On Oct 7, 6:27 pm, "Docrodile" <swampth...@hellsbayou.net> wrote:

Mirror mirror in the sky, save us from asteroids flashing by
FIONA MACLEOD ( fmacl...@scotsman.com)
A NETWORK of mirrors harnessing the destructive power of the sun might
save the world from disaster, space experts believe.

If an asteroid should be discovered on a catastrophic collision course
with our planet, researchers at Glasgow University say mirrors are the
best way to save us from annihilation.

Up to 5,000 could be used to focus sunlight on to the asteroid, melting
the rock and altering its orbital path away from the Earth.

The doomsday scheme was devised after a team at the university compared
nine methods of deflecting near-Earth objects - asteroids and comets.
The
results were unveiled at the Jodrell Bank observatory in Cheshire as
part
of celebrations for the 50th anniversary of the launch of the Soviet
satellite Sputnik 1, which marked the start of the space age.

The research team compared the mirror technique with eight others,
including different types of nuclear explosion and fixing a propulsion
system to the asteroid.

The nuclear options and the mirrors would be more effective than the
others, but scientists fear the risk of flying debris from a nuclear
blast.

The orbiting mirrors would be used to focus sunlight on an area of the
asteroid between 0.5 and 1.5 metres wide, heating the rock to around
2,100C - hot enough to melt the surface of the asteroid and create a
thrust which would nudge it off course.

The team found that the orbit of an asteroid measuring 150 metres
across
could be sufficiently modified by a network of 100 mirrors in a few
days.
For an asteroid the size of the one believed to have wiped out Earth's
dinosaurs, a 5,000-strong fleet of spacecraft would need to focus a
beam
of sunlight on the surface for three or more years.

Dr Massimiliano Vasile, who led the project, said the research was not
science fiction but facing up to science fact. He said: "Asteroid
impacts
are a real threat. The Tunguska explosion in 1908 devastated an area
bigger than Greater London. With only ten spacecraft flying in
formation,
each with a 20 metre mirror, we could deflect a similar-size asteroid
into
a safe orbit in about six months.

"This technology is genuinely feasible and, unlike methods where an
explosion or impacter is used to divert the asteroid, there is no
further
risk from fragments. We have estimated, for a ten-satellite formation,
a
launch mass for each individual spacecraft of around 500kg.

"This is a smaller and lighter satellite constellation than, say, the
Galileo positioning system, so is well within our launch capabilities."

Pieces of rock and ice enter our atmosphere every day, but most are so
small that they go largely unnoticed.

Scientists have calculated that every 26-30 million years, a 10km-sized
asteroid (the size of the one believed to have wiped out the dinosaurs)
strikes the Earth.

Race against time to save the globe
ALTERNATIVE methods of saving the world from an asteroid were examined
but
rejected.

. Different types of nuclear explosion were considered but the
fragmentation of the resulting debris made this too aggressive a
method,
not to mention the dangers associated with nuclear power.

. Another option was to fix an electric propulsion system to the
asteroid,
but this would take too much time to complete before the asteroid
impacted
with the earth.

. A mass-driver system where material is excavated and catapulted away
from the asteroid, would also take too much time.

. A kinetic impactor which would knock the asteroid out of its orbit,
was
thought to require the launch of too big a space craft as was the
option
of using a large craft's own gravitational pull to drag the asteroid
away
from the earth.

The study investigated in each case the mass of spacecraft needed, the
warning time required, the orbital deflection achieved and the current
readiness of technology. Simulations were run with six different sized
asteroids.

Related topic

a.. Space science
http://news.scotsman.com/topics.cfm?tid=6
This article:http://news.scotsman.com/index.cfm?id=1590612007

Last updated: 04-Oct-07 00:44 BST

http://news.scotsman.com/index.cfm?id=1590612007

If it happens, Gary, that's pre-ordained fate & our destiny, we can't
change it !!!

They could hit Melbourne, Australia or Federal Way, Washington &
there's not a damn thing we can do about it, Gary !!!

Just enjoy each & every day as it comes -- that's Uncle Wally 's
philosophy !!!!

HOOROO

UNCLE WALLY

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