- As the search for debris from the stricken shuttle gathered
pace throughout Texas, former astronauts and space experts looked at a
series of possible causes of the disaster that shook America.
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- The main focus is on its age. Built in 1979, Columbia
was the oldest shuttle in the NASA fleet and was on its 28th flight.
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- Although various parts of the craft are continually renewed,
the central structure may have begun to give way as it shuddered through
the upper atmosphere at 12,500 mph.
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- Last night it emerged that the hydraulics system which
powers the shuttle's ailerons (wingflaps) may have failed causing the ship
to bank incorrectly. This would cause huge air pressures on the structure.
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- Former NASA scientist John Quincey told us: "If
the shuttle just gets a little out of alignment, if things aren't absolutely
perfect, the aerodynamic forces literally tear the plane."
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- These are the other vital theories that need investigation:
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- VERTICAL STABILISER: There have been also rumours throughout
the mission that the stabiliser on the shuttle÷situated towards
the tail of the craft÷was faulty. The stabiliser balances the shuttle
as it approaches the Earth's atmosphere. Any error could have led to it
diving too steeply to withstand the heat and pressure of re-entry.
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- MISSING TILES: Dislodged heat-resistant tiles that protect
the ship on re-entry have caused problems throughout the history of shuttle
exploration. Tiles may have fallen off Columbia during launch 17 days ago
when foam thermal insulation on a fuel tank broke free and dented the left
wing of the shuttle.
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- COMPUTER ERROR: A fault in the sophisticated on-board
computer guidance system could have led to the craft re-entering the Earth's
atmosphere at the wrong angle, causing an excessive build-up of heat over
the maximum 3,000 degrees Fahrenheit the underbelly of the shuttle is built
to endure.
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- FUEL LINE FRACTURE: An earlier failure in the fuel system
could have caused a fire that led to a weakness in the craft on re-entry.
It is the least possible of the mechanical causes but sources at NASA have
refused to rule out a link.
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- TERRORISM: The least likely, but fears that the disaster
was an attack swept America at first because of constant fears about al-Qaeda
atrocities÷and the fact that one of the seven who died was Israel's
first astronaut, Ilan Roman,
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- Speculation intensified when TV channel CNN claimed within
hours that he was one of the pilots who helped destroy an Iraqi would-be
nuclear reactor in a pre-emptive strike more than 20 years ago.
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- But White House officials later dismissed links to terrorism
as "unlikely".
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- Former astronaut Jim Lovell÷captain of the aborted
1970 Apollo 13 mission÷believes any investigation into the disaster
will focus on structural, mechanical or computer failure.
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- A further theory emerging late last night was that the
shuttle may have flipped over on re-entry. Engineers say this may have
been caused by a software failure or a sudden burst of power by one of
the engines.
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- Lovell said: "It could certainly have been a fuel
problem or a structural failure caused by the huge vibrations the shuttle
would undergo on re-entry÷or some sort of explosion on board."
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- British scientist Dr Chris Riley, who has flown with
NASA on two astronomy missions to the edge of space, claimed it may have
been a flight too far for what was an old boneshaker in space exploration
terms.
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- The Columbia was NASA's hardest-working shuttle, clocking
up more than 115 MILLION miles.
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- Dr Riley said: "I don't think it's a coincidence
that this was the oldest shuttle in NASA's fleet÷the possibility
of structural weakness is high.
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- "Combine that with hitting the top of the Earth's
atmosphere at 17,500 mph with immense air pressure stresses and you can
see that if it's going to break up it will happen then."
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- Dr Riley, of Imperial College, London, also believes
that a malfunction in the vertical stabiliser on the craft or a failure
in the computer system guiding it down may have caused Columbia to come
in at the wrong angle.
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- "The crew might also have been forced to make a
manual re-entry if the compter went down÷and the slightest error
in trajectory could have been disastrous," he said.
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- "Coming in at too steep an angle might have also
resulted in the sort of break-up of the spacecraft that seems to have happened."
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- TV astronomer Patrick Moore, an authority on space exploration,
put the catastrophe down to the angle of descent.
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- "It is critical that it should have re-entered at
approximately a 30 degree angle. It seems though when looking at the footage
this was not the case. It was way off.
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- "In my opinion, it would appear that this has had
a devastating affect on the body of the shuttle, causing it to break up."
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- Moore last said the tragedy would put space exploration
back years. "Even though they make the most rigorous, detailed scientific
checks things can still go wrong.
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- "This was a routine mission. These things happen.
It's a terrible tragedy."
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- Additional reporting: Sharon Marshall, Matt Acton, Jules
Stenson, Jane Atkinson and Hannah Perry
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- <http://www.newsoftheworld.co.uk/news/news3.html>http://www.newsoftheworld.co.uk/news/news3.html
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