As a result, the Lunar Reconnaissance Orbiter, or LRO, and Lunar Crater Observation and Sensing Satellite, or LCROSS, are set to lift off together aboard an Atlas V rocket on Thursday, June 18th. There are three launch opportunities from Cape Canaveral Air Force Station in Florida: 5:12 p.m., 5:22 p.m. and 5:32 p.m. You may recall that NASA managers had to postpone Endeavour's planned June 13th liftoff due to a leak associated with the gaseous hydrogen venting system outside the shuttle's external fuel tank. The system is used to carry excess hydrogen safely away from the launch pad.
The LRO and LCROSS launch was moved to June 18th to accommodate Endeavour's June 17th liftoff. If Thursday's liftoff of LRO and LCROSS is postponed 24 hours, the launch times Friday are 6:41 p.m., 6:51 p.m. and 7:01 p.m. Saturday's opportunities are 8:08 p.m., 8:18 p.m. and 8:28 p.m. Endeavour's 16-day STS-127 mission to the International Space Station will feature five spacewalks and complete construction of the Japan Aerospace Exploration Agency's Kibo laboratory. Astronauts will attach a platform to the outside of the Japanese module that will allow experiments to be exposed to space.
LRO is scheduled for a one-year exploration mission at a polar orbit of about 31 miles, or 50 kilometers, the closest any spacecraft has orbited the moon. The primary objective of LRO is to conduct investigations to prepare for future explorations of the moon. Launching with LRO is LCROSS, a partner mission that will search for water ice on the moon by sending the spent upper-stage Centaur rocket, about the size of a sports utility vehicle, to impact part of a polar crater in permanent shadows. LCROSS will fly into the plume of dust left by the impact and measure the properties before also colliding with the lunar surface.