[meteorite-list] Deflecting Asteroids Could Lead To More Versttile Spaceprobes

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Tue Sep 27 17:55:39 2005
Message-ID: <200509272127.j8RLRYA07987_at_zagami.jpl.nasa.gov>

http://www.eurekalert.org/pub_releases/2005-09/eaps-dac092705.php

Public release date: 27-Sep-2005
Contact: Natasha Richardson
natasha.richardson_at_epsrc.ac.uk
44-1-793-444-404
Engineering and Physical Sciences Research Council <http://www.epsrc.ac.uk>
  
Deflecting asteroids could lead to more versatile spaceprobes

EPSRC Press Release

The UK's first engineering feasibility study into missions for
deflecting asteroids has begun.

The Engineering and Physical Sciences Research Council (EPSRC) is
funding a new three-year study into interception and deflection
strategies for asteroids found to be on a collision course with Earth.
Although there have been similar studies in the past, Dr Gianmarco
Radice, department of Aerospace Engineering, University of Glasgow, and
Professor Colin McInnes, department of Mechanical Engineering,
University of Strathclyde, are approaching the subject in a new way.

"We will be looking at this as engineers. So we want to investigate the
practicality of different deflection strategies," says McInnes. In other
words, it is no use having a brilliant deflection scheme if no one can
build it with current technology.

Although Hollywood blockbusters have popularised the idea of using
nuclear weapons to blow up asteroids, the study will investigate more
realistic alternatives such as space mirrors. These would be angled to
focus sunlight onto the incoming object. The intense heat would boil
away a section of the asteroid, creating a natural rocket that pushes
the asteroid in the opposite direction. The study will also look into
high-speed collisions to literally knock an asteroid out of the way
using no explosives, just a 'battering ram' spacecraft.

Asteroids have widely differing compositions, ranging from pure rock or
even metal to ice and snow. Knowing what an asteroid is made from, and
therefore its likely strength, is the crucial first step in determining
the best way to divert it without shattering it. "One of the main
objectives of this study is to try to associate a particular deflection
strategy with a particular type of asteroid that has to be deviated,"
says Radice.

The internal arrangement of Near Earth Objects (NEOs) can critically
affect the deviation strategy. Some asteroids, known as rubble piles,
are not solid slabs of rock but loose assemblages. Slamming an object
into a rubble pile would not be very effective in altering its course,
because the rubble would absorb the energy of impact rather like a
crumple zone on a car absorbs a crash. Instead, scenarios which melt
part of the surface, such as space mirrors, producing jets of gas that
gradually ease the object into a new orbit, are favoured.

Yet this is about more than just diverting asteroids, no matter how
critical that need may one day become. The biggest part of the study
concerns how to intercept such targets. In conventional space
exploration, everything is precisely worked out beforehand and targets
are chosen that have well-known orbits. That's how NASA recently
bulls-eyed comet Tempel 1 with its Deep Impact mission.

However, a dangerous object is likely to be newly discovered and that
means its orbit will be poorly known. "We'd probably have to launch a
deflection mission without a clear idea of where we're aiming," says
McInnes. So, the study will seek to find the best strategies for
launching space missions into approximate intercept orbits that can be
adjusted later.

To do this, it will investigate the additional fuel that such a
spacecraft would require. Because fuel is heavy, spacecraft are
traditionally designed to carry little extra. That will have to change
with this new approach to space exploration.

Such seat-of-the-pants flying could result in more versatile spacecraft
across the board. These would be better able to respond to a variety of
unexpected situations. As well as fuel considerations, the team will
investigate 'general purpose' orbits and flexible navigation strategies
that keep a spacecraft's options open for longer, before committing it
to a final destination.

###

Notes for Editors:

There are no asteroids or comets currently known to be on a collision
course with Earth.

Astronomers call any asteroids or comets that pass close to our planet,
Near Earth Objects (NEOs). Typically, NEOs are mountain-sized objects.

Shattering an NEO is not a valid deflection strategy because breaking
one object into hundreds or even thousands of pieces does not markedly
alter its trajectory through space. Instead of having a cannon-ball
heading for Earth, shattering it simply turns it into buckshot.

For more information contact:

Dr Gianmarco Radice, Tel: 0141 330 4068, E-mail: gradice_at_aero.gla.ac.uk

Professor Colin McInnes, Tel: 0141 548 2049, Email:
colin.mcinnes_at_strath.ac.uk
Strathclyde press office, Tel: 0141 548 4123

An image (Asteroid.jpg) is available from the EPSRC Press Office,
contact Lisa Green, Tel: 01793 442806, E-mail: lisa.green_at_epsrc.ac.uk

Suggested caption information for 'Asteroid.jpg':

On 4 July 2005, NASA collided a projectile with comet Tempel 1 for
scientific reasons. One day in the future, scientists anticipate having
to do this on a much bigger scale in order to actually shove a celestial
body off its collision course with Earth. Image courtesy:
NASA/JPL-Caltech/UMD.
 
Received on Tue 27 Sep 2005 05:27:33 PM PDT