debbiejo
To see this story with its related links on the Guardian Unlimited site, go to http://www.guardian.co.uk
It's called Apophis. It's 390m wide. And it could hit Earth in 31 years time
Scientists call for plans to change asteroid's path Developing technology could
take decades
Alok Jha
Wednesday December 07 2005
The Guardian
In Egyptian myth, Apophis was the ancient spirit of evil and destruction, a
demon that was determined to plunge the world into eternal darkness.
A fitting name, astronomers reasoned, for a menace now hurtling towards Earth
from outerspace. Scientists are monitoring the progress of a 390-metre wide
asteroid discovered last year that is potentially on a collision course with
the planet, and are imploring governments to decide on a strategy for dealing
with it.
Nasa has estimated that an impact from Apophis, which has an outside chance of
hitting the Earth in 2036, would release more than 100,000 times the energy
released in the nuclear blast over Hiroshima. Thousands of square kilometres
would be directly affected by the blast but the whole of the Earth would see
the effects of the dust released into the atmosphere.
And, scientists insist, there is actually very little time left to decide. At a
recent meeting of experts in near-Earth objects (NEOs) in London, scientists
said it could take decades to design, test and build the required technology to
deflect the asteroid. Monica Grady, an expert in meteorites at the Open
University, said: "It's a question of when, not if, a near Earth object
collides with Earth. Many of the smaller objects break up when they reach the
Earth's atmosphere and have no impact. However, a NEO larger than 1km
will collide with Earth every few hundred thousand years and a NEO larger than
6km, which could cause mass extinction, will collide with Earth every hundred
million years. We are overdue for a big one."
Apophis had been intermittently tracked since its discovery in June last year
but, in December, it started causing serious concern. Projecting the orbit of
the asteroid into the future, astronomers had calculated that the odds of it
hitting the Earth in 2029 were alarming. As more observations came in, the odds
got higher.
Having more than 20 years warning of potential impact might seem plenty of
time. But, at last week's meeting, Andrea Carusi, president of the Spaceguard
Foundation, said that the time for governments to make decisions on what to do
was now, to give scientists time to prepare mitigation missions. At the peak of
concern, Apophis asteroid was placed at four out of 10 on the Torino scale - a
measure of the threat posed by an NEO where 10 is a certain collision which
could cause a global catastrophe. This was the highest of any asteroid in
recorded history and it had a 1 in 37 chance of hitting the Earth. The threat
of a collision in 2029 was eventually ruled out at the end of last year.
Alan Fitzsimmons, an astronomer from Queen's University Belfast, said: "When it
does pass close to us on April 13 2029, the Earth will deflect it and change
its orbit. There's a small possibility that if it passes through a particular
point in space, the so-called keyhole, ... the Earth's gravity will change
things so that when it comes back around again in 2036, it will collide with
us." The chance of Apophis passing through the keyhole, a 600-metre patch of
space, is 1 in 5,500 based on current information.
There are no shortage of ideas on how to deflect asteroids. The Advanced
Concepts Team at the European Space Agency have led the effort in designing a
range of satellites and rockets to nudge asteroids on a collision course for
Earth into a different orbit.
No technology has been left unconsidered, even potentially dangerous ideas such
as nuclear powered spacecraft. "The advantage of nuclear propulsion is a lot of
power," said Prof Fitzsimmons. "The negative thing is that ... we haven't done
it yet. Whereas with solar electric propulsion, there are several spacecraft
now that do use this technology so we're fairly confident it would work."
The favoured method is also potentially the easiest - throwing a spacecraft at
an asteroid to change its direction. Esa plans to test this idea with its Don
Quixote mission, where two satellites will be sent to an asteroid. One of them,
Hidalgo, will collide with the asteroid at high speed while the other, Sancho,
will measure the change in the object's orbit. Decisions on the actual design
of these probes will be made in the coming months, with launch expected some
time in the next decade. One idea that seems to have no support from
astronomers is the use of explosives.
Prof Fitzsimmons. "If you explode too close to impact, perhaps you'll get hit
by several fragments rather than one, so you spread out the area of damage."
In September, scientists at Strathclyde and Glasgow universities began computer
simulations to work out the feasibility of changing the directions of asteroids
on a collision course for Earth. In spring next year, there will be another
opportunity for radar observations of Apophis that will help astronomers work
out possible future orbits of the asteroid more accurately.
If, at that stage, they cannot rule out an impact with Earth in 2036, the next
chance to make better observations will not be until 2013. Nasa has argued that
a final decision on what to do about Apophis will have to be made at that
stage.
"It may be a decision in 2013 whether or not to go ahead with a full-blown
mitigation mission, but we need to start planning it before 2013," said Prof
Fitzsimmons. In 2029, astronomers will know for sure if Apophis will pose a
threat in 2036. If the worst-case scenarios turn out to be true and the Earth
is not prepared, it will be too late. "If we wait until 2029, it would seem
unlikely that you'd be able to do anything about 2036," said Mr Yates.
