The 15-year-old International Space Station suffered a cooling system failure on Wednesday, but NASA officials insist, for now, the crew is safe, and "there are no major concerns."

The cooling system pump shut down in response to low temperatures around mid-day Wednesday, NASA public affairs officer Joshua Byerly told Mashable. Crews are investigating the cause of the low temperature, however they think it's likely the result of the radiator, which was at -75 degrees.

Because the cooling system is outside the ISS, Byerly said a spacewalk may eventually be needed to fix the problem, and there is a contingency plan in place. "But we're not at the point where they would need that yet," he said.

The space station is constructed into two loops, each of which has its own cooling system pump. The failure occurred in loop A, so crews were forced to move operations to loop B. Byerly said there is nothing wrong with the pump itself, but rather a valve.

"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," he said. "The team may power off selected components to avoid overheating while they watch the flow control valve and temperature control capability."

In the meantime, crews powered down some non-essential operations in loop B, which includes the Japanese and European laboratories and the Harmony node, in order to maintain heat loads and conserve energy. UPDATE: Dec. 11, 6:47 p.m. ET: NASA issued its final statement on the ISS cooling system failure:

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.

Image: NASA