“At the moment there is no need for the crew to transfer to the Soyuz ‘life ship,’ the portholes between the American and Russian segments are hermetically sealed so there is no danger. So far there is no confirmed ammonia leak according to the cooling system circuit in the Node-2 module and there is no danger to the astronauts and cosmonauts,” Central Command told RIA Novosti.
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.
Russia’s space agency, Roscosmos, said earlier that ammonia from an air conditioning unit in the American segment of the International Space Station was discharged into the station’s atmosphere. The American segment on the ISS is currently isolated, the crew is safe and located in the Russian segment.
The current ISS Expedition 42 crew is comprised of NASA's expedition commander Barry Wilmore, Russian flight engineers Alexander Samokutyaev, Elena Serova, and Anton Shkaplerov, ESA's Samantha Cristoforetti and NASA's Terry Virts. The team is due to return to Earth March 2015.
The most recent ISS crew evacuation to a Soyuz capsule occurred on June 24, 2012 due to a space junk alert. A piece of space debris large enough to damage the ISS was identified when it was already too late to move the orbiting habitat, but safely passed within some 23 miles.
