NASA may bend safety rules for launch

Nature, not the fuel gauge, could decide whether shuttle takes off.

CAPE CANAVERAL, Fla. -- With the countdown entering its final hours and a fuel gauge problem still unexplained, NASA said it is prepared to bend its long-standing safety rules to launch the shuttle today on the first flight since Columbia's doomed mission 2 1/2 years ago.

Discovery and a crew of seven were set to blast off for the international space station at 10:39 a.m., after a two-week delay caused by a malfunctioning hydrogen fuel gauge in the spaceship's giant external tank.

Nature, rather than the fuel gauge, could ultimately decide whether Discovery takes off. Forecasters put the odds of good launch weather at 60 percent, with rain and storm clouds both posing threats.

NASA had the paperwork ready to go in case the equipment trouble reappeared and the space agency's managers decided to press ahead with the launch with just three of the four fuel gauges working. That would mean deviating from a rule instituted after the 1986 Challenger explosion.

"There's very little in life that is 100 percent guaranteed, and there's probably less in rocket science that's 100 percent guaranteed," deputy shuttle program manager Wayne Hale said over the weekend. "That is part of the risk we take."

The fuel gauges are designed to prevent the main engines from running too long or not long enough, in case the fuel tank is leaking or some other major breakdown occurs. An engine shutdown at the wrong time could prove catastrophic, forcing the astronauts to attempt a risky emergency landing overseas, or leading to a ruptured engine.

Both Hale and NASA administrator Michael Griffin noted that multiple failures would have to occur in multiple systems for the worst-case scenario to come true.