Tuesday, March 25, 2008

Endeavor undocks, heads home

Re-entry wednesday night
The US space shuttle Endeavour began its trek home to Earth Monday after a record five successful spacewalks and 12 days at the International Space Station where astronauts installed Japan's maiden ISS laboratory.

With the installation Japan gained a foothold on the orbital outpost alongside the United States, Russia and Europe, whose laboratory Columbus was delivered to the station in February.

"Endeavour, we have physical separation" of the two crafts, a NASA official said on a live US space agency broadcast of the undocking that took place some 211 miles (340 kilometers) above the Indian Ocean.

Departure of the shuttle and its seven-member crew was delayed 29 minutes to 8:25 pm EDT (0025 GMT Tuesday) following "minor tweaking" to a faulty solar panel latching device, NASA said.

The device, known as a Beta Gimbal Assembly, lets solar wings on the space station tilt along an axis toward the sun to maximize solar energy use, but the assembly on the station's main portside truss did not close correctly and needed to be reset.

After separation, shuttle co-pilot Gregory Johnson took the shuttle on a slow-motion flyaround of the ISS to allow astronauts to document exterior conditions of the station before heading back to Earth.

Endeavour commander Dominic Gorie late Sunday described the 16-day mission as an all-around success.

"We've done awesome," Gorie said.

"Every spacewalk was a win, every robotic op (operation) was a win. We've got a couple more to go with the undocking and the landing, but we've got a great winning team."

The shuttle is scheduled to return to Kennedy Space Center, Florida on Wednesday.

Two astronauts from Endeavour -- mission specialists Robert Behnken and Mike Foreman -- on Sunday attached a 50-foot sensory boom to the outside of the space station.

ISS flight director Dana Weigel said the spacewalk, often referred to by NASA officials as an EVA, or an extra-vehicular activity, had set a new record.

"This was five EVAs, which was more than we've done on any station mission," Weigel said.

Endeavour launched on March 11. Its mission at the ISS is the longest ever.

The spacewalkers also successfully installed an experiment on the outside of the European Space Agency's laboratory, which the astronauts had failed to complete during the third spacewalk on March 17.

The Endeavour mission's main tasks were to install the first part of the Japanese Kibo lab, a micro-gravity research facility that will be the station's largest module when completed in March 2009.

"At this moment, the people of Japan are very excited about the module," said Japan Aerospace Exploration Agency astronaut Takao Doi, who is to return to Earth on board Endeavour. "It is going to open up a new era for Japan in the space program."

He added that it remained to be seen how Japanese culture would adjust to the realities of ISS.

But in the meantime, "we like the food a lot," quipped space station commander Peggy Whitson.

European Space Agency astronaut Leopold Eyharts of France, who is returning to Earth after about two months aboard the ISS, said he was ready for the trip back home.

"I'm trying to exercise regularly, but I'm quite confident because a couple of months is not so much," Eyharts told reporters.

Astronauts also tested new repair techniques for the shuttle's heat shield. NASA has been testing different in-space repair techniques on the shuttle's protective layer since a crack in Columbia's heat shield caused it to explode while re-entering Earth's atmosphere in 2003, killing its seven-member crew.

Astronauts have also assembled the Canadian-made Dextre robot, which is designed to undertake maintenance operations on the space station that until now required a human touch, and reduce the need for risky spacewalks.

The robot's human-like upper torso swivels at the waist, and its arms were designed with seven joints to provide it with maximum versatility. Umbilical connectors provide power and data connectivity.

Manipulated by joysticks inside the ISS or from ground control on Earth, the 1.56-tonne Dextre will conduct operations such as replacing small components on the station's exterior.

NASA wants to complete construction of the ISS by 2010, when its three-shuttle fleet is scheduled to be retired.

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