[meteorite-list] Avoiding The Fate Of The Dinosaurs - ESA Considers New NEO Missions

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 10:08:30 2004
Message-ID: <200209241721.KAA23057_at_zagami.jpl.nasa.gov>

European Space Agency
Press Release No. 60-2002
Paris, France 24 September 2002

Avoiding the fate of the dinosaurs

Tales of asteroids or comets in a collision course with the
Earth are always good to fill space in newspapers during the
quiet summer months. Is there any truth in these tales of
impending doom and if so, what is ESA doing about it?

Certainly if a large comet or asteroid were to collide with
the Earth the result could be apocalyptic. But, the
possibilities of this happening are remote. The latest
asteroid scare story to hit the press was that of 2002NT7,
believed to be about 2 km in diameter. First reports said
that 2002NT7 could collide with the Earth on 1 February
2019 at a speed of 28 km/s. The result would be widespread
devastation, if not the end of the world, predicted in some
papers.

Fortunately for those of us who will be around in 2019
the possibility of this happening is now reported to be
negligible. Although first estimates gave odds of about
1 in 100,000, now that scientists have had more time to
study this 'new' asteroid and its orbit -- only discovered
in July -- the odds have lengthened considerably.

Asteroids and comets whose orbits bring them close to the
Earth are referred to as Near Earth Objects (NEOs). Those
less than 50 m in size burn up on entry into the Earth's
atmosphere. It is estimated that around 50,000 fragments
of NEOs fall to Earth as meteorites each year, most far
too small to do any damage.

Fortunately, the larger the NEO the less likely it is to
collide with the Earth, as even a NEO 300 m in diameter
could wipe out an entire country if it hit land, and
cause even more damage if it struck an ocean, as it would
trigger the enormous waves known as tsunamis that could
devastate many coastal cities.

According to astronomers, a NEO of around 50 m in diameter
collides with the Earth every 100 to 300 years and a NEO
with a diameter of 1 km occurs every few hundred thousand
years. Very large collisions, that could threaten the
existence of all large land species, occur once every
hundred million years. To date, astronomers have
identified 600 NEOs bigger than 1 km but believe that
there are possibly half as many again still waiting to be
tracked.

But, even if the odds are on our side, the fact remains
that at some time or other the Earth will again be hit
by a large NEO, such as that thought to have wiped out
the dinosaur population 65 million years ago. So to
return to the second question, what is ESA doing about
it?

ESA and NEOs

ESA has been supporting activities to monitor and
investigate NEOs for a number of years. In ESA's view,
these are activities that surpass national boundaries
and which it considers to be a service to the
international community. ESA's space research institute
outside Rome in Italy, ESRIN, also hosts the Spaceguard
Central Node. This private non-profit scientific
organisation aims to support and coordinate NEO research
throughout the world.

Now ESA has launched a new project to seek the best ideas
from industry and academia on how to protect the Earth
from NEOs and in particular, to learn more about them.
The damage an NEO causes depends on the speed at which it
hits the Earth, its size and what it is made of. So, the
more we know about them the easier it will be to decide
which are potentially dangerous and what is the best
action to take.

In June a panel of NEO experts met to select the best six
proposals. Andrés Gálvez, one of ESA's representatives
on the panel reports, "the six winning proposals were
selected because the mission concepts would help to
answer essential questions on the NEO threat such as:
how many are there, what is their size and mass, are
they compact bodies or loose rock aggregates?

This information, as well as other data, is needed before
adequate mitigation procedures can be developed."

The winning six are:

* Don Quijote: This proposal is for a spacecraft 'named
  Hidalgo' to hit a target asteroid at high speed while
  the other, 'Sancho', observes what happens from a safe
  distance before, during and after the impact, to gather
  information on the NEO's internal structure. This will
  also test possible future mitigation techniques, such as
  whether 'Hidalgo' could be programmed to hit the asteroid
  to change its orbit so that it avoids collision with the
  Earth.

* Earthguard 1: A spacecraft using propulsion technology
  such as solar sails or electric propulsion, or 'hitching
  a ride' on a future launch, would be placed in a
  heliocentric orbit to observe NEOs from a more favourable
  viewpoint.

* ISHTAR: This would probe the interior of an NEO to study
  its structure and assess the danger with radar tomography,
  a new technology that uses ground penetrating radar to
  make images of the interior of a solid body.

* SIMONE: A fleet of low-cost small satellites would fly by
  and/or rendezvous with a number of NEOs to characterise
  the population and obtain first-hand information on the
  hazardous objects.

* EUNEOS: A space survey would be undertaken from an inner
  solar system orbit to find the most dangerous NEOs. These
  are often the most difficult to observe from ground-based
  observatories as very often these faint objects only
  appear in the daytime sky or very close to the horizon.

* Remote observation of NEOs from Space: A space-based
  observatory to carry out remote sensing and detect
  physical characteristics of NEOs, such as size,
  composition and surface properties.

Andrea Carusi, President of the Spaceguard Foundation,
believes "it is very important that ESA, one of the largest
space agencies, and one that is already deeply involved in
support of NEO studies, has decided to take a further step
in this direction".

Preliminary studies, funded by the Agency's General Studies
Programme, are now under way for the six proposals. Once
these are submitted in 2003, ESA will judge whether one or
more of the proposed missions is feasible and merits further
development.

For further information, please contact:

ESA Media Relations Service
Tel: +33(0)1.53.69.7155
Fax: +33(0)1.53.69.7690
Received on Tue 24 Sep 2002 01:21:09 PM PDT