Such inspections are routine since damage to a fuel tank lead to the death of Columbia's seven astronauts during re-entry in 2003. Despite this, NASA had been considering skipping the inspection after Discovery's mission to the station went a day longer than planned due to an unscheduled space walk was required to full retract a stubborn solar panel.
The extended mission means the shuttle is now forced to use one of two days of emergency fuel set aside to allow for landing delays due to bad weather. Bad weather delayed Discovery's launch for two days last week, and the shuttle will now only have 24 hours of reserves for its fuel cells should weather delay its return to Earth.
Discovery is expected to land at the Kennedy Space Center on Friday afternoon. With only one bad weather day in reserve, NASA is expected to prepare backup landing sites at Edwards Air Force Base in California and White Sands, New Mexico. Preliminary weather forecast are for possible low clouds and rain at Kennedy and high cross winds at Edwards on Friday, but White Sands is currently clear for Friday.