Two astronauts float out on to the International Space Station in first of three spacewalks to fix faulty cooling system pump

Nasa completes first of three spacewalks to fix ISS's faulty cooling system pump T wo American crew members named Rick Mastrachhio and Michael Hopkins made an urgent repair to the cooling system 'Potentially serious fault' saw half of station's system shut down last week If Mastracchio and Hopkins keep up the quick work, two spacewalks may be enough to complete the installation of a spare pump and a third spacewalk will not be needed on Christmas Day as originally anticipated Astronauts removed an old space station pump today, sailing through the first of a series of urgent repair spacewalks to revive a crippled cooling line. The two Americans on the crew, Rick Mastracchio and Michael Hopkins, successfully pulled out the ammonia pump with a bad valve -- well ahead of schedule. SCROLL DOWN FOR VIDEO The spacewalk by the two American astronauts on the International Space Station over the weekend went faster than planned and appeared to go off without a hitch Mission: One of the astronauts can be seen working on the broken pump If Mastracchio and Hopkins keep up the quick work, two spacewalks may be enough to complete the installation of a spare pump and a third spacewalk will not be needed on Christmas Day as originally anticipated. Pictured is Rick Mastracchio checking the spacesuits Rather than allow Mastracchio to wear that suit again, astronauts are planning to work on resizing a spare spacesuit aboard the ISS for him on his next spacewalk to complete the ammonia pump module replacement.