Space Shuttle Preps for Station Visit

With just 16 missions on the books until the shuttle program ends, NASA is prepared to resume construction of the International Space Station after a six-month hiatus in shuttle flights. The launch of space shuttle Atlantis, originally planned for March, is now targeted for liftoff at 7:38 p.m. EDT on Friday. Forecasters were predicting an 80 percent chance that the weather would allow the shuttle to launch on time.

The mission was delayed to allow time to repair the shuttle's fuel tank, which was blasted by hail during a freak storm in late February.

"After many months of hard work, Atlantis is finally ready to fly," said Stephen Payne, a shuttle launch manager at NASA's Kennedy Space Center in Florida.

The hailstorm left Atlantis' tank with more than 4,200 dings, dents, gouges and pits in its foam insulation, which is needed to prevent ice formation after the tank is filled with cryogenic propellants for launch. Ice could break off and damage the shuttle's heat shield during launch.

As NASA learned after the fatal 2003 Columbia accident, the foam itself presents a potentially deadly hazard as well. The shuttle was destroyed when superheated gases blasted inside the structure as the ship flew through the atmosphere for landing.

The heat shield had been broken during launch by a piece of foam insulation that fell off and hit the ship's wing. The accident claimed the lives of all seven crewmembers aboard.

Lessons Learned

Mindful of Columbia's demise, NASA set about repairing Atlantis' damaged tank, which ultimately entailed flying workers from the tank manufacturing complex outside New Orleans to Florida, to hand-spray a section of foam near the top of the tank. That area, which is exposed to the elements as the shuttle sits on the launch pad, was most heavily damaged by the hail.

Engineers took extra precautions to test repair techniques before fixing the tank, which managers say has only a slightly higher risk of foam loss during launch than an unblemished tank.
"All our testing today indicates that will not happen," said shuttle program manager Wayne Hale.
NASA can't afford too many more lengthy delays. The shuttle fleet was returned to flight after the Columbia accident for the sole purpose of finishing construction of the space station, which is about half-built.

At least 13 missions are needed to haul the rest of the major components to the outpost, and managers would also like to fly two missions with spare parts and supplies before the fleet is retired in 2010.

A final servicing call to the Hubble Space Telescope completes the shuttle program's flight schedule.
All Eyes on Atlantis
Despite the three-month postponement in Atlantis' flight, managers say there is ample time to complete the station before the shuttles stop flying.

"We're flying these flights as rapidly as it's reasonably possible to do it, but we fully intend to keep all of our safety practices in place," Hale said. "We cannot let schedule drive us to do something dumb."
Atlantis' mission is key to preparing the orbital complex for the arrival of partner laboratories built by Europe and Japan that have been awaiting rides to orbit for years. The shuttle will deliver a new set of power-producing solar wings and a rotary joint so they can track the sun.

The crew also needs to retract an older solar panel that will be moved to another part of the station next year.

The last shuttle crew in December faced similar tasks and encountered major problems folding up the array. Two astronauts made an unplanned spacewalk to painstakingly shake the panel, which repeatedly jammed on guide wires. Ultimately, they were able fold it, accordian-style, into its storage box.

Atlantis' flight is planned for 11 days, but NASA is allowing two contingency days in space to handle unexpected difficulties.

Readying the Crew

The crew is light on previous spaceflight experience, with four of the seven astronauts flying for the first time, but heavy on preparations.

"We've spent a long time training for this mission," said Atlantis commander Frederick Sturckow. "The crew is very excited to be in Florida."

The astronauts arrived on Monday to begin preparations for Friday's liftoff. Meteorologists are predicting an 80 percent chance weather will be suitable for launch.

Joining Sturckow on the flight deck will be pilot Lee Archambault, flight engineer Steven Swanson and astronaut Patrick Forrester. Lead spacewalker James Reilly and astronauts John "Danny" Olivas and Clayton Anderson, who will be seated on the mid-deck for launch, complete the crew.
Sturckow and Reilly have flown twice before and Forrester once.

Anderson will stay aboard the station to replace NASA astronaut Sunita Williams, who has been in orbit since December. She originally was to come home with the next shuttle crew, but with Atlantis' delay, NASA decided to switch ferry flights.

Despite the late start in the shuttle program's 2007 launch calendar, managers hope to complete four flights this year, including a December delivery of Europe's Columbus module.