In a shot from his helmet cam, astronaut Steve Robinson holds a piece of protruding gap filler he has removed from between the thermal tiles on the underside of Discovery, revealing the red adhesive that was used to hold it in position. Photograph: Nasa TV/Reuters
2.30pm update: In the end, he didn't need the homemade hacksaw. With just his fingers, astronaut-turned-repairman Steve Robinson has just performed an audacious in-flight fix to the space shuttle Discovery, allowing Nasa and the nation the chance to catch breath for the first time today, writes Richard Luscombe in Florida.
Stunning pictures from Robinson's "helmet-cam" broadcast live on the web and on Nasa's own TV station showed him pulling out the two protruding fragments of ceramic-cloth 'gap fillers' from Discovery's belly. "It looks like the patient is cured," he declared after the second rectangular strip came away easily with just a gentle tug.
Mission Control in Houston declared it "a great job" as Robinson, still dangling from the space station's robotic arm, headed back to the shuttle after an unprecedented spacewalk lasting more than four hours, but not before fellow space-walker Soichi Noguchi managed to snap a few pictures for the Robinson family album of a new national hero.
"You'll spend the next four years signing autographs," teased astronaut Andy Thomas, who choreographed Nasa's first in-orbit repair to a spacecraft. Despite the light mood, the relief aboard Discovery, and among the space agency's beleaguered engineers, is enormous as a potential danger to the shuttle's safe return to Earth is eliminated.
12.18pm: It might not be prime time entertainment given that it's only just after 6.30am across the eastern United States, but millions of Americans are waking up to a transfixing saga in progress on their television screens - Nasa's riskiest ever spacewalk to make safety fixes to the shuttle Discovery.
Two astronauts, Steve Robinson and Soichi Naguchi, are almost two hours into a planned seven-hour spacewalk and are currently attaching an external stowage platform on to the side of the International Space Station, to which Discovery is docked.
But the real purpose of the walk has yet to be achieved. The country is waiting with bated breath for Robinson to swing to the shuttle's underside attached to the space station's robotic arm and, using only his gloved hands, forceps and a makeshift hacksaw, remove two small protruding pieces of ceramic cloth called gap fillers that Nasa fears could endanger the shuttle's safe return to earth next Monday if they are not removed.
The astronauts were in bullish mood as the spacewalk began at 4.48am, Naguchi yelling "All Right!" as he emerged from the shuttle's hatch to the beautiful sight of the Earth spinning 224 miles below. Viewers on Nasa's own TV channel were treated to a lesser panorama - a close up of the Japanese astronaut's feet dangling beside a large metal shelf.
