This spectacular NASA photo from the Kennedy Space Center shows how, for the first time since July 2001, two shuttles are on launch pads at the same time. Atlantis is in the foreground on Launch Pad A, and Endeavour is behind it on Launch Pad B.
http://www.nasa.gov/images/content/271560main_08pd2730.jpg
Endeavour was moved into position Friday so it could be on standby in the unlikely event that a rescue mission is necessary for the Atlantis' planned October 10 mission to repair NASA's Hubble Space Telescope, the agency said.
Once Endeavour is cleared from its rescue spacecraft duty, it's scheduled to move to Launch Pad A for planned November 12 mission to the International Space Station.
What makes the Hubble repair mission particularly dangerous is that if Atlantis gets seriously damaged during flight, the seven astronauts would be stranded--they couldn't just hang out at the International Space Station waiting for a ride.
Plus, as the Associated Press points out, Atlantis "faces an estimated 1-in-185 chance that a piece of space junk or a micrometeoroid will cause catastrophic damage to their ship." Those odds are greater than for a typical shuttle flight because of Hubble's unusually high and debris-filled orbit.
Clint Bradford, K6LCS / KAF3359 909-241-7666