ISS Crew Flees to Russian Module After Possible Leak Crew is safe, NASA says it acted for 'worst case scenario' By Newser Editors and Wire Services Posted Jan 14, 2015 7:20 AM CST Updated Jan 14, 2015 8:41 AM CST 31 comments Comments This May 23, 2011 photo released by NASA shows the International Space Station at an altitude of approximately 220 miles above the Earth, (AP Photo/NASA, Paolo Nespoli) (Newser) – A problem in the US segment of the International Space Station today prompted its six-person crew to quickly lock it up and move to a Russian module, but they aren't in danger, Russian and US officials said. Russia's space agency Roscosmos said in a statement that a "leak of harmful substances from the cooling system" prompted the crew to isolate the American module. It added that mission control experts in Moscow and Houston quickly and efficiently cooperated to ensure the crew's safety. While Roscosmos said there was a leak, NASA said in a statement broadcast on its online television station there was still "no concrete data that suggests that there was in fact an ammonia leak." "We saw an increase in water loop pressure, then later saw a cabin-pressure increase that could be indicative of an ammonia leak in the worst case scenario, so we protected for the worst case scenario and isolated the crew in the Russian segment of the space station while the teams are evaluating the situation," NASA spokesman Bob Jacobs said. The Tass news agency reported that just about one third of ammonia was left in the coolant system at the US module and the rest has leaked out. The space outpost is manned by NASA astronauts Barry Wilmore and Terry Virts, Russians Elena Serova, Alexander Samoukutyaev and Anton Shkaplerov and European Space Agency astronaut Samantha Cristoforetti.