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BRITAIN PLANS 25m SHIELD TO PREVENT ASTEROID COLLISIONS

From The Sunday Times, 17 September 2000
http://www.sunday-times.co.uk

By Jonathan Leake, Science Editor
 
A GOVERNMENT team is to propose spending up to 25m on a plan that would
safeguard Britain and the world from devastation by a giant asteroid or
comet.

The Spaceguard initiative, expected to be announced tomorrow by Lord
Sainsbury of Turville, the science minister, could see Britain using a
chain of telescopes to detect and monitor "near-Earth objects".

A report, from a commission appointed by Sainsbury, says that Earth
faces a tiny but definite risk of being struck one day by an asteroid -
a large lump of stone or metals travelling at tens of miles a second.
This kind of impact is believed to have wiped out the dinosaurs 65m
years ago.

A monitoring station, possibly based at Armagh in Northern Ireland and
linked to telescopes around the world, would be the first stage in a
programme that would also investigate ways of knocking any approaching
asteroid off a collision course with Earth.

One option could be to fire a nuclear missile that would explode close
to the incoming rock and deflect it.

At least two big impacts were recorded during the last century alone.
The first, at Tunguska in Siberia in 1908, devastated an area the size
of greater London. The other, in Brazil in 1947, left several huge
craters. Both fell in unpopulated areas and nobody was killed.

Last week astronomers announced that a huge asteroid would cross Earth's
orbit today at a range of 2.6m miles. In astronomical terms this is a
tiny distance - and others will come much closer.

In 2027, a rock measuring half a mile in diameter, travelling at 50
miles per second and known as 1999 AN10, will hurtle past Earth at a
distance of just 200,000 miles. It will pass close by several more times
- with nobody yet able to predict whether it will hit the planet.

The British commission includes Professor Harry Atkinson, who has worked
for the European Space Agency and other international bodies, and Sir
Crispin Tickell, the former British ambassador to the United Nations. It
was set up in January.

The threat is already taken seriously by America and Japan, which have
established their own Spaceguard projects. Nasa has said it plans by
2006 to track all asteroids with diameters greater than 1km that will
cross the path of Earth.

An asteroid that size would wipe out most life and there would have been
many such events early in Earth's 4.6 billion-year history. Now,
however, the risk is much lower because most potential collisions have
already happened. The last big asteroid, about six miles in diameter,
was the one that wiped out the dinosaurs.

The commission's report says Britain's role could be to find smaller
objects, between 50 yards and about half a mile in diameter, of which
there are many thousands.

Up to six telescopes would have to be built - some designed to detect
near-Earth objects, others to track them continually and a third group
to analyse the light they reflect in order to find out what they are
made of.

The aim of Spaceguard would be to ensure that Earth had sufficient
advance warning - hopefully decades - to investigate and then take
preventive action.

A Whitehall source said: "We accept there is a risk and want Britain to
take a leading role in dealing with it."

Sainsbury wants other European countries to help finance the network,
which would be computerised and would enable astronomers to build up a
huge database from which they could predict which objects presented a
threat.

Mark Bailey, director of the Armagh Observatory, a world-renowned centre
for the study of asteroids and comets, where the project would probably
be based, believes the world is now so heavily populated that even a
small impact could kill millions. "Asteroid and comet impacts have
changed human history in the past and it could happen again," he said.

The biggest risk to Earth is from comets that appear at random from the
Oort Cloud - a huge sphere of icy rubble that surrounds the solar
system. They move very fast and could reach Earth within months of being
spotted.

Dr Bill Napier, an astronomer who specialises in comets and asteroids,
believes the only solution is to set up a fleet of rockets carrying
nuclear bombs that could be detonated half a mile from any threatening
object.

"You would only have to nudge them a few metres to send them safely past
Earth to avoid Armageddon," he said.

Copyright 2000, Times Newspapers Ltd.

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