September 20, 2008

NASA Readies Endeavor As Hubble Mission Backup

In an unparalleled move, NASA rolled its space shuttle Endeavour on to a spare launch pad at the Kennedy Space Center on Friday in case it is needed to rescue a stranded Hubble Space Telescope servicing crew.

Endeavor is scheduled for an International Space Station (ISS) construction mission in November, but will serve as a standby for next month's Hubble Space Telescope mission, which will be carried out by the space shuttle Atlantis.

Atlantis and its 7-member crew will make the trip to space for a final repair job on the 18-year-old Hubble Space Telescope. The mission was initially considered too dangerous, and was cancelled a few years ago.  NASA feared that should Atlantis suffer serious damage during launch or in flight, the astronauts would not be at the international space station to safely await a ride home.  Instead, they would be stranded on their spacecraft at the Hubble, where they could stay alive for just 25 days before losing air.

Under the rescue scenario, Endeavour and four additional astronauts would need to lift off as soon as NASA determined Atlantis was unable to return home.

To prepare for such a mission, Endeavour was parked at its launch pad a mile away from where Atlantis is tentatively set to launch on Oct. 10.  It is the first time since 2001, and likely the last, that both of NASA's shuttle pads are now occupied. 

Astronauts for the Atlantis mission say there's only a small chance such a rescue mission would be needed, and that they would fly to Hubble even without a backup plan.

Scott Altman, Atlantis' commander, acknowledged that the backup plan is the right thing to do, even though it might seem like overkill.  

"It's kind of a belt-and-suspenders approach. But if you need the belt after your suspenders fail, you would be glad you had it," Altman, a retired Navy captain and former fighter pilot, told the Associated Press.

In addition to the usual risks that accompany launch and landing, the Atlantis crew faces an estimated 1-in-185 chance that a micrometeoroid or a piece of space junk will inflict catastrophic damage to their craft.

The increased risks result from Hubble's very high and debris-littered orbit.  As with other missions, the crew will inspect their spacecraft in orbit for signs of damage during approach and departure to the Hubble. 

NASA has enacted rescue plans in case of irreparable damage ever since the craft's resumed flying following the 2003 Columbia tragedy that killed seven astronauts.  However, all those missions have been to the space station, where astronauts could take refuge for two months if need be.

But the Hubble mission offers no such luxury, which is why the Hubble repair mission was canceled in 2004.  At that time, NASA's boss determined it was too dangerous.

A new NASA regime later reversed the decision under the condition that another shuttle would be on the ready at the launch pad, something never before attempted.

NASA made a similar move in 1973 during the initial space station program, Skylab, but a rescue was never needed.

Once Atlantis is in flight, "if it even begins to smell" like a rescue might be required, NASA will begin final preparations for Endeavour to lift off, according to launch director Mike Leinbach, who said Endeavour could launch within six days.

Should a rescue mission take place, Endeavour would fly to Atlantis and then use a 50-foot robotic arm to grab the damaged shuttle. Atlantis astronauts would wear special spacesuits to "float" to Endeavour a few at a time during three separate spacewalks. Endeavour would then return to Earth with all 11 astronauts on board.

Officials say the most difficult decision would be determining if Atlantis had suffered serious enough damage to warrant a rescue mission. Atlantis would then be sent into the Pacific once its astronauts were safely aboard Endeavour.

"This will be an emotional thing," Leinbach told the AP.

Such a mission would potentially endanger four more astronauts and would spell the end of Atlantis, and likely the entire space shuttle program, planned to be phased out in 2010.

It would be on par with the drama of Apollo 13, said Atlantis' launch director Ed Mango.

Leinbach would lead the rescue launch, which would be the most important thing the space administration has ever done.

Altman acknowledged that storms or a last-second engine shutdown could potentially keep Endeavour grounded, preventing a rescue mission.

"There's no guarantee it would get there," Altman said in an interview with The Associated Press.

"On the other hand, you look at how many things would have to go wrong to make it not possible to pull off. ...

"There's a scenario out there that doesn't have a happy ending, and I think we all have to come to grips with that before launch."

The Houston center, home to NASA's Mission Control and the main training facility for astronauts and flight controllers, was closed amid flooding and widespread power outages caused by Hurricane Ike.  It will likely not reopen until Monday.  

During its Hubble repair mission, Atlantis will carry two new science instruments, gyroscopes, replacement batteries and repair kits to fix two of its cameras.

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