[meteorite-list] Near Earth Objects - What Lies Ahead?

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Mon Nov 28 15:18:54 2005
Message-ID: <200511282017.jASKHNc13853_at_zagami.jpl.nasa.gov>

ottp://www.pparc.ac.uk/Nw/NEO_conf.asp
 
Near Earth Objects - what lies ahead?
Particle Physics and Astronomy Research Council
November 28, 2005

Telescope facilities across the world are watching the skies for rocky
remnants from outer space on a collision course with planet Earth.
Currently one or two of these so called 'Near Earth Objects' [NEOs] are
being recorded each day but fortunately for humankind the vast majority
are the size of a human fist and pose no threat. Nevertheless, the
presence of large impact craters on Earth provides dramatic evidence of
past collisions, some of which have been catastrophic for the planet's
species, as was the case with the dinosaurs. This week, experts from
across Europe and the US met in London to consider current and future
efforts to monitor NEOs in order to better predict those with Earth
impacting trajectories, since it is inevitable that a catastrophic
collision will happen again in the future.

Professor Monica Grady, a leading expert on meteorites from the Open
University explains, "It's simply a question of when, not if, a NEO
collides with the Earth. Many of the smaller objects break up when they
reach Earth's atmosphere and have no impact. However, a NEO larger than
1 km will collide with Earth every few hundred thousand years and an NEO
larger than 6 km, which could cause a mass extinction, will collide with
Earth every hundred million years. And we are overdue for a big one!"

NEO's, remnants from the formation of the inner planets, range in size
from 10 metre objects to those in excess of 1 km. It is estimated that
100 fist sized meteorites, fragments of NEO's, fall to Earth on a daily
basis but larger objects impact with Earth on a much less regular basis.

Professor Alan Fitzsimmons from Queens University Belfast is a UK
astronomer (supported by the Particle Physics and Astronomy Research
Council) involved in the study of NEO's, using telescope facilities such
as the European Southern Observatory's Very Large telescope in Chile,
the Isaac Newton Telescope in La Palma and the Faulkes Telescope in
Hawaii. He said, "By the end of the decade as new dedicated facilities,
such as the Pan-STARR project in Hawaii, come on line there will be a
quantum leap in the discovery of NEO's - with rates anticipated to
increase to hundreds per day. This will provide us with a greater
ability to determine which ones are on a potential Earth colliding
trajectory."

Studies of one such asteroid (Apophis), which was discovered in
June2004, have shown that there is a low probability that this object
will impact the Earth in 2036. This has raised a whole series of issues
about the prospect of deflecting the asteroid before a very close
approach in 2029. Government's across the world are looking at the issue
and in particular at the technologies and methods required to carry out
an asteroid deflection manoeuvre in space.

The European Space Agency's NEO Mission Advisory Panel (NEOMAP), of
which Professor Fitzsimmons is a member, has selected "Don Quixote" as
their preferred option for an asteroid deflecting test mission. Don
Quixote would comprise two spacecraft - one of them (Hildalgo) would
impact the asteroid at a very high relative speed while the second
spacecraft (Sancho) would arrive earlier to monitor the effect of the
impact to measure the variation of the asteroid's orbital parameters.
This attempt to deflect an incoming NEO would act as a precursor mission
with the primary objective of modifying the trajectory of a
"non-threatening" asteroid.

Richard Tremayne-Smith, from the British National Space Centre, heads up
the coordination of UK NEO activity and helps provide an international
lead on NEO efforts on the issue. He said, "NEO collisions are the only
known natural disaster that can be avoided by applying appropriate
technology - and so it is the interest of Governments across the World
to take interest in this global issue. Here in the UK we take the matter
very seriously and progress is being made in taking forward the
recommendations of the UK NEO Task Force Report in an international arena."

The current method of studying NEOs is achieved through a combination of
3 different methods:- the study of meteorites to understand their
structure and composition; earth based astronomical observations of
asteroids; and space based observations and encounters with asteroids.

Much can be understood about the nature of asteroids from the study of
meteorites which are fragments of asteroids that have broken up and
fallen to Earth. Professor Grady explains how the ground based study of
meteorites is crucial to future plans for dealing with asteroids.

"In order to define successful strategies for deflecting asteroids that
might collide with Earth, it is essential to understand the material
properties such as the composition, strength and porosity of asteroids.
By putting together such information with data from both ground based
and space based studies we can begin to build an accurate picture of
these diverse phenomena."

UK scientists are involved in a number of other missions which will also
be investigating the properties of asteroids and comets. This includes
NASA's Stardust mission which collected samples from Comet Wild 2 in
January 2004. These samples are set to return to Earth in January 2006
and scientists from the Open University will be involved in their
analysis. The European Space Agency's Rosetta mission which is currently
on route to Comet Churyumov-Gerasimenko will pass by two asteroids,
Steins and Lutetia, before reaching its target in 2014, gathering data
about their properties as it flies past.

Contacts

Gill Ormrod (gill.ormrod_at_pparc.ac.uk) - PPARC Press Office
Tel: 01793 442012. Mobile: 0781 8013509

Fiona Hatton (fiona.hatton_at_bnsc.gsi.gov.uk) - British National
Space Centre
Tel: 020 7215 0806

Professor Monica Grady (mailto:m.m.grady_at_open.ac.uk0)
Tel: 01908 659251. Mobile: 07921911208

Professor Alan Fitzsimmons (mailto:A.Fitzsimmons_at_qub.ac.uk)
Tel: +44 (0) 2890-973124. Mobile: 07834 318834

Kevin Yates (mailto:kevinyates_at_nearearthobjects.org.uk) - Near Earth
Object Information Centre
Tel: 0116 258 2130. Mobile: 07740 896141
Received on Mon 28 Nov 2005 03:17:23 PM PST