Last spacewalk of NASA's Atlantis astronauts

A pair of spacewalking astronauts floated outside the International Space Station to pack up a broken cooling pump and tackle other tasks before NASAs last space shuttle heads back to Earth.Space station flight engineers Mike Fossum and Ron Garan left the stations airlock for what was planned to be a 6-1/2-hour spacewalk.Normally, shuttle astronauts handle spacewalks while they are visiting the station, but Atlantis, which arrived at the station on Sunday for an extended nine-day stay, is short-handed.The spacewalk, the 160th devoted to station assembly and maintenance, is the last planned outing by the US astronauts for about a year and the final one supported by space shuttle crews.