Two astronauts stepped out of the International Space Station today for a spacewalk in which they hope to make shuttle flights safer by bouncing around on the end of a 30-metre boom.
Piers Sellers and Michael Fossum were to strap their feet into a foot clamp on the boom, then bend, twist and bounce to test its stability as a platform for emergency repairs.
"Enjoy the view, gentlemen," Mission Control capsule communicator Megan McArthur told the two men as they emerged from the station into space. The oddball boom experiment is part of Nasa's effort to improve shuttle safety following the 2003 Columbia disaster that killed seven astronauts.
Nasa wants to see if the boom, which is a combination of the space shuttle Discovery's 15-metre robot arm and a 15-metre extension, will hold astronauts steady enough to repair parts of the spacecraft unreachable with just the robot arm.
Repairs would be necessary if there were damage to a shuttle's heat shield, which protects the spacecraft during its fiery return to earth.
When Columbia launched, insulating foam from the fuel tank shook loose and broke a wing heat shield.
This breach allowed hot gases to destroy the orbiter 16 days later when it re-entered the atmosphere.
Mr Sellers and Mr Fossum, who along with five other astronauts flew to the station aboard shuttle Discovery on Thursday, were to be out in space 6 1/2 hours on the first of three spacewalks on what is now scheduled to be a 13-day flight.