One of two cooling pumps on the International Space Station shut itself down after sensors detected a temperature anomaly, but the situation poses no threat to the six crewmembers, NASA said.

Engineers on the ground think the problem may lie with a flow control valve on the pump, which circulates ammonia coolant on the outside of the ISS, according to a NASA statement.

The next step is determining whether the fault can be corrected with a software fix. If not, crewmembers may have to go outside the ISS to replace the unit.

The pump problem forced a shutdown of non-critical systems aboard the ISS, which is currently carrying two U.S. astronauts, three Russian cosmonauts and a Japanese astronaut.

"At no time was the crew or the station itself in any danger," NASA said.

The ISS turned 15 last month and the partners in the venture - including NASA, Roscosmos and the European Space Agency - have agreed the station will remain operational until 2020.

Made up of 11 modules, the ISS has been continuously occupied since 2009. EFE