Shuttle Endeavor RSS Rollback Completed, Fueling to Begin Sunday Night

NASA-- The opening of the rotating service structure (RSS) that protected Endeavour on Launch Pad 39A and provided access to the shuttle's systems began its retraction Sunday at 11:44 a.m. EDT and completed at 12:24 p.m. This major milestone paves the way to loading the giant external fuel tank with about 500,000 gallons of propellant.

The STS-134 crew members are sleeping and are scheduled to be awakened at about midnight to gear up for launch. The weather forecast for Endeavour's 8:56 a.m. liftoff to the International Space Station calls for a 70 percent chance of favorable conditions.

Launch Countdown Highlights (All Times Eastern)

11:30 p.m. NASA TV: External Tank Fueling Coverage Begins
11:36 p.m. Countdown resumes at the T-6 hour mark
Midnight Crew wakeup
12:21 a.m. Liquid Hydrogen Low Level Cutoff sensors go "wet"
12:30 a.m. Crew breakfast
12:36 a.m. Liquid Hydrogen "fast fill" begins
1 a.m. Crew final medical exams
1:51 a.m. LH2 "topping" begins
2:36 a.m. Countdown enters a 2 1/2 hour hold at the T-3 hour mark
3:30 a.m. Launch Coverage Begins on NASA TV and the Launch Blog
4:31 a.m. Astronauts receive a weather briefing from the Ascent Team
4:41 a.m. Astronauts suit up for launch
5:06 a.m. Countdown resumes at the T-3 hour mark
5:11 a.m. Crew departs for Launch Pad 39A
5:41 p.m. The astronauts begin to board Endeavour
6:56 a.m. Endeavour's hatch is closed and latched for launch
7:46 a.m. Countdown enters a 10-minute built-in hold at the T-20 minute mark
7:56 a.m. Countdown resumes at the T-20 minute mark
8:07 a.m. Countdown enters a ~40-minute built-in hold at the T-9 minute mark - MMT conducts final poll "Go-No Go" for launch
8:52 a.m. Countdown resumes at the T-9 minute mark
8:56:26 a.m. Launch of Endeavour on the STS-134 Mission
9:04:49 a.m. Main Engine Cut-Off (MECO)
~ 10 a.m. NASA TV: Post launch news conference