The crew of the space shuttle Discovery prepared for a return trip to Earth Wednesday by conducting a last inspection of its heat shield following 10 days in space on a rewiring mission to the International Space Station, reported Deutsche Presse Agentur dpa. Astronauts used a robotic arm to make sure the heat shield had not been damaged by any micrometeoroids or other space junk during its time at the ISS. The safety of shuttle heat shields have been a major concern for NASA following the disintegration on re-entry of the shuttle Columbia in 2003. That accident was blamed on a large piece of insulating foam breaking off the external fuel tanks on lift off. Discovery undocked from the ISS on Tuesday and is slated to land at Kennedy Space Centre in Florida on Friday afternoon. The shuttle leaves behind US astronaut Sunita Williams, who is the newest member of the ISS crew. German astronaut Thomas Reiter, a departing ISS crew member, will return to Earth on the Discovery after more than five months in space. Discovery astronauts spent an extra day at the ISS so they could make an unplanned fourth spacewalk on Monday to fold a solar panel that had failed to mechanically retract earlier in the mission. In three earlier space walks, astronauts completed rewiring work on the station's permanent electrical system.
