Averting armageddon: how to stop an asteroid
Pastor Dale Morgan
Averting armageddon: how to stop an asteroid*
Hollywood got it wrong, this is how you stop an apocalyptic asteroid
Richard Gray, Science Correspondent, Sunday Telegraph
Last Updated: 12:30am GMT 25/02/2007
Attempts to save mankind by smashing asteroids as they head towards
Earth may do more harm than good, scientists believe.
Rather than Hollywood's preferred option, engineers are trying to
develop unmanned rockets that can land on space rocks and use the
asteroids' own material to propel them into a safer orbit.
The plan will be detailed at a conference, sponsored by Nasa next month,
at which its scientists will reveal their -estimate that 100,000
asteroids orbiting near Earth are large enough to destroy a city. So far
the agency has only been able to identify and track 4,000 of them.
Just one football pitch-sized asteroid smashing into the planet would
create destruction on a terrifying scale, wiping out any area it hit,
sending flaming debris into the atmosphere and causing tidal waves.
Scientists claim that it is only a matter of time before one is found on
a collision course.
Research to be unveiled at the three-day Planetary Defence Conference in
Washington DC will reveal that defending the Earth may not be as simple
as suggested by films such as Armageddon in which Bruce Willis's
character destroys a giant asteroid using a nuclear bomb.
Gianmarco Radice of Glasgow University will be one of more than 200
scientists at the conference. He said: "A nuclear blast may cause it to
fragment. So instead of having one large object on an impact course, you
have five largish objects.
"Also, we do not know a huge amount about the composition of these
asteroids. Some are made of rock, others are ice while others are just
piles of rubble. If you smash something into a pile of rubble, it will
just break up and then reform by gravity."
Nasa has already tested the approach by smashing a spacecraft into an
asteroid in its Deep Impact mission last year. The European Space Agency
is planning a similar test, sending a craft to smash into a 500-yard
wide asteroid while another spacecraft -monitors the results.
Now an engineering firm in Atlanta, Georgia, has been commissioned by
Nasa to develop a new kind of mission to land on an asteroid, drill
through the surface and pump the debris into space. Anchoring several
unmanned spacecraft, nicknamed Madmen, to an asteroid and ejecting
material, would produce enough force in the opposite direction to push
an asteroid slowly off its dangerous course.
"It is like throwing rocks out of a rowing boat on a lake. The rocks go
in one direction and the boat is slowly pushed in the other under the
laws of physics," said John Olds, the chief executive of SpaceWorks, the
firm behind the scheme. "Over several months we think we can make the
difference between a hit and a miss." Astronomers fear that a 400-yard
wide asteroid will pass dangerously close to the Earth within 30 years.
Typically, one the size of a football pitch strikes every 100 years or
so, and it is also almost 100 years since the last major impact which
caused an explosion equivalent to a 15 megaton nuclear bomb in Tunguska,
Siberia on June 30, 1908.
Fears were heightened in 2004 by the discovery of a 45 million-ton rock
orbiting the Sun called Apophis, which will pass just 22,000 miles from
the Earth in April 2029. In 2036, it will have a close encounter. Some
scientists calculate it may even hit the planet.
Nasa believes that it has managed to identify nearly 90 per cent of all
asteroids larger than 1,000 yards. These are capable of causing a
-global disaster, throwing huge amounts of debris into the air and have
historically caused widespread extinction.