Scientists
unveil new detectors in race to save Earth from next asteroid
Science
editor Robin McKie reports from Boston as experts create warning
systems to minimise risk from impact
16
February, 2013
The
extraterrestrial double whammy that Earth only partially avoided on
Friday has triggered an immediate response from astronomers. Several
have announced plans to create state-of-the-art detection systems to
give warning of incoming asteroids and meteoroids. These include
projects backed by Nasa as well as proposals put forward by private
space contractors.
In
each case, scientists want to develop techniques that can pinpoint
relatively small but still potentially devastating meteoroids, comets
and asteroids that threaten to strike Earth. These would give notice
of impact of several days or possibly weeks and allow threatened
areas to be evacuated.
The
announcements of the various plans follow Friday's meteorite crash
that caused devastation in Chelyabinsk, Russia. On the same day, a
150ft-diameter asteroid swept to within 17,000 miles of Earth.
The
fact that the two events happened together has been dismissed as "a
cosmic coincidence" by scientists. Nevertheless, astronomers –
many gathered at the American Association for the Advancement of
Science annual meeting in Boston this weekend – have been quick to
reassure the public that they have plans to provide better warnings
of future impacts.
"The
hundreds of people injured in Russia show it is time to take action
and no longer be passive about these events," said Rick
Tumlinson, chairman of the US company Deep Space Industries. His
company is preparing to launch a series of small spacecraft later
this decade. These are aimed at surveying nearby asteroids to see if
they can be mined for metals and ores.
However
the fleet could also be used to monitor small, difficult-to-detect
objects that threaten to strike Earth. Deep Space Industries –
which is based in McLean, Virginia – proposes building 10
spacecraft at a cost of $100m (£65m) over the next four years,
though it has not indicated who will fund missions.
The
University of Hawaii has proposed a cheaper, simpler system known as
Atlas – Advanced Terrestrial-Impact Last Alert System – to be
constructed with the help of a $5m grant from Nasa. It will consist
of a series of eight telescopes, each fitted with powerful cameras,
to be built on Hawaiian islands whose clear air makes accurate
observations particularly easy.
Astronomer
Professor John Tonry, of Hawaii University, said Atlas – which is
scheduled to begin operations in 2015 – would have an extremely
high sensitivity, which he compared to the detection of a match flame
in New York when viewed from San Francisco.
He
said Atlas would give a one-week warning for a small asteroid –
which he called "a city killer" – and three weeks for a
larger "county killer". Tonry added: "That is enough
time to evacuate the area, take measures to protect buildings and
other infrastructure, and be alert to a tsunami danger generated by
ocean impacts."
Astronomers
believe they have pinpointed all large asteroids whose orbits bring
them close to Earth. To date, none has been found on a collision
course with our planet. However, small asteroids only a few dozen
metres across are very difficult to spot but massive enough to cause
local devastation.
Had
the time of entry of the Chelyabinsk meteorite into the atmosphere
varied by only a few hours, its path would have brought it down over
much larger population centres in northern England. Hence the
pressure from astronomers to develop ways to pinpoint small objects
in space.
The
announcement of these plans came as Russia revealed it was sending
more than 9,000 workers to the region around Chelyabinsk in the Ural
Mountains where Friday's meteorite crashed. President Vladimir Putin
ordered the operation after it was revealed that around 1,200 people
– including 200 children – were injured in the blast. Most are
thought to have suffered cuts and lacerations from shattered glass.
More than 50 individuals were still in hospital on Saturday.
Russian
officials have estimated that the blast – which was preceded by a
huge fireball that streaked across the morning sky on Friday –
caused damage of about 1bn roubles, roughly £20m.
Russia's
Academy of Sciences said the object that struck Chelyabinsk weighed
about 10 tonnes. It was probably part of a larger meteorite that had
entered the atmosphere at about 30km per second before breaking up.
The
energy it released was comparable with a small nuclear bomb
exploding. More than 4,000 windows were blown out by the blast,
including many at schools where pupils were in their classrooms.
Video footage has shown images of frightened, screaming children
pouring out of schools.
A
large fragment of the of the meteorite is believed to have crashed
into a frozen lake near the town of Chebarkul. However, divers who
searched the bottom of the lake reported that they could find no
trace of any lumps of meteorite. Russian authorities said the search
for the meteorite may have to wait until spring when the snow melts.
The
last time the Earth was struck by a large extraterrestrial object was
in 1908 when a huge blast – the equivalent of a medium-sized atomic
bomb – in the Tungaska in Siberia flattened more than 80 million
trees. It is thought a comet more than 100m in diameter was
responsible for the devastation.
Meteorite
'could have devastated northern UK'
Slight
difference in time at which meteorite entered atmosphere could have
resulted in widespread damage, say astronomers
16
February, 2013
The
meteorite that caused devastation in the Urals on Friday could have
struck Britain if it had entered the atmosphere at only a slightly
different time of day, astronomers revealed yesterday.
The
region around Chelyabinsk hit by the meteorite impact is 55 degrees
north, the same latitude as northern England. Had the meteorite's
timing been only few hours different, it could have caused widespread
damage in the British Isles, astronomers at the University of Hawaii
said yesterday.
If
a larger object, such as asteroid 2012 DA14 which grazed Earth later
that day, had hit the planet, it would have obliterated any city it
struck, they added.
These
events have led several teams of scientists to propose schemes aimed
at pinpointing asteroids or meteorites that could strike Earth and
devastate regions. One is to be built by Hawaii University and is
known as Atlas: Asteroid Terrestrial-Impact Last Alert System. It
will consist of a series of eight telescopes, each fitted with
powerful cameras, that would have sensitivity akin to detecting a
match flame in New York City when viewed from San Francisco.
Professor
John Tonry of Hawaii University said Atlas would give warnings of
between one to three weeks of incoming meteorites. "That is
enough time to evacuate the area of people, take measures to protect
buildings and other infrastructure, and be alert to a tsunami danger
generated by ocean impacts," he said.
News
of the plans came as Russia revealed it was sending more than 9,000
workers to the region around Chelyabinsk in the Ural mountains where
Friday's meteorite crashed. President Vladimir Putin ordered the
operation after it was revealed that around 1,200 people –
including 200 children – were injured in the blast. Most are
thought to have suffered cuts and lacerations from shattered glass.
More than 50 individuals were still in hospital on Saturday night.
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