Shuttle Landing on Wed

The space shuttle Atlantis, after successfully delivering a major new section to the International Space Station, glided home for a safe landing at the Kennedy Space Center on Wednesday, announcing its arrival with twin sonic booms just before touchdown.
Ending a challenging 13-day mission, Atlantis and a crew of seven took advantage of favorable weather to return to Florida and clear the way for a military attempt to bring down a failed spy satellite.

Atlantis landed at Kennedy at 9:07 a.m. Eastern time, and did not need to make use of the backup landing strip at Edwards Air Force Base in California. Kennedy is the preferred touchdown site for space shuttles, sparing NASA the time and expense needed to ferry the orbiters across the country after missions, but stormy weather has sometimes gotten in the way.

NASA usually does not activate the Edwards site for shuttle landings unless conditions at Kennedy prove very unfavorable, but it took the unusual action of readying both sites this time, to assure that the shuttle was on the ground by Wednesday evening so that the military could proceed with its plans.

The Pentagon intends to fire a missile from a Navy ship to destroy the satellite, which is out of control and expected to crash to Earth early next month. The satellite, which failed soon after launch in December 2006, is carrying a half-ton of frozen hydrazine rocket fuel that could harm people if it crashes in a populated area, the Pentagon said. The attempt to destroy it could come any time this week, and possibly as early as Wednesday, according to military spokesmen.

Because Atlantis potentially could have been damaged by space debris from hitting the satellite during its descent from orbit, NASA and military officials wanted the shuttle to land before the military operation was attempted.

Bryan Lunney, the flight director for the shuttle landing, said on Tuesday that NASA was not pressured by the Defense Department to hurry the landing, and that Atlantis would have remained in space longer if the conditions for a safe landing were not met Wednesday.

Atlantis departed from the space station on Monday and the shuttle was cleared for landing after an inspection of its heat protection tiles showed that everything was normal.

The only technical issue that arose was failure of a heating system circuit that disabled four small aft thrusters.

These jets were not needed for re-entry, Mr. Lunney said, but rather to prevent any fuel-line damage that could delay Atlantis’s next flight.

Atlantis’s mission, which was delayed for two months because of a recurring problem with malfunctioning fuel tank sensors, mostly went according to plan.

The primary objective of the flight was adding the European Space Agency’s Columbus laboratory module to the orbiting space station. The laboratory, crammed with scientific equipment, is Europe’s main contribution to the international project.

The 17 nations who are members of the agency invested about $2 billion in the project in all, including the cost of the module, its equipment and experiments, and a control center located outside Munich, Germany.

Columbus, a pressurized unit 23 feet long, 15 feet in diameter and weighing 22,700 pounds, significantly increases the space station’s research capability and gives Europeans a major role in human spaceflight. It was built in Italy and outfitted in Germany.

The only major hitch in the mission came when Hans Schlegel, a European Space Agency astronaut from Germany who was to participate in two of the mission’s three spacewalks, suffered an unexplained medical problem. Mission managers delayed the first spacewalk, to install Columbus, by a day and substituted NASA astronaut Stanley G. Love for Mr. Schlegel.

Mr. Schlegel recovered to perform his other assigned spacewalk.

Atlantis also carried a new crewman for the space station. The crewman, Gen. Leopold Eyharts, a French Air Force general, replaced Daniel M. Tani as a member of the station crew. General Eyharts’ assignment is to finish setting up and testing Columbus, and to get its racks of experimental equipment ready for full operation.

Mr. Tani served on the station two months longer than planned because of Atlantis’ delayed flight. While in space, his mother died in a Dec. 19 car accident.

During an emotional farewell gathering before leaving the station, Mr. Tani dedicated his stay to the women in his life, including the 90-year-old mother he called “my inspiration.”

“And of course, my job is easy compared to my wife’s,” he said. “Jane’s the love of my life, and she had the hard work while I was having fun. So I can’t wait to get back to her and my two little girls.”

During the mission, the Atlantis astronauts also attached two large experiment packages to the outside of Columbus and retrieved a failed gyroscope unit from outside the station to return to earth for refurbishing. They also replaced a refrigerator-sized tank of nitrogen that pressurizes the station’s ammonia cooling system and loaded the spent unit into the shuttle to return to Earth.

The astronauts also transferred almost 1,300 pounds of supplies and equipment from the shuttle to the space station, and are bringing back about an equal amount of equipment and scientific samples from the station.

Atlantis will spend months on the ground being prepared for its next flight, scheduled for August, which will be the last mission to send astronauts to repair and upgrade the Hubble Space Telescope.

http://www.nytimes.com/2008/02/20/science/space/20cnd-shuttle.html?ref=science

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