News Service from House Harris

US: Astronauts scan Atlantis for damage, pursue Hubble

HOUSTON, Texas, May 12 AFP - Shuttle Atlantis astronauts on Tuesday scanned fragile heat shields aboard their spacecraft for signs of damage from launch debris as they raced toward a rendezvous with the Hubble Space Telescope.

Early results of Tuesday's 10-hour long inspection of the wings, nose and belly of Atlantis by the seven shuttle astronauts revealed no obvious signs of damage.

Atlantis was on course to rendezvous with the 560-kilometre high observatory Wednesday shortly after mid-afternoon.

As mission commander Scott Altman steers his ship close to the observatory, astronaut Megan McArthur will reach out with the shuttle's robot arm to grab the 13.2-metre long telescope.

Using the mechanical limb like a construction crane, McArthur will mount the telescope upright atop a circular work platform in the shuttle's cargo bay.

Early Tuesday, the astronauts sent commands that positioned the platform to await Hubble's arrival. They checked out the space suits that four of the shuttle's astronauts will wear during five spacewalks, as well as hand tools they will use for the task. The tool kit includes 180 pieces of equipment, most custom-made for Hubble's overhaul.

Monday's launch initiated a challenging, 11-day mission devoted to a final refurbishment of the 19-year-old space telescope, a collaboration between NASA and the European Space Agency.

The upgrade should extend Hubble operations by at least five years and equip the world's best known telescope to search for signs of the earliest star systems, provide a deeper understanding of dark energy and dark matter, and about the way planets form.

After lift-off, mission managers counted four small pieces of unidentified debris moving near Atlantis in tracking camera views of the shuttle's climb to orbit.

A brief camera survey of the spacecraft's crew compartment by the astronauts after launch revealed no obvious signs of damage, however.

"We have a great vehicle," said Bill Gerstenmaier, NASA's associate administrator for space operations. "This is a great start to a very challenging mission."

Tuesday's damage inspection of the wings and underside of the shuttle will test Gerstenmaier's optimism. The shuttle crew used a camera and laser-tipped extension of the shuttle's robot arm to carry out Tuesday's damage survey. The imagery was transmitted to Mission Control, where experts were to assess the pictures.

NASA expects to have preliminary results before the shuttle astronauts start the first of their spacewalks early Thursday.

The spacewalkers have trained to equip Hubble with new batteries and gyroscopes to fortify Hubble's electrical power and steering systems, one of the mission's highest priorities.

The spacewalkers will replace a computer that prepares the telescope for celestial observations and formats the pictures for transmission to Earth. The science instrument command and data handling computer experienced a partial electrical failure in late September, forcing NASA to postpone the mission from October to May while it prepared a replacement.

The spacewalkers intend to install a pair of new science instruments and make unprecedented repairs to the electronic circuitry within an older camera and spectrometer.

NASA has characterised the mission as the riskiest in the dozen shuttle visits to the International Space Station since the 2003 Columbia tragedy that claimed the lives of seven astronauts.

The disaster was blamed on an undetected breach of the protective heat shields caused by a launch day collision with a breakaway chunk of foam fuel tank insulation.

In the aftermath of the explosion, NASA made heat shield inspections a part of every mission and made plans to mount a rescue mission if the astronauts on future missions found damage that could not be repaired.

Circling the Earth much higher than the space station, Hubble is exposed to an accumulation of space debris from a satellite collision earlier this year, as well as the fragments left from previous spacecraft breakups.

While the space station offers weeks of refuge for the crew of a stricken shuttle, Hubble is not equipped to house astronauts.

In response, NASA altered the rescue plan by positioning the shuttle Endeavour on a second launch pad at the Kennedy Space Centre well ahead of the Hubble mission.

If necessary, Endeavour and a crew of four astronauts could be launched on a six-day rescue flight. Atlantis carries enough provisions for 25 days.

As the damage assessments of Atlantis unfold this week, NASA will continue preparations to launch Endeavour in as few as three days.

"At any time, if they tell us they have damage on Atlantis we will be able to pull the trigger and launch Endeavour," said NASA launch director Mike Leinbach.