For NASA, learning working-in-space lessons has been the manned spaceflight program's primary challenge during the last two decades.
Space shuttle Endeavour glided to a smooth landing Friday morning at Kennedy Space Center, completing a successful 16-day mission to upgrade the international space station.
After two days of debate, space shuttle program managers cleared Discovery for a launch attempt Tuesday at 12:36 a.m. CDT.
Launch date: July 11
Orbiter: Endeavour. Crew: Seven. Commander Mark Polansky; pilot Doug Hurley; mission specialists Dave Wolf, Christopher Cassidy, Tom Marshburn, Tim Kopra; Canadian Space Agency astronaut Julie Payette.