Discovery astronauts attach truss to space station in first walk (AFP)

13.12.2006 04:30 Space - Source: Yahoo space

HOUSTON, United States (AFP) - Two astronauts from the space shuttle Discovery have completed the hook up of a huge truss to the

International Space Station during the first of three space walks that aim to extend and rewire the orbiting research craft.

Mission specialist Robert Curbeam and Sweden's first astronaut Christer Fuglesang spent six hours and 36 minutes in the void of space attaching the two-tonne truss segment to the ISS among other tasks, NASA said.

"Christer, you knocked yourself out," mission control told Fuglesang. "Congratulations."

"From here on the ground, we'd like to send our congratulations for a 100 percent successful first EVA," said astronaut Steve Robinson, also speaking from mission control and referring to extra-vehicular activity -- jargon for space walk.

The space walk ended at 0307 GMT Wednesday as the station orbited over north Africa.

The operation was particularly sensitive because the astronauts had to move the truss within centimeters (inches) of the fragile solar arrays that provide electricity to the orbiting laboratory.

In a delicate maneuver, the 3.37-meter (11-foot) truss was guided by the ISS robotic arm operated by US astronaut Joan Higginbotham in coordination with Curbeam and Fuglesang, who bolted the structure in place.

Discovery co-pilot Bill Oefelein directed the heavy construction work that extended the station's total length to 120 meters (394 feet).

Curbeam and Fuglesang also attached six cables on the space station for electricity, communications and climate control.

Last on their worksheet were maneuvers to allow enough room for the new solar arrays to track the sun's rays in a 360-degree rotation.

"It was a very successful flight and space walk," said Space Station flight director John Curry, speaking in Houston after the space walk. "We met all of the major objectives," he said.

The girder-like space station structure is being assembled piece by piece. Construction resumed in September with the Atlantis mission, after a three-year hiatus following the 2003 Columbia disaster.

Two other space walks, scheduled on Thursday and Saturday, are expected to be highly complex. The astronauts are tasked with rewiring the electricity and climate control of the US-made portion of the ISS from its present, temporary set-up.

The work, during which power to half of the ISS will be switched off, includes activating the solar arrays installed by an Atlantis mission in September that will double the station's present electrical output.

Curbeam and Fuglesang will work on the ISS on Thursday, and on Saturday Curbeam and mission specialist Sunita Williams will install cameras outside the ISS expected to greatly facilitate future construction work.

The Discovery mission is part of 14 shuttle flights NASA has planned over the next four years to finish the ISS by 2010, when the shuttle fleet, down to three vehicles, is to be retired.

Discovery blasted off late Saturday from Cape Canaveral, Florida -- the first nighttime liftoff in four years -- on its 12-day construction mission to the ISS. It docked on the station Monday and is to remain there eight days.

Williams replaced Thomas Reiter of Germany on the space station, who arrived at the ISS in July on Discovery. Reiter will return to Earth on the same shuttle, scheduled to land on December 21.

In a mission that has gone smoothly so far, National Aeronautics and Space Administration engineers said that Discovery's heat shield had not suffered any damage.

Two preliminary inspections carried out after takeoff and shortly before Discovery docked with the ISS had shown no damage.

Such inspections on the shuttles have become routine since the Columbia tragedy.

Columbia's heat shield was pierced by foam insulation that peeled off its fuel tank during liftoff, causing the shuttle to disintegrate during its return to Earth in February 1, 2003, killing all seven astronauts on board.