The threat of cloud cover forced NASA managers to wave off STS-113's first landing attempt for today at Kennedy Space Center, Fla. Attention now turns to Space Shuttle Endeavour's second opportunity of the day. If it is selected, the de-orbit burn will occur during orbit 170 at 3:19 p.m. CST (2119 GMT) and landing at 4:26 p.m. CST (2226 GMT).