Shuttle Launch Postponed Due To Fuel Cell Problem

An erratic reading on a fuel cell has forced NASA to push back a launch attempt by at least a day while they investigate the problem.

The fueling of the external tank had yet to start when one of three cells that provide electricity to Atlantis gave an erratic reading. The space agency planned to further examine the problem, and if possible try to launch at 12:03 p.m. EDT Thursday.

"The launch rules say you need to have three good, operating fuel cells," said NASA spokesman Bruce Buckingham. "We're going to see if it's something that's a real problem or whether it's something we can rectify."

The problem was discovered shortly before an overnight meeting to decide whether to start pumping the shuttle's fuel tank with supercold liquid hydrogen and liquid oxygen. When the shuttle's fuel cells were powered up, a low voltage reading came from one of the units, and the other two spiked up to compensate.

Fuel cell problems have forced launch delays before and even ended missions early.

The second flight of space shuttle Columbia in 1981 was delayed because of a low pressure reading on an oxygen tank that fueled a cell. Columbia's five-day mission was then cut short by almost three days when the fuel cell failed.

In 1995, space shuttle Endeavour's launch was delayed eight days so workers could remove and replace a bad fuel cell that was registering higher than allowable temperatures.

A 1997 flight of space shuttle Columbia returned to Earth four days after launch when a cell failed in orbit. The fuel cell had shown some erratic readings before the launch but the shuttle was cleared to fly. It was only the third time a shuttle mission had ended early, but the mission was rescheduled and Columbia launched again a few months later.

If the Atlantis does not get into space this week, NASA may have to push the launch back to sometime in October. The launch window is pretty tight.