[sarex] Reuters version Shuttle scrub

[K6due@xxxxxxx]

NASA Scrubs 100th Shuttle Launch 

By Brad Liston

CAPE CANAVERAL, Fla. (Reuters) - NASA scrubbed the launch of space shuttle 
Discovery for at least 24 hours on Thursday citing concerns about the 
shuttle's large external fuel tank.

Discovery and a crew of seven astronauts had been scheduled to lift off at 
9:38 p.m. on a mission to add two new segments to the International Space 
Station (news - web sites), waiting in orbit some 220 miles above Earth.

The space agency said it was not sure if a problem existed with Discovery's 
tank, but film from the launch of space shuttle Atlantis in September 
revealed that an explosive bolt used to separate the tank from the shuttle 
orbiter was protruding slightly when it should have retracted.

Any change in the configuration of the shuttle, which reaches speeds of five 
miles per second by the time it is in orbit, is cause for concern to NASA's 
engineers.

In this case, the concern was that any unintended contact might cause the 
fuel tank to pitch forward and strike the nose of the shuttle, causing a 
catastrophic accident.

NASA managers said the decision to scrub Thursday's launch was precautionary, 
and they had no reason to believe the problem existed on Discovery or that it 
would lead to disaster if it did. Atlantis launched safely with the problem.

``We do not want to get 'go' fever,'' said Jim Halsell, a NASA manager for 
launch integration. ``We don't know, and we don't have any reason to believe, 
that we have a problem.''

The bolt in question was part of a pyrotechnic nut-and-bolt assembly on the 
fuel tank itself. Once a small explosive charge is used to break apart the 
nut, the spring-loaded bolt is supposed to retract into a housing.

On the Atlantis launch, a 35mm camera mounted on the rear of the shuttle 
filmed the separation and recorded the bolt sticking about 2.5 inches out of 
its housing.

Engineers discovered the problem on Wednesday during routine processing of 
Atlantis and its systems following the September mission. It was only by 
chance, NASA said, that Discovery happened to be ready for launch.

``It was just part of our normal data review,'' said Bill Gerstenmaier, 
another launch integration manager.

Discovery's mission would be the 100th in the almost 20-year history of the 
U.S. shuttle program, and NASA laid out an ambitious agenda.

The success of the next three space-station missions largely depends on the 
ability of Discovery's crew to add two new segments to the station.

Future shuttle flights will need the new docking port Discovery carries in 
its cargo bay alongside another segment, the Z-1 Truss, designed to support a 
240-foot array of solar paneled ``wings,'' the largest ever deployed in space.

The solar panels are scheduled for launch in November. In January, NASA plans 
to add the U.S. laboratory module, Destiny, powered by the electricity 
generated by those solar panels.

Unless the Discovery astronauts can deliver the goods, those missions will 
not move forward.

Also, much of the work scheduled for the Expedition One crew, the first 
long-duration crew, would have to be delayed. The two Russians and their 
American commander are scheduled to arrive aboard a Russian Soyuz capsule in 
November for a four-month stay.

The Discovery mission should provide good television for viewers on Earth. 
Four spacewalks on four consecutive days are scheduled as astronauts 
reconfigure the boxy Z-1 Truss for space operations, help guide the docking 
port to its berth and test methods of getting stranded, dead or stricken 
spacewalkers back to the shuttle.

NASA has estimated some 160 spacewalks will be needed to complete the space 
station by 2006. 

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