Space station to get final solar panels

ByABC News
March 18, 2009, 8:59 PM

WASHINGTON -- The final set of solar panels will be added Thursday to the International Space Station — a mission that has proven problematic in the past.

The station gets its power from three existing sets of solar panels, which have been an endless source of grief to NASA. Panels have stuck, ripped and crumpled during installation.

If all goes as planned, two astronauts — both paying a visit to the station aboard space shuttle Discovery — will bolt the $300 million set of panels onto the station Thursday during a 6½-hour spacewalk. The panels are scheduled to be unfurled Friday, although NASA may postpone it until Sunday if the astronauts need to do an additional inspection of the shuttle's heat shield.

NASA officials are already steeling themselves for the process to go awry.

"I'm hoping this one will be just a normal … everyday" procedure, station chief Michael Suffredini said before the panel work began. "Of course it won't turn out that way, but I can always hope."

On Wednesday, astronauts John Phillips and Sandra Magnus deftly piloted the station's robotic arm to pluck the solar panels out of the shuttle's cargo hold. Thursday, astronauts Steven Swanson and Richard Arnold are scheduled to secure the solar panels into place at the end of one of the station's beams.

The most nail-biting work is likely to come Friday, when Mission Control and the astronauts will try to unfurl the panels.

The panels are each 115 feet long, but for their journey into orbit on the shuttle they were tightly folded into storage boxes. Unfolding them from their boxes has sometimes gone badly:

• In December 2000, when one of the first major panels was unrolled, its cables popped off their pulleys. Astronauts on a spacewalk made an emergency repair.

• In December 2006, spacewalkers had to coax a panel back into its box so it could be relocated. When that panel was unrolled again in October 2007, it ripped and required a dangerous repair by a spacewalker working close to the electricity-laden panels.