14 DAY TRIAL // US astronauts Christopher Cassidy and Tom Marshburn aboard the ISS are doing a spacewalk to fix a cooling system pump which has been causing problems for the past few days.
Astronauts and ground control noticed an ammonia leak from the cooling system for the solar array panels.
The two astronauts are out fixing the problem, you can watch them work live thanks to a NASA stream.
The astronauts have already been out for a few hours, they've already replaced the faulty pump with a spare one.
The pump has already been turned on, so far there are no signs of any leakage. The astronauts will wait until the ISS comes from behind the Earth to try to get a better view with the sun out.
Even if everything goes well, the astronauts will then spend at least 45 minutes more, inspecting to see whether any ammonia ice has stuck to one of the space suits and then to wait for any ammonia that they may have missed to evaporate.
NASA Is live streaming everything here, there's a video feed on Ustream as well.