New danger for shuttle return

[Guest Glenn]

Source: The Australian

 

Robert Lusetich, Los Angeles correspondent

 

August 02, 2005

 

NASA engineers will decide today whether a risky space walk is needed to repair a new problem with the shuttle Discovery - another setback to an already tarnished return to space.

 

After a nerve-racking first week in orbit, when it was thought debris that hit the Discovery during lift-off might endanger the safe return of its seven astronauts, a second potential danger threatening next Monday's return to Earth was identified yesterday.

 

Two strips of so-called "gap fillers" are protruding in a vulnerable position on the orbiter's underbelly.

 

Gap fillers, made of heat-resistant alumina-borosilicate fibre, fill the space between the shuttle's tiles when they expand and contract due to extreme temperature fluctuations.

 

They have protruded during prior missions, but aerodynamicists at NASA cannot agree on whether these two pieces of cloth - about two and three centimetres long, respectively - will have an effect on the shuttle's ability to withstand the heat of re-entry, when temperatures reach 1260C.

 

There are no conditions on Earth that can replicate an object travelling at 18 times the speed of sound, as the shuttle does, and so scientists are left with educated guesses, which in turn have led to "strong disagreements" at NASA, according to Wayne Hale, the mission's deputy program manager.

 

"Tonight they're working overtime trying to compress, I believe the phrase was, a decade's worth of study into two days," Mr Hale said.

 

Debris that hit the Columbia in 2003 soon after lift-off damaged the orbiter's heat shield, causing the shuttle to disintegrate during the searing heat of re-entry. All of the seven astronauts aboard Columbia were killed.

 

While Mr Hale did not downplay the potential danger of the protrusions, which he admitted he thought last week would be "no big deal", he confidently dismissed parallels between this new problem and what went wrong with Columbia.

 

"The difference between before Columbia and today is night and day," he said.

 

Experts were working around the clock to decide whether the protrusions need to be cut off - using pliers, scissors or a small saw - by astronauts in a space walk, a task never tried before.

 

A secondary danger is that space-walking so close to the orbiter opens the possibility of damaging the shuttle.

 

"The risk here of going underneath the vehicle is, we hope, relatively remote," Mr Hale said.

 

"But it is surely something you have to think about. That is part of the calculation.

 

"We do repairs and maintenance on the space station all the time, on the Hubble space telescope and on satellites.

 

"However, I don't recall ever doing anything like this on the orbiter itself."

 

Australian astronaut Andy Thomas, aboard the Discovery on his fourth space mission, gave a video-linked interview yesterday during which he expressed disappointment in NASA.

 

Like many, Dr Thomas seemed astounded that NASA - which spent $US1billion ($1.32billion) and took 2 1/2 years to ensure the safety of shuttles after the Columbia tragedy - had not developed a way to stop foam falling off the external fuel tanks.

 

This extraordinary failure has grounded the shuttles until a solution is found.

 

It was just such debris that led to Columbia's destruction.

 

Discovery was hit in a similar fashion, though the piece of foam in this case has not seriously damaged the orbiter.

 

Mr Hale admitted that NASA had "goofed" in overlooking the foam issue.

 

"Was there a sound technical reason why they made that decision or was it subject to cost pressures or schedule pressures?" asked Dr Thomas, who had been deputy chief of the NASA's astronaut office before being assigned to this final mission into space.

 

"I think we do need to address the question of why that area was not examined.

 

"It's an emotional disappointment. It's also an engineering disappointment."

 

Discovery commander Eileen Collins also expressed surprise that the foam had been dislodged, but remained optimistic about a safe return.

 

"There are 2 million other parts on the space shuttle that are working perfectly right now," she said.

 

"And we have confidence in that and we know the shuttle is going to get us home."

 

NASA has yet to determine when the shuttle will return, but two possible landing times - back at Cape Canaveral in Florida - are 6.37pm or 8.12pm AEST next Monday.

 

 

[Guest Ultralights]

i hope they have a video feed of the repairs! there would be some great imagry to be taken there!!

 

 

[Guest Glenn]

NASA's return to flight site has some great archived footage and there is a link to NASA TV so more than likely they will show it live when and if it happens. You can find the site here :arrow: http://spaceflight.nasa.gov/home/index.html and :arrow: http://www.nasa.gov/returntoflight/main/index.html