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Shuttle set to return to flight after 2 1/2 years

Posted on: Wednesday, 13 July 2005, 07:08 CDT

By Deborah Zabarenko

CAPE CANAVERAL, Fla. (Reuters) - Shuttle Discovery was "go for launch" on Wednesday in NASA's first human space mission since the fatal Columbia accident 2 1/2 years ago.

The U.S. space agency cleared the shuttle for fueling before dawn, but a faulty heater delayed that process by more than an hour. NASA officials said there was ample time to fill the fuel tank and launch as scheduled at 3:51 p.m. (1951 GMT).

It was the second glitch in the final hours of the countdown. On Tuesday, a temporary plastic window cover fell from the roof of the cockpit and damaged two tiles near the vehicle's tail; these were replaced and NASA called it a minor issue.

Weather was the main potential obstacle to an on-time liftoff; an afternoon thunderstorm -- common in Florida in July -- could force a delay. NASA forecasters predicted a 60 percent chance of favorable weather, meaning no adverse conditions within 20 nautical miles of the launch pad.

Discovery's flight is meant to kick-start the stalled construction of the International Space Station and to be the first step on the road back to the moon and to Mars and beyond.

This flight begins the last chapter for the three-ship shuttle fleet, which has been grounded since Columbia disintegrated over Texas on Feb. 1, 2003, killing all seven astronauts.

The shuttles are set to retire for good in 2010 after about 20 construction flights to the station. NASA's new administrator, Michael Griffin, said the shuttles will be succeeded by a new generation of spacecraft and there is no thought of extending the shuttle fleet's service after that.

By 2010, Griffin said on Tuesday, the shuttles will have been in use nearly three decades.

"That's enough," he said. "It's time to take what we have learned and move on."

INHERENT RISKS

Even with all this experience, Griffin acknowledged that the shuttles remain experimental test vehicles, and their flights carry inherent risks.

Problems with the shuttle's 2.5 million parts are not ruled out on this mission and $1 billion and countless hours of manpower spent to avoid a repeat of the Columbia disaster do not eliminate the dangers of a shuttle mission.

Columbia tore apart on its re-entry into the atmosphere because falling foam from the external fuel tank had knocked a hole in its wing during liftoff 16 days before. When the shuttle returned to the Earth's atmosphere, superheated gases ate into the breach.

NASA's efforts since have been directed at minimizing the possibility of falling debris and one of Discovery's main tasks will be to see whether those efforts have paid off, and to try out experimental repair techniques if they have not.

The conditions Discovery and her crew, commanded by veteran astronaut Eileen Collins, will face are daunting. Its two solid rocket boosters will pour out 6.5 million pounds (3 million kg) of thrust and enough energy to light 87,000 homes for a day.

Discovery's other mission is to deliver needed supplies to the International Space Station, a 16-nation project.

Construction of the station has been on hold since the three remaining space shuttles were grounded after the Columbia accident, and it has been run by a two-man skeleton crew.

The station will serve as a safe haven for shuttle astronauts if Discovery is damaged and has enough oxygen, water and supplies to accommodate the seven-person crew for about eight weeks. It will provide the same function to the next scheduled shuttle mission in September.

After that, Griffin said, shuttle missions will be on their own because NASA will not be able to reserve a second shuttle to act as a rescue craft and still keep to the station's construction schedule.

Under a new vision for space exploration announced in 2004 by President Bush, the shuttle's return to flight and the completion of the space station are essential steps toward the shuttle fleet's retirement.

Source: REUTERS

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