( CNN ) -- NASA scaled back operations on the International Space Station on Wednesday after discovering a problem with a cooling system . A pump on one of the station 's two external cooling loops shut down after hitting a temperature limit , NASA said . Teams worked to get the cooling loop back up and running , NASA said . Experts suspect a malfunctioning valve may have caused the problem , but they 're still trying to figure out how to fix it . The station and crew aboard were never in any danger , NASA said . Officials could determine that an emergency spacewalk is the best way to fix the failed pump -- something they 've done in the past . NASA said Thursday that there has been no decision on the spacewalk , and it may be a couple of days before the decision is made , according to Kenny Todd , the ISS mission management team chairman . The external cooling loops are systems that circulate ammonia outside the station to keep equipment cool . International Space Station Fast Facts . Officials discovered the malfunctioning loop was producing too much ammonia Wednesday morning , NASA spokesman Josh Byerly said . Teams have shut down some noncritical systems on the station as a result of the problem , NASA said . The space station 's life support system is still up and running . The current mission of the space station , officially called Expedition 38 , is scheduled to go until March 2014 . The six-person crew consists of NASA astronauts Mike Hopkins and Rick Mastracchio of the United States ; Russians Mikhail Tyurin , Sergey Ryazanskiy and Oleg Kotov ; and Koichi Wakata of Japan . CNN 's Drew Iden contributed to this report .
He said the space station and crew were never in any danger . A cooling pump shut down after hitting a pressure limit . An emergency spacewalk may be necessary , but it 's too soon to tell .