Six astronauts, from three countries, are conserving energy aboard the International Space Station following the failure of one of two cooling systems. The astronauts may have to perform a spacewalk to repair the broken system.

Oleg Kotov, Commander Nationality: Russia Age: 48 Spaceflight Experience: Kotov spent 196 days aboard the International Space State during his first spaceflights in 2007. He has performed two spacewalks, or extra-vehicle activities, lasting a total of 11 hours and 47 minutes.

Rick Masstrachio, Flight Engineer Nationality: USA Age: 53 Spaceflight Experience: This is Masstrachio's fourth mission to space. He previously conducted missions to the ISS in 2000, 2006 and 2010.

Koichi Wakata, Flight Engineer Nationality: Japan Age: 50 Spaceflight Experience: Wakata has completed three missions to space logging a total 159 days, 10 hours, and 46 minutes in space.

Mikhail Tyurin, Flight Engineer Nationality: Russia Age: 53 Spaceflight Experience: Tyurin has been to the ISS twice, in 2001 and 2006 for a total of 340 days in space. In that time he conducted five spacewalks.

Sergey Ryazanskiy, Flight Engineer Nationality: Russia Age: 39 Spaceflight Experience: This is Ryazanskiy's first mission to space.

Mike Hopkins, Flight Engineer Nationality: USA Age: 44 Spaceflight Experience: This is Hopkin's first mission to space.

Source: NASA