Discovery is set for a launch attempt Friday at 11:59 p.m., as engineers will evaluate a liquid hydrogen valve that developed problems during tanking operations Tuesday evening.
Exploration History
This Month in Exploration
Visit every month to find out how aviation and space exploration have improved life for humans on Earth and in space.
NASA Missions in History
Featured Missions
Discovery's Next Launch Attempt Late Friday
LRO Sends Back First Moon Images
NASA's Lunar Reconnaissance Orbiter is now in lunar orbit. The Lunar Crater Observation and Sensing Satellite will impact the moon in October.
International Space Station: Expedition 20
Commander Gennady Padalka leads a six-member crew of astronauts from Canada, Europe, Japan, Russia, and the United States.
 "International Space Station")
 "orion orbiting the moon")