The space shuttle Endeavour began her trip out to her seaside launch pad at midnight this morning to prepare for her flight on one of two missions - a shuttle emergency rescue flight or a space station construction and servicing mission.
First motions from the massive vehicle assembly building began at 12 midnight, with the entire shuttle stack beginning it's ride at about 1 mph down a gravel road to launch pad 39-B.
Meanwhile, over at pad 39-A, shuttle Atlantis sits awaiting her next flight on May 12th to repair and upgrade the Hubble Space Telescope. Because Hubble is in a different orbital inclination (28.45 degrees to the equator) than the space station is (51.65 degrees), Atlantis could not get over to the station if she was damaged while on orbit. Damage coming from foam falling off the external tank and smashing the belly of Atlantis - such was the case of the doomed shuttle Columbia in 2003.
Post-Columbia rules dictate the need of having a back-up shuttle ready to go if an orbiter is damaged while in space. Atlantis STS-125 mission in May will be the final non-space station flight of the shuttle program. Read our background story on how the emergency rescue mission would work.
Between today and through Atlantis' mission, Endeavour will be prepared for the mission no one wants - STS-400. Near the end of Atlantis' 11-day flight, shuttle program managers will give the green or red light following on orbit crew inspections of the thermal tiles which surround the belly, wing leading edges and nose section.
If everyone is comfortable that Atlantis is healthy, then Endeavour will begin her move from pad 39-B south to Pad 39-A, and begin preperations for the much wanted STS-127 mission to the international space station.
Once Endeavour departs pad B, then ground crews will begin full scale work to prepare the northern pad for the first Ares 1X unmanned rocket test launch in late August.