NASA to scrutinise shuttle shield damage

August 12, 2007 04:53pm

ASTRONAUTS on the International Space Station are set to examine and measure a troublesome gash in the shuttle Endeavour's heat shield, by using a camera and a laser atop a robotic arm.

The 56-square-centimetre gouge near a landing gear hatch was apparently made by a piece of ice that broke off the shuttle's external fuel tank 58 seconds after Wednesday's launch from Cape Canaveral, Florida.

The laser device will provide the exact measurement and depth of the gash so NASA engineers can decide whether repairs are need, for which the Endeavour mission would be prolonged to allow for an additional spacewalk.

Endeavour's mission was initially planned for 11 days, with three space walks.

NASA may extend the mission by three days, and add a space walk, after they test a new system that transfers electricity from the ISS to the orbiter, prolonging the life of the shuttle's batteries.

Separately, if NASA decides that the damaged shuttle tiles need fixing, an additional space walk is possible.

NASA on Saturday studied pictures of the damage taken on Friday, while two astronauts completed the first spacewalk of the shuttle's 11-day mission.

Mission specialists Rick Mastracchio of the United States and Canadian Dave Williams spent six hours, 17 minutes installing and activating a new, 1.58-ton segment for the International Space Station that the Endeavour had delivered.

The two astronauts attached the Starboard 5 truss segment to the Starboard 4 segment, with the help of shuttle pilot Charles Hobaugh, who from inside the ISS operated the station's robot arm holding the 3.37 x 4.24-metre truss.

They also retracted a radiator on the Port 6 truss, which will be moved and attached to the Starboard 5 truss during a future mission, replaced a defective gyroscope on the ISS and installed an external stowage platform.

Back on Earth, meanwhile, National Aeronautics and Space Administration experts analysed 296 pictures of Endeavour's heat shield taken during a routine inspection Friday just before the orbiter docked with the ISS.

In addition to the gash, small white marks were also visible on other thermal tiles surrounding the damaged area, mission manager John Shannon said.

He said NASA was trying to estimate the extent of the apparent damage, which will not be exactly determined until a closer inspection is carried out with the ISS robotic arm bearing a high-resolution camera and laser device.

The ice that caused the damage presumably was formed by humid air coming in contact with the cold surface of the shuttle's fuel tank, which holds super-cold liquid hydrogen fuel for the takeoff and is jettisoned before orbit is reached.

An insulation layer on the tanks is supposed to prevent icing.

The US space agency has carefully inspected the orbiter's protective thermal tiles during each of the missions that have followed the shuttle Columbia disaster of February 2003.

Columbia's crucial protective heat shield was pierced by a piece of insulating foam that peeled off its external fuel tank during liftoff.

The breach resulted in the shuttle disintegrating into a ball of fire as it re-entered Earth's atmosphere, killing all seven astronauts on board.

Endeavour docked on Friday with the ISS bringing seven astronauts, including 55-year-old Barbara Morgan, the first school teacher in space.

Ms Morgan's space mission came 21 years after the shuttle Challenger launch explosion in 1986 killed another woman intended to become the first teacher-astronaut, Christa McAuliffe.

News Limited

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