....OH NO!!!....We're gonna die!!
It's called Apophis. It's 390m wide. And it could hit Earth in 31 years time
Scientists call for plans to change asteroid's path Developing technology could
take decades
Alok Jha
Wednesday December 07 2005
The Guardian
In Egyptian myth, Apophis was the ancient spirit of evil and destruction, a
demon that was determined to plunge the world into eternal darkness.
A fitting name, astronomers reasoned, for a menace now hurtling towards Earth
from outerspace. Scientists are monitoring the progress of a 390-metre wide
asteroid discovered last year that is potentially on a collision course with
the planet, and are imploring governments to decide on a strategy for dealing
with it.
Nasa has estimated that an impact from Apophis, which has an outside chance of
hitting the Earth in 2036, would release more than 100,000 times the energy
released in the nuclear blast over Hiroshima. Thousands of square kilometres
would be directly affected by the blast but the whole of the Earth would see
the effects of the dust released into the atmosphere.
And, scientists insist, there is actually very little time left to decide. At a
recent meeting of experts in near-Earth objects (NEOs) in London, scientists
said it could take decades to design, test and build the required technology to
deflect the asteroid. Monica Grady, an expert in meteorites at the Open
University, said: "It's a question of when, not if, a near Earth object
collides with Earth. Many of the smaller objects break up when they reach the
Earth's atmosphere and have no impact. However, a NEO larger than 1km
will collide with Earth every few hundred thousand years and a NEO larger than
6km, which could cause mass extinction, will collide with Earth every hundred
million years. We are overdue for a big one."
Apophis had been intermittently tracked since its discovery in June last year
but, in December, it started causing serious concern. Projecting the orbit of
the asteroid into the future, astronomers had calculated that the odds of it
hitting the Earth in 2029 were alarming. As more observations came in, the odds
got higher.
Having more than 20 years warning of potential impact might seem plenty of
time. But, at last week's meeting, Andrea Carusi, president of the Spaceguard
Foundation, said that the time for governments to make decisions on what to do
was now, to give scientists time to prepare mitigation missions. At the peak of
concern, Apophis asteroid was placed at four out of 10 on the Torino scale - a
measure of the threat posed by an NEO where 10 is a certain collision which
could cause a global catastrophe. This was the highest of any asteroid in
recorded history and it had a 1 in 37 chance of hitting the Earth. The threat
of a collision in 2029 was eventually ruled out at the end of last year.
Alan Fitzsimmons, an astronomer from Queen's University Belfast, said: "When it
does pass close to us on April 13 2029, the Earth will deflect it and change
its orbit. There's a small possibility that if it passes through a particular
point in space, the so-called keyhole, ... the Earth's gravity will change
things so that when it comes back around again in 2036, it will collide with
us." The chance of Apophis passing through the keyhole, a 600-metre patch of
space, is 1 in 5,500 based on current information.
There are no shortage of ideas on how to deflect asteroids. The Advanced
Concepts Team at the European Space Agency have led the effort in designing a
range of satellites and rockets to nudge asteroids on a collision course for
Earth into a different orbit.
No technology has been left unconsidered, even potentially dangerous ideas such
as nuclear powered spacecraft. "The advantage of nuclear propulsion is a lot of
power," said Prof Fitzsimmons. "The negative thing is that ... we haven't done
it yet. Whereas with solar electric propulsion, there are several spacecraft
now that do use this technology so we're fairly confident it would work."
The favoured method is also potentially the easiest - throwing a spacecraft at
an asteroid to change its direction. Esa plans to test this idea with its Don
Quixote mission, where two satellites will be sent to an asteroid. One of them,
Hidalgo, will collide with the asteroid at high speed while the other, Sancho,
will measure the change in the object's orbit. Decisions on the actual design
of these probes will be made in the coming months, with launch expected some
time in the next decade. One idea that seems to have no support from
astronomers is the use of explosives.
Prof Fitzsimmons. "If you explode too close to impact, perhaps you'll get hit
by several fragments rather than one, so you spread out the area of damage."
In September, scientists at Strathclyde and Glasgow universities began computer
simulations to work out the feasibility of changing the directions of asteroids
on a collision course for Earth. In spring next year, there will be another
opportunity for radar observations of Apophis that will help astronomers work
out possible future orbits of the asteroid more accurately.
If, at that stage, they cannot rule out an impact with Earth in 2036, the next
chance to make better observations will not be until 2013. Nasa has argued that
a final decision on what to do about Apophis will have to be made at that
stage.
"It may be a decision in 2013 whether or not to go ahead with a full-blown
mitigation mission, but we need to start planning it before 2013," said Prof
Fitzsimmons. In 2029, astronomers will know for sure if Apophis will pose a
threat in 2036. If the worst-case scenarios turn out to be true and the Earth
is not prepared, it will be too late. "If we wait until 2029, it would seem
unlikely that you'd be able to do anything about 2036," said Mr Yates.
....OH NO!!!....We're gonna die!!
