Article Posted on : - Mar 06, 2011

Space shuttle Endeavour during its 22nd flight to the ISS. A NASA photo

HOUSTON (PTI): While Discovery astronauts are still in the orbit busy rejuvenating the International Space Station's air system, NASA is gearing up space shuttle Endeavour for an historic final trip to the launch pad.

Shuttle Endeavour has been moved from maintenance hanger to vehicle assembly building at the Kennedy Space Center in Florida to get attached to the fuel tank and rocket booster that will help its final space voyage on April 19.

NASA plans to roll Endeavour out to its seaside launch pad for the final time Wednesday, the day Discovery, flying a last mission of its own, is due to land at the Kennedy Space Center's landing strip.

Initially, Discovery was slated to land on March 8 with Endeavour moving to the launch the next day.

NASA is retiring its three winged orbiters later this year after 30 years of shuttle flight.

Discovery's current mission was launched on February 24, beginning what is now a 13-day mission to deliver a storage room and humanoid robot, called Robonaut 2, to the International Space Station.

After Discovery's mission ends, NASA plans to fly just two more flights before shutting down the shuttle programme.

The final flight of Endeavour will deliver a $1.5 billion astrophysics experiment to the ISS.

The flight will be followed by shuttle Atlantis’ launch on June 28 to deliver spare parts and extra supplies to the orbiting laboratory.

Both remaining shuttle launches are expected to draw record crowds of spectators hoping to see a NASA orbiter blast off before the programme ends.

Discovery's launch last week drew an estimated 40,000 people, NASA officials have said.

When Discovery rolled out to the launch pad for its final flight on January 31, about 3,000 people – mostly shuttle workers and their families— turned out to see the event, official added.

Meanwhile, Discovery has been linked to the space station for an entire week as the two space crews, 12 astronauts in all, worked together to add a new room, robot and spare parts to the orbiting lab.

Discovery astronaut Mike Barratt teamed up with space station resident and European Space Agency astronaut Paolo Nespoli for one of the crews' main tasks: fixing part of an air-scrubbing system in the US Destiny Laboratory.

This system, called the Carbon Dioxide Removal Assembly (CDRA), filters breathable air through the station by removing carbon dioxide.

During the mission's first spacewalk, the CDRA system in the Destiny Lab suffered a failure, said space station lead flight director Royce Renfrew.

"We've narrowed that down to what's essentially a short in the heater beds," Renfrew said in a briefing Friday.

One of those heater pads apparently has a short in it and we're going to operate on that heater pad.

Mission specialists Steve Bowen and Alvin Drew will spend some time in the station's Quest airlock, where the suits they wore for their two spacewalks are being stored.

Bowen and Drew will start packing up these spacesuits in preparation for their return to Earth.

The other astronauts, meanwhile, will continue transferring cargo out of the station's new storage module – the Permanent Multipurpose Module – which was delivered by Discovery's crew.

They will also retrieve supplies out of the HTV-2, an unmanned Japanese cargo ship that is currently docked at the station.

Some of these supplies will be reorganised and tucked away in the closet-like storage module.

On Thursday the shuttle and station crews received a phone call from President Obama, who joked with the astronauts about their newest crew member: the humanoid robot Robonaut 2, or R2 for short.

Robonaut 2 rode aboard Discovery to the International Space Station inside the storage module.

The dexterous robot was recently taken out of the module, but still remains packed in its foam case.

And while the robot will not be fully unpacked during Discovery's visit to the station, it could meet its new station crewmembers earlier than originally scheduled.

NASA is now planning to unpack Robonaut 2 earlier than planned, with its activation slated for sometime between March 10 and March 28.

This is because mission planners would like to dispose of all the foam used to pack Robonaut 2 on the HTV-2 spacecraft, which will be intentionally released from the station on March 28 to burn up in the Earth's atmosphere.

Discovery's 13-day STS-133 mission will be the shuttle's last before being retired from service after 39 trips into space, including 13 visits to the ISS.