Astronauts stow stubborn solar array (AFP)

19.12.2006 04:02 Space - Source: Yahoo space

HOUSTON, United States (AFP) - Two astronauts finally unstuck a balky solar array on the International Space station, folding the panel into its box during a special space walk.

"The solar array has been fully retracted," Nicole Cloutier, the official commentator on NASA television said to applause at mission control here.

After a record-breaking fourth space walk on a single mission, US astronaut Robert Curbeam, together with Sweden's Christer Fuglesang, returned to the ISS at 0138 GMT after a space walk that lasted more than six and a half hours.

The walk, for which NASA has lengthened the Discovery mission by a day, followed several days of attempts to shake loose the array, which supplies power to the ISS but has been replaced with new solar panel assemblies.

Besides shaking, tugging and pushing on the array from inside and outside the ISS, on Friday NASA engineers in Houston asked German astronaut Thomas Reiter to exercise vigorously for 30 seconds on the ISS's training machine, hoping his vibrations would loosen the stuck array panels.

Reiter, who is at the end of a five-month stay on the ISS, tried several times to shake the array into action but was unsuccessful.

On a space walk Saturday, the astronauts completed a delicate rewiring of the space station but were again unable to fix the jammed array. That led to a decision to add one more walk to the schedule, and to extend the entire Discovery mission by one day.

The decision to delay the landing originally planned for Thursday would halve the shuttle's two-day safety cushion for return to Earth.

Discovery will only have one day's supply of oxygen and electrical power left, requiring a landing by Saturday at the latest.

During Monday's space walk, Curbeam and Fuglesang, who represents the European Space Agency on the mission, had several tools at their disposal, including a scraper and a hook for the wire that guides the folding of the array, which powers the ISS.

The astronauts were authorized to pull guide wires, push panel hinges and, if necessary, shake the array to free it.

The mission marked the first-ever space walks on consecutive days. There was little opportunity to enjoy the spectacular view of Earth, as the astronauts faced the threat of their space suits being pierced with micro-meteorites.

They also had to be extremely careful not to damage the sensitive panels.

The panel was folded away as a new set of solar panels were activated to tap the sun's rays for electricity for the space station.

The station, when completed, will have a total of four solar arrays providing it with electricity.

Including the current Discovery mission, NASA has planned 14 shuttle flights to complete the ISS by 2010, when the shuttle fleet, down to three vehicles, is to be retired.

Discovery and its seven-member crew blasted off last Saturday from Cape Canaveral, Florida, in the first nighttime liftoff in four years.