[meteorite-list] ESA Studies Missions to Safeguard the Earth

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 10:23:51 2004
Message-ID: <200303262026.MAA11965_at_zagami.jpl.nasa.gov>

European Space Agency
Paris, 26 March 2003
Press Release
N° 19-2003


ESA Studies Missions to Safeguard the Earth

Early on the morning of 30 June 1908, the vast forest of western Siberia
was illuminated by a strange apparition: an alien object streaking across
the cloudless sky. White hot from its headlong plunge into the Earth’s
atmosphere, the intruder exploded about 8 km above the ground, flattening
trees over an area of 2000 square kilometres.

Despite the huge detonation, equivalent to a 10 megaton nuclear warhead
(about 500 times the energy of the Hiroshima atomic bomb), there were few
if any casualties in the sparsely populated taiga. If the Tunguska object
– probably an asteroid about twice the size of a tennis court – had
exploded over London or Paris, the list of casualties would have run into
millions.

Fortunately, cataclysmic events caused by incoming near-earth objects
(NEOs) are few and far between. Current estimates suggest that a 50 metre
Tunguska-like object is likely to collide with the Earth once every
100-300 years. A 1 km object, which typically arrives every few hundred
thousand years, could wipe out an entire country. An impact in the ocean
would be no better, generating enormous waves (known as tsunamis) that
would devastate coastal areas thousands of kilometres away.

An increasing awareness of the potentially disastrous consequences of such
impacts has driven recent efforts to detect and categorise the larger
Earth-threatening objects. However, much more needs to be done if the
millions of Tunguska-like objects are to be found and catalogued. Only
then can advance warning of pending impacts be provided and measures be
taken to reduce the threat.

Despite the introduction of increasingly sophisticated search programmes
in various parts of the world, the search for objects heading our way
needs to expand into space. Only space-based observatories can provide
the all-sky coverage required and detect Earth-crossing objects that would
normally be hidden in the glare of the Sun.

In July 2002 the general studies programme of the European Space Agency
(ESA) provided funding for preliminary studies on six space missions that
could make significant contributions to our knowledge of NEOs.

“The six proposals were selected because the mission concepts would help
to answer essential questions on the NEO threat, such as how many there
are, their size and mass, and whether they are compact bodies or loose
rock aggregates,” said Andrés Gálvez, head of the Advanced Concepts Team
at ESA’s European Space Research Technology Centre (ESTEC) in the
Netherlands.

“This information, as well as other data, is needed before appropriate
mitigation procedures can be developed,” he said.

“There are two broad categories. The observatory missions are able to
detect and track many more NEOs than can be seen from the ground. This
enables astronomers to calculate their orbits and predict whether they
will offer a threat to the Earth far into the future."

“The flyby/rendezvous missions are designed to look at a small number of
NEOs in great detail, sending back information on their size, composition,
density, internal structure and so on. This is important because we need
to know as much as possible about how they will behave if we try to divert
them from a collision course with Earth.”

The six missions under study were:

· Don Quijote: This proposal involves the launch of two spacecraft to
test technologies required to deflect an asteroid heading towards Earth.
The ‘Hidalgo’ spacecraft will be targeted to impact a 500-metre-diameter
asteroid at a relative speed of 10 km/s. Its companion, known as ‘Sancho’
will deliver a number of sensors to the surface of the asteroid and
observe from a safe distance what happens during and after the high speed
collision. This will provide valuable information on the NEO’s internal
structure.

· Earthguard 1: A proposal to mount a “hitchhiker” telescope on a
spacecraft en route to the inner Solar System, e.g. ESA’s BepiColombo
Mercury orbiter. The telescope would detect Earth-crossing asteroids
larger than about 100 metres, which are very difficult or impossible to
detect with ground-based telescopes.

· EUNEOS: A medium-sized telescope mounted on a dedicated spacecraft
platform that would search for the most dangerous NEOs from inside the
orbit of Venus. Its main goal is to detect 80% of the potentially
hazardous objects down to a few hundreds of metres in size. It is
estimated that this could be attained in 5 years. By systematic
re-detection of the objects, their orbits would then be determined with
high accuracy.

· ISHTAR: In addition to measuring the mass, density and surface
properties of an NEO, this spacecraft would probe the interior of an NEO
in order to study its structure and internal strength. This would be done
using radar tomography, a new technology that uses ground-penetrating
radar to make images of the interior of a solid body.

· SIMONE: A fleet of five low-cost microsatellites that would each fly by
and/or rendezvous with a different type of NEO. Each spacecraft would
carry a suite of scientific instruments that would provide valuable
insights into the nature of large asteroids (400 – 1 000 metres in
diameter) with different physical and compositional properties. Low-thrust
ion propulsion would be used to rendezvous with each target.

· 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.

“We now have a number of excellent proposals that are both feasible and
affordable,” said Franco Ongaro, head of ESA’s Advanced Concepts & Studies
Office.

“These phase A studies by industry and academia, which were completed in
January 2003, provide a valuable framework for developing future missions.
They will now be discussed within the Agency and with ESA’s international
partners in order to determine how best to proceed.”

LINKS:
ESA NEO studies: http://www.esa.int/gsp/completed/neo/index.htm
ESA Advanced Concepts Team: http://www.esa.int/gsp/ACT/index.htm


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 Wed 26 Mar 2003 03:26:28 PM PST