By Irene Klotz
CAPE CANAVERAL, Florida (Reuters) - A pair of shuttle Discovery astronauts put on spacesuits and floated outside the International Space Station on Wednesday with a list of chores to help get the outpost ready for life after shuttle retirement.
Spacewalkers Stephen Bowen and Alvin Drew had a late start due to a leak in Bowen's pressurized suit. After checking his helmet, gloves and boots, crewmates found a damaged seal in a canister that purges carbon dioxide from the spacesuit.
The seal was replaced, clearing the way for Bowen and Drew to leave the station's airlock around 11 a.m. EST (1600 GMT) for the second of two spacewalks planned during Discovery's eight-day stay at the station.
The astronauts' to-do list includes venting ammonia from a failed pump module that NASA plans to return to Earth on the final shuttle flight in June, installing a camera and protective lens cover on the station's robot arm, adding a light to a crew equipment cart, and removing an equipment pallet from outside Europe's Columbus module.
The six-member Discovery crew, on the 133rd mission in shuttle history, already has completed the primary goals of the 12-day flight. They attached an outside storage platform for spare parts shortly after reaching the station on Saturday. On Tuesday, they installed a combination storage room and mini-research lab to the outpost, completing assembly of the U.S. side of the station.
The space station is a $100 billion project of 16 nations that has been under construction 220 miles above Earth for the past 12 years. Russia plans to launch a final research module in May 2012.
Discovery's mission is the 39th and last for NASA's oldest surviving spaceship. Upon return to the Kennedy Space Center in Florida next week, Discovery will be prepared for its new mission as a museum piece.
Discovery is promised to the Smithsonian National Air and Space Museum in Washington, D.C. Retirement homes for sister ships Endeavour and Atlantis, which are scheduled to make their final flights in April and June, have not yet been announced.
NASA is ending the shuttle program due to high operating costs and to free up money to develop new spacecraft capable of flying to the moon, asteroids and other destinations in the solar system.
(Editing by Jane Sutton and Bill Trott)