammonia has fallen,” the US space agency source said.
NASA also said that the pressure on the cooling unit has been blocked and the crew is checking the station’s atmosphere from a distance.
Earlier on Wednesday, NASA Mission Control in Houston said that an unplanned space walk may be necessary to fix the ammonia leak
Virts and Cristoforetti joined the ISS crew in November 2014, alongside Russia's Anton Shkaplerov, arriving at the station aboard a Soyuz TMA-15M spacecraft. Other members of Expedition 42 include NASA's Barry Wilmore and Russia's Elena Serova and Alexander Samokutyaev. The next expedition is expected to begin March 2015.