Houston, July 5: Astronauts on the shuttle Discovery awoke to their first full day in space today and prepared to inspect their orbiter for damage after launching from Florida on a flight NASA hopes will get the troubled US space program back on track.
Photos and videos from Tuesday's Fourth of July takeoff showed flecks of insulating foam flying off the shuttle's problem-plagued fuel tank after launch, but NASA executives said initial examinations revealed no cause for alarm.
The shuttle crew was to spend most of Wednesday using a robot arm to scan Discovery's most vulnerable parts with lasers and close-up cameras to see if the loose foam caused any nicks to the spacecraft's protective heat shield.
A 1.67 pound (756 gram) chunk of fuel tank foam was blamed for the Columbia disaster in 2003 after it slammed into the shuttle's wing at launch and later caused the orbiter to break apart over Texas, killing the seven astronauts on board.
Potentially dangerous foam also flew off on a subsequent shuttle mission last summer, raising questions about whether the spacecraft NASA has flown since 1981 could still be operated safely enough to finish the half-completed $100 billion International Space Station.
NASA spent $1.3 billion over the last three years to fix the fuel tank and make safety upgrades to the shuttle.
NASA managers had warned that the tank, covered with more than 4,000 pounds (1,818 kilograms) of foam, would continue to shed debris, but expected no pieces large enough to damage the shuttle in case of impact.
Shuttle program manager Wayne Hale said with one possible exception the foam pieces spotted on Tuesday were small, and only one appeared to strike the spacecraft. But he said the foam shook loose late enough in the launch that it appeared not to pose a danger because it hit with little force.
NO CAUSE FOR CONCERN ''I think the tank performed very, very well indeed, very pleased. As opposed to where we were last year, we saw nothing that gives us any kind of concern about the health of the crew or the vehicle or any cause to think we wouldn't be safe to fly the next tank,'' Hale said.
''It's all very minor, it's all very light,'' he said of the lauch debris.
The agency needs a successful mission to resume space station construction, which has been on hold since the Columbia accident and will require 16 shuttle flights to complete. Another accident or serious problem could ground the shuttle fleet permanently before its planned retirement in 2010.
Discovery is scheduled to link up with the space station on Thursday.
The shuttle's 12-day mission is meant to test fuel tank repairs and deliver badly needed supplies and equipment to the space station. The astronauts will make two spacewalks.
One will test a 50-foot (15-metre) extension to the shuttle's robot arm. Crews use the boom to inspect the ship for damage but NASA wants to know if it could be used to maneuver spacewalkers to inaccessible parts of the shuttle for repairs.
During the second spacewalk, astronauts Piers Sellers, a British-born climate scientist, and Michael Fossum, an American making his first spaceflight, will try to fix the space station's broken mobile transporter.
The transporter, a cart that travels on tracks on the outside of the space station, will be needed to install trusses and solar arrays on the space station. It has been broken since December.
A third spacewalk to test shuttle repair techniques will be performed if Discovery has enough fuel to extend the mission for a day.
Damage to Columbia at launch went undetected until it disintegrated 16 days later as it flew back into the atmosphere from space. Superheated gases entered the breach in a wing heat shield and caused the spacecraft's destruction.