NASA Mulls Fuel Tank Test for Next Shuttle Flight

Inside the Vehicle Assembly Building at NASA's Kennedy Space Center, external tank number 119 hangs suspended horizontally in preparations for its fuel sensor swap. CREDIT: NASA/Cory Huston.

CAPE CANAVERAL - NASA is mapping out plans to test shuttle Discovery's external tank at its Kennedy Space Center launch pad, but a final decision on whether to proceed with the fuel-loading operation still is pending.

The test would involve pumping more than a half-million gallons of super cold liquid hydrogen and liquid oxygen into the 15-story tank to test changes made to it, agency officials said Wednesday.

Among other things, the test - which would take place about June 1 - would enable engineers to determine whether four new liquid hydrogen fuel-depletion sensors in the tank are working properly.

Kyle Herring, a spokesman for NASA's Johnson Space Center in Houston, said engineers have been asked to draw up plans for a test, but managers still have not made a final decision on whether to carry it out.

The fuel-depletion sensors serve the same purpose as automobile fuel gauges and also provide a back-up means of making sure the shuttle's main engines shut down properly.

A malfunction could prompt a premature shutdown, which could lead to an emergency landing attempt, or the engines could continue running until all fuel was exhausted, potentially triggering a catastrophic failure.

One of the four sensors originally installed in Discovery's tank produced unexpected readings during an electrical test in late February. Managers subsequently decided to replace all four, a move that forced NASA to delay its second post-Columbia test flight from May to July.

NASA encountered problems with the same sensors during a fuel-loading test before Discovery's launch last July. The troubles did not recur during a subsequent launch countdown and NASA proceeded with the flight.

KSC spokesman Bruce Buckingham said NASA has enough time in its launch-processing schedule to accommodate a tanking test. Discovery remains scheduled for a May 19 move to its pad and launch still is targeted for July 1.

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