Article Posted on : - Feb 24, 2011

Space shuttle Discovery rests at Launch Pad 39 A. A NASA photo

CAPE CANAVERAL, FLORIDA) (AFP): Discovery, NASA's oldest and most journeyed space shuttle, is poised to launch Thursday on its final mission, wrapping up a near three-decade legacy of orbital travel.

When the storied spacecraft lifts off at 4:50 pm (2150 GMT), it will mark the beginning of the end of the US space shuttle program, with Discovery, the first of the remaining three shuttles headed for retirement this year.

The closure of the US shuttle program will forge a gaping hole in the American space mission, and leaves astronauts to rely on the Russian Soyuz space capsule for transport to the orbiting International Space Station.

But concerns for the future were brushed aside as excitement mounted at Kennedy Space Center for Discovery's mission, with technical checks moving along smoothly and no hint of the fuel tank woes that delayed the launch in November.

"Everything is on track and going beautifully with the countdown," said mission management team director Mike Moses.

"We're really looking forward to a very action-packed, successful mission."

Cracks on Discovery's external fuel tank emerged just before launch more than three months ago, causing engineers to puzzle for many weeks over the cause and how to fix it.

In January, engineers agreed that installing small metal strips, called radius blocks, on the 6.7 meter- (22-foot-) long U-shaped aluminum brackets, called stringers, would reinforce their strength.

Shuttle launch director Mike Leinbach said the teams preparing Discovery this time had found "no problems at all" as they count down toward lift-off.

"We're not tracking any issues and it looks like Discovery will fly this time," said Leinbach.

The rotating service structure around Discovery was rolled away Wednesday evening, revealing the shuttle on the launch-pad for the first time.

The six-member crew of astronauts headed to bed at 11 pm (0400 GMT) and were to awaken at 7:00 am (1200 GMT) for the launch Thursday, NASA said.

The loading of the external fuel tank was to begin at 7:25 am (1225 GMT). The astronauts were expected to board the shuttle at around 1:35 pm (1835 GMT).

The mission will be led by Commander Steven Lindsey, pilot Eric Boe and astronauts Alvin Drew, Michael Barratt, Steve Bowen and Nicole Stott.