Live At KSC: Tower Rollback, Tanking Test On Tap

LIVE IMAGES: The images above are from live video feeds in the Launch Complex 39 area at Kennedy Space Center, where shuttle Endeavour is being readied for a critical fuel-loading test. They will automatically refresh to the most up-to-the-minute image every 30 seconds.

BLOGGER UPDATE, 11:43 p.m,: The RSS is in motion.

BLOGGER UPDATE, 10:50 p.m.: The rollback of the Rotating Service Structure has been pushed back to 11:45 p.m. as a result of seasonal thunderstorms that slowed work at launch pad 39A earlier today. NASA contractor technicians at this hour still are working in the area around the leaky gaseous hydrogen vent line that prompted back-to-back launch scrubs on June 13 and June 17.

BLOGGER UPDATE, 9:30 p.m.: The rollback of the Rotating Service Structure has been pushed back to 11 p.m. as a result of seasonal thunderstorms that slowed work at launch pad 39A earlier today.

NASA is making final preparations for a crucial fuel-loading test at Kennedy Space Center, an exercise that will determine whether shuttle Endeavour and seven astronauts will make a launch attempt on July 11 or delay until late July or August.

A 13-story-tall service tower will start moving back away from the shuttle around 9:30 p.m. tonight, and then at 7 a.m. Wednesday, NASA and contractor engineers will begin to load a half-million gallons of liquid hydrogen and liquid oxygen into the shuttle's 15-story external tank.

The tank will reach the 98-percent full level between 9 a.m. and 9:15 a.m. That's the point at which dangerous gaseous hydrogen leaks cropped up prior to launch attempts on June 13 and June 17, triggering back-to-back launch scrubs.

A higher-than-allowable leak Wednesday would likely force NASA to roll Endeavour back to the Kennedy Space Center Vehicle Assembly Building to swap external tanks -- and that move would push the next launch attempt back to late July or early August.

You can it all live here in The Flame Trench. The live video feeds above will automatically refresh every 30 seconds, providing what amounts to sequential still video of the rollback tonight of the Rotating Service Structure. The operation is set to begin at 9:30 p.m. and should take about 45 minutes to complete.

You can also watch live NASA TV coverage of the tanking test beginning at 7 a.m. Wednesday. Simply click the NASA TV box at the righthand side of the page to launch our NASA TV viewer and be sure to refresh this page for periodic updates.

NASA and contractor engineers responded to a Call-To-Stations in Firing Room 4 of the Launch Control Center at 8:30 p.m. last night, and countdown clocks picked up at T-Minus 33 hours at 9 p.m.

Technicians today are completing ordnance operations at the launch pad and also will be prepping the shuttle's main propulsion system and its three main engines for the cryogenic fuel-loading operation.

NASA engineers traced the leaks to an external tank attachment assembly that is slightly misaligned. The misalignment caused a seal within a gaseous hydrogen vent line to pull out of place slightly, creating a leak path for the highly flammable substance.

NASA removed that seal and replaced it with an alternative that is expected to help stop the leaks. The vent line was reinstalled at the pad over the past weekend, clearing the way for a countdown to the tanking test.