Two astronauts who carried out an eight-hour spacewalk to repair a cooling system on the International Space Station, have been only partially successful.
The pair removed the unit's hoses but could not replace the bulky item as scheduled, the BBC reports.
The faulty unit is one of two that cool the station's systems, meaning the one functioning system is having to carry whole load.
Two walks had been planned to complete the work but NASA says a third will now be needed.
The space station has to cope with temperatures that can range from 121 degrees celsius to minus 157 degrees.
NASA says the three Russian cosmonauts and three NASA astronauts aboard the station are not at any risk, and if the second unit was to fail, the crew could move to the Russian segment of the Space Station, which has its own cooling system.
