Shuttle Astronauts Complete Flight Checks
SPACE CENTER, Houston – Astronauts completed flight control checks aboard space shuttle Discovery and practiced landing on a computer simulator as they made final preparations to return to Earth.
“It’s time to come home and keep working on getting the shuttle better and ready to fly in the future again,” Commander Eileen Collins said during a series of interviews Sunday.
As the crew prepared for the return trip and Monday arrival, the seven astronauts got good news from Mission Control: For the first time in three years, all four gyroscopes that control the orientation of the international space station were working.
Discovery’s astronauts spent nine days of their 13-day mission resupplying the orbiting lab and two spacewalking astronauts replaced a gyroscope, which stopped working in 2002. They also restored power to another gyroscope, which stopped spinning in March.
The station’s crew waited until Discovery undocked to rev up all four gyroscopes at once.
“There’s lots of cheering on board Discovery right now,” Collins radioed back to the ground.
While on orbit, Discovery’s crew unloaded the station’s trash, conducted intense inspections of their shuttle for damage and tested repair techniques developed after the 2003 Columbia tragedy.
During an unprecedented spacewalk to repair the ship, astronaut Stephen Robinson pulled two strips of protruding tile filler from beneath Discovery’s belly. Engineers on the ground had worried if the strips weren’t removed, they could cause dangerous overheating during re-entry and lead to repeat of Columbia’s disastrous descent, based on a hole pierced by a piece of foam in that ship’s left wing during launch.
“It’s been an outstandingly successful mission,” deputy shuttle program manager Wayne Hale said of Discovery. “We accomplished everything that we set out to do and more.”
However, the daunting, suspenseful and dangerous task of getting Discovery home remained.
Discovery’s pilot Jim Kelly said he has no concerns about landing and likened a shuttle during descent to a runaway freight train.
“That’s a little bit what it feels like – a very exciting, exhilarating process that ends with being at home,” he said.
On July 26, Discovery became the first shuttle to return to space since Columbia, disintegrated after the searing gases of re-entry melted its wounded wing. All seven Columbia astronauts died.
“Flying a re-entry from 17,500 miles per hour to stop in this 100-ton glider that has got one shot at a runway is not what normal, sane people would normally call safe,” Hale said.
Flight director Paul Hill described a returning shuttle as a hurling brick that must become aerodynamic and hit the runway just right.
“You only get one shot at it since we are just a great big lighter,” he said.
David Wolf, an astronaut who heads NASA’s spacewalking branch, said as the shuttle returns to Earth through a fire cloud “you can look out the upper window and it is almost like a tornado of fire behind you.”
“A lot is going on,” he said. “It has never seemed like entry was a done deal or an easy event.”
Columbia’s 85,000 pounds of wreckage rained across Texas and Louisiana in early 2003 during a cross-country descent.
As a result, Discovery will bypass most of the United States on landing day. It will approach Florida from the southwest after flying over Nicaragua, Cuba and on into Cape Canaveral.
Weather looked favorable for a Monday landing but if the forecast changes and Discovery has to land in California, Hale said the space agency will adjust the spaceship’s course to avoid flying over Los Angeles.
NASA has suspended future launches until it finds another foam fix for the external tanks that fuel the shuttle’s climb to orbit.
A 1-pound chunk of foam insulation – reminiscent of the one that doomed Columbia – ripped from the Discovery’s external tank shortly after liftoff. Unlike Columbia, the foam missed Discovery.
NASA has already spent $1.4 billion and 2 1/2-years working on the problem and says more work is needed.
Hale said 47 items “great or small” will be considered and rectified by mission managers before the next launch. Among them: the thermal-tile fillers that came loose from Discovery’s belly and a torn thermal blanket under a cockpit window, which engineers concluded had only a remote chance of coming loose during re-entry.
“We are going to be pretty darn happy to get to wheels stop and see this good crew step off Discovery,” Hill said. “We all are going to feel a huge sense of accomplishment having gotten through the last 2 1/2 years and demonstrated that we still know how to do this very difficult and dangerous business.”
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On the Net:
NASA: http://www.nasa.gov/returntoflight/main/index.html