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- Scientists will urge the government to set up a guard
against destruction from outer space, in an official report to be published
on Monday. A task force will report that collisions with "near earth
objects" such as asteroids and comets are no longer the stuff of science
fiction: they represent a real threat. A collision with one the size of
a small village could wipe out a third of the human race.
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- A 100-metre object crashes into the planet every 10,000
years - triggering a 100 megaton explosion in the air, larger than the
largest H-bomb ever tested. A 1km object scores a direct hit on the planet
every 100,000 years - with the force of 10m Hiroshimas.
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- The near earth objects task force, led by Professor Harry
Atkinson, a scientist who has worked both for the European space agency
and Nasa, was set up in January to consider the growing evidence of danger
and to take advice from astronomers.
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- His report will urge the government to release £20m
for a new telescope in the southern hemisphere to comb the skies, and to
"buy" time on a network of new or existing telescopes in Australia,
Hawaii and the Canary islands to track the solar system's "loose cannons".
The task force - made up of Prof Atkinson, Sir Crispin Tickell, the former
British ambassador to the UN, and Professor David Williams of University
College, London - will also recommend close partnerships with European
and US astronomers to ensure systematic global coverage.
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- The report will suggest support for space-based instruments
to sweep the skies for potential cosmic traffic accidents and British involvement
in European and US satellites which could rendezvous with asteroids far
away and study them more closely. And it is expected to urge a kind of
British "spaceguard" research centre, perhaps at the Armagh observatory
in Northern Ireland, to keep disaster experts, astronomers, media and government
in touch with each other.
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- One problem is that the US - which funds a "minor
planet centre" at Harvard - controls the detailed astronomical information
from observers all over the world. The report could urge that Britain share
some of the cost. "It's an unhealthy state of affairs even if the
US is an ally, when one country controls the information," said one
researcher.
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- Objects from space hit the earth all the time - at speeds
of more than 10 miles a second. Most burn up harmlessly, as shooting stars.
Hundreds have landed as small rocks. There is no record of any human being
killed by a comet or asteroid - but a large one could destroy civilisation.
The aim, the task force report will say, is to detect a potential collision
years or, better still, decades in advance, giving governments of the world
time to take measures.
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- "What they are talking about is setting in motion
ways in which we could really deflect one of these things. That is the
contentious one, because that involves nuclear weapons," said one
astronomer last night. "It doesn't say that, but we know it does.
If you are going to deflect one, you have got to use a nuclear weapon.
There is no other way to do it."
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- This would mean launching a robot spacecraft to meet
an asteroid, and then triggering a precisely calculated explosion which
would knock it off course so that it would miss its date with the earth.
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- Other bodies in the solar system are pock-marked by asteroid
craters. The earth's asteroid scars have been removed by erosion - but
there have been a number of collisions identified by planetary scientists.
The most famous coincided with the death of the dinosaurs 65m years ago,
but a 100-metre object exploded over Siberia in 1908 and wiped out 2,000
sq miles of forest. Two large asteroids have passed alarmingly close to
earth in the last few years. US and French astronomers recently calculated
that 900 asteroids, all 1km across or larger, are whizzing around the solar
system on orbits that cross that of the earth. But Europeans want to start
tracking smaller objects.
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- "A 200-metre object plonking into the Atlantic would
effectively take out all the cities around the seaboards. Those smaller
events occur rather more fre quently - they are talking about a once every
several thousand years event," said Duncan Steel of the University
of Salford, one of the leading authorities on asteroids and comets. "The
report highlights the way in which Britain can make a real contribution
to the international programme - in essence to become No 2 in the world,
behind the US. This would put the UK in a Europe-leading role."
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- Jonathan Tate, a British army officer who several years
ago began pressing for governments to take the threat from space seriously,
is the director of SpaceGuard UK. He argued that a crash from a 1km asteroid
- a one-in-100,000-years event - could kill 25-30% of the human race within
a year. Assuming a UK population of 60m when it happened, that would work
out at an average of 150 deaths a year over that 100,000-year period. One
authority values a human life at £850,000.
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- "That actually works out at £123m a year to
do nothing," he said. "One of the major effects of this report
will be to dispel, for once and for all, the giggle factor associated with
the impact hazard. No sane person can any longer regard this as either
funny or science fiction."
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- Lembit Opik, the Liberal Democrat MP for Montgomeryshire,
has been pushing the government to take the issue seriously for two years.
"If the report confirms a clear and present danger of an impact of
global significance, and that we can do something about it with today's
technology, I shall be happy," he said yesterday.
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- Space invaders
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- A comet is part of the builder's rubble left over from
the making of the planets. Comets live at the far edge of the solar system
and every so often are dislodged into long orbits round the sun , occasionally
crashing into one of the planets in the way.
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- Asteroids - believed to be the fragments of a planet
that never formed - live in a belt between Mars and Jupiter and every
now and then one is tipped into a different flight path.
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- Experts at Cornell University calculate the earth is
at the centre of a network of asteroid "superhighways" and that
a collision is inevitable at some point in the future. They know of 900
asteroids of 1km or more that could smash into the earth. But they calculate
that there could be as many again yet to be detected.
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- Asteroids are believed to be hard, stony, heavy objects
rich in metals. There are commercial plans to "quarry" them in
space and there are several space missions to explore asteroids and comets.
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- Comets are mostly ice and dust and tend to break up under
the gravitational tug of a big planet or the sun. Fascinated astronomers
watched a dozen fragments of Comet Shoemaker-Levy 9 crash one at a time
into Jupiter in 1994.
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- A large asteroid that hit the earth at 10 miles a second
would turn into a fireball, sending sonic booms and shockwaves through
the atmosphere. If it hit solid earth, it would form a crater 10 times
its own size and the shockwave would level brick walls thousands of miles
away. A big one would set the skies alight, and then shower the stratosphere
with dust, blotting out the sun, shutting down all plant growth and condemning
those who survived the shock and fire to death by cold and starvation.
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