UPDATE: Nasa has released the following statement:
Earlier today, the pump module on one of the space station’s two external cooling loops automatically shut down when it reached pre-set temperature limits. These loops circulate ammonia outside the station to keep both internal and external equipment cool. The flight control teams worked to get the cooling loop back up and running, and they suspect a flow control valve actually inside the pump itself might not be functioning correctly. At no time was the crew or the station itself in any danger, but the ground teams did work to move certain electrical systems over to the second loop. Some non-critical systems have been powered down inside the Harmony node, the Kibo laboratory and the Columbus laboratory while the teams work to figure out what caused the valve to not function correctly and how to fix it. The crew is safe and preparing to begin a normal sleep shift while experts on the ground collect more data and consider what troubleshooting activities may be necessary.
An emergency situation was reported on board the International Space Station (ISS) after a cooling system failed. The news was first reported by NBC around 10.50pm (GMT). According to Nasa, the astronauts are not currently in danger.
A spacewalk may be required to fix the problem.
Speaking to Mashable, a Nasa spokesperson confirmed that the cooling system pump had shut down due to low temperatures.
They said: "The teams want to understand the system performance before activating the system. A flow control valve is not operating as anticipated. The teams are trying to understand what they are seeing.. The team may power off selected components to avoid over heating while they watch the flow control valve and temperature control capability."
NASA spokesman Josh Byerly told NBC, "The crew was never in any danger. They worked to keep the freezers going... They're fine for the near future."