CAPE CANAVERAL, Fla. - NASAfueled Discovery's external tank this morning in a bid to troubleshoot problemswith critical engine sensors and valves.
The shuttle launch team began the three-hour fueling operation around 5:30 a.m.By late morning, engineers were studying data and inspectors clad in orangecoveralls were scouring the launch pad.
Preliminary results are expected late this afternoon after more than 500,000gallons of supercold propellants (liquid oxygen and liquid hydrogen) aredrained from the 15-story tall orange fuel tank.
"From first look, we're having a very good experience with the tankingtest," NASA Administrator Michael Griffin said this morning during a visitto the Kennedy Space Center.
The shuttle team took advantage of the fueling test to get another look at howand where ice forms on the tank in addition to how the redesigned foaminsulation performs in general. The ice and debris inspection team remained atthe pad until almost noon, searching for dangerous ice build-up or otherproblems.
However, the primary reason for doing a second tanking test was to figure out aproblem that cropped up during a similar test in April.
During that test, sensors that serve as fuel gauges and a pressure-relief valvefailed to operate properly. The sensors produced an intermittent stream ofdata, and the valve opened and shut more than expected.
Engineers want to pinpoint the causes and fix them before launching theagency's first mission since the 2003 Columbia accident. The flight is set tolift off between July 13 and July 31.
The fuel-depletion sensors constantly measure the amount of propellant left inthe 15-story tank as the shuttle makes its nine-minute climb to orbit.
The relief valve keeps pressures within the tank at proper levels duringfuel-loading operations and flight.
NASA plans to move Discovery from launch pad 39B to the KSC Vehicle AssemblyBuilding as early as Tuesday so the ship can be outfitted with a new externaltank equipped with a fuel pipeline heater.
Managers decided to make that move after dangerous amounts of ice built uparound the 70-foot pipeline on the outside of Discovery's tank during lastmonth's fuel-loading test.
NASA feared ice could break off during launch and damage the shuttle's fragilethermal tiles and wing panels.
Serious damage to a wing panel doomed Columbia and its seven astronauts asre-entered Earth's atmosphere in a landing attempt on Feb. 1, 2003.
Publishedunder license from FLORIDA TODAY. Copyright ? 2005 FLORIDA TODAY. No portion ofthis material may be reproduced in any way without the written consent of FLORIDA TODAY.
Fixing NASA: Complete Coverage ofSpace Shuttle Return to Flight