Endeavour's Tank to be Tested Wednesday

NASA will load space shuttle Endeavour's external fuel tank with its super cold fuels on Wednesday to test a repaired seal which had forced two launch scrubs in June due to leaking gaseous hydrogen.

The Kennedy Space Center launch team will start at 7 am EDT, loading nearly 500,000 gallons of liquid oxygen and liquid hydrogen into the huge rust-colored fuel tank. Two hours into the tanking test is where engineers first discovered the gaseous hydrogen leak from the Ground Umbilical Carrier Plate (GUCP) coming from the tank during launch attempts on June 13 and 17.

The GUCP is what allows gaseous hydrogen (GH2) to leave the fuel tank as the hydrogen's liquid form evaporates away as the shuttle stack awaits liftoff. The GH2 is moved from the tank in a controlled manner. It flows from the tank and out to the launch pad's hydrogen vent arm which is attached to the tank via the GUCP. From the pad, the GH2 flows out away where a burning flame adjacent to the pad burns it off.

Thus, at about 9AM, the launch team will either begin to see leaking GH2 or run through the entire fueling test and not see it at all. A Kennedy news conference is scheduled for about 1PM to discuss the results of the launch team's tanking test.

Based on a positive tanking day on Wednesday, then space shuttle launch managers will likely continue to move forward to launch Endeavour on July 11 on a 16-day mission to the international space station. Launch time is 7:39 pm.

Endeavour's crew includes commander Mark L. Polansky, pilot Douglas G. Hurley, and mission specialists Christopher J. Cassidy, Thomas H. Marshburn, David A. Wolf, Julie Payette (Canadian Space Agency) and Timothy Kopra. Kopra will begin a two month stay aboard the station as he replaces current resident Koichi Wakata of the Japanese Space Agency.

SpaceLaunchNews.com will have LIVE television coverage of both the tanking test and the latter news conference. Also, via your iPhone, PDA or Blackberry follow our LIVE SLN updates via Twitter. User name: @spacelaunchnews.