[meteorite-list] Asteroids: Treasures of the Past and a Threat to the Future

[Ron Baalke]

http://www.esa.int/esaCP/SEMC43NFGLE_index_0.html

Asteroids: treasures of the past and a threat to the future
European Space Agency
3 April 2006

If a large asteroid such as the recently identified 2004 VD17 -- about 500 
m in diameter with a mass of nearly 1000 million tonnes -- collides with 
the Earth it could spell disaster for much of our planet. As part of ESA's 
Near-Earth Object deflecting mission Don Quijote, three teams of European 
industries are now carrying out studies on how to prevent this.

ESA has been addressing the problem of how to prevent large Near-Earth 
Objects (NEOs) from colliding with the Earth for some time. In 1996 the 
Council of Europe called for the Agency to take action as part of a 
"long-term global strategy for remedies against possible impacts". 
Recommendations from other international organisations, including the UN 
and the Organisation for Economic Cooperation and Development (OECD), soon 
followed.

In response to these and other calls, ESA commissioned a number of threat 
evaluation and mission studies through its General Studies Programme 
(GSP). In July 2004 the preliminary phase was completed when a panel of 
experts appointed by ESA recommended giving the Don Quijote 
asteroid-deflecting mission concept maximum priority for implementation.

Now it is time for industry to put forward their best design solutions for 
the mission. Following an invitation to tender and the subsequent 
evaluation process, three industrial teams have been awarded a contract to 
carry out the mission phase-A studies:

* a team with Alcatel Alenia Space as prime contractor includes 
subcontractors and consultants from across Europe and Canada; Alcatel 
Alenia Space developed the Huygens Titan probe and is currently working on 
the ExoMars mission

* a consortium led by EADS Astrium, which includes Deimos Space from Spain 
and consultants from several European countries, brings their experience 
of working on the design of many successful ESA interplanetary missions 
such as Rosetta, Mars and Venus Express

* a team led by QinetiQ (UK), which includes companies and partners in 
Sweden and Belgium, draws on their expertise in mini and micro satellites 
including ESA's SMART-1 and Proba projects 

This month the three teams began work and a critical milestone will take 
place in October when the studies will be reviewed by ESA with the support 
of an international panel of experts. The results of this phase will be 
available next year.

No reason for panic -- yet
 
The risk is still small however, and may decrease even further when new 
observations are carried out. Still, if this or any other similar-sized 
object, such as 99942 Apophis, an asteroid that will come close enough to 
the Earth in 2029 to be visible to the naked eye, collided with our planet 
the energy released could be equivalent to a significant fraction of the 
world's nuclear arsenal, resulting in devastation across national borders.

Luckily, impacts with very large asteroids are uncommon, although impacts 
with smaller asteroids are less unlikely and remote in time. In 1908 an 
asteroid that exploded over Siberia devastated an unpopulated forest area 
of more than 2000 km2; had it arrived just a few hours later, Saint 
Petersburg or London could have been hit instead.

Fossils of the Solar System
 
Asteroids are a part of our planet's history. As anyone visiting the 
Barringer Meteor Crater in Arizona, USA or aiming a small telescope at the 
Moon can tell, there is plenty of evidence that the Earth and its cosmic 
neighbourhood passed through a period of heavy asteroid bombardment. On 
the Earth alone the remains of more than 160 impacts have been identified, 
some as notorious as the Chicxulub crater located in Mexico's Yucatan 
peninsula, believed to be a trace of the asteroid that caused the 
extinction of the dinosaurs 65 million years ago.

Collisions have shaped the history of our Solar System. Because asteroids 
and comets are remnants of the turbulent period in which the planets were 
formed, they are in fact similar to 'time capsules' and carry a pristine 
record of those early days. By studying these objects it is possible to 
learn more about the evolution of our Solar System as well as 'hints' 
about the origins of life on Earth.

Comet 67P/Churyumov-Gerasimenko is one of these primitive building blocks 
and will be visited by ESA's Rosetta spacecraft in 2014, as a part of a 
very ambitious mission -- the first ever to land on a comet. Rosetta will 
also visit two main belt asteroids (Steins and Lutetia) on its way to 
comet 67P/Churyumov-Gerasimenko. The mission will help us to understand if 
life on Earth began with the help of materials such as water and organisms 
brought to our planet by 'comet seeding'.

ESA's Science programme is already looking at future challenges, and its 
Cosmic Vision 2015-2025 plan has identified an asteroid surface sample 
return as one of the key developments needed to further our understanding 
of the history and composition of our Solar System.

Work still in progress
 
Asteroids and comets are fascinating objects that can give or take life on 
a planetary scale. Experts around the world are putting all their energy 
and enthusiasm into deciphering the mysteries they carry within them.

With an early launch provisionally scheduled for 2011, Don Quijote will 
serve as a 'technological scout' not only to mitigate the chance of the 
Earth being hit by a large NEO but also for the ambitious journeys to 
explore our solar system that ESA will continue to embark upon. The 
studies now being carried out by European industry will bring the Don 
Quijote test mission one step nearer.

Note for editors
 
Don Quijote is a NEO deflection test mission based entirely on 
conventional spacecraft technologies. It would comprise two spacecraft -- 
one of them (Hidalgo) impacting an asteroid at a very high relative speed 
while a second one (Sancho) would arrive earlier at the same asteroid and 
remain in its vicinity before and after the impact to measure the 
variation on the asteroid's orbital parameters, as well as to study the 
object. Secondary mission goals have also been defined, which would 
involve the deployment of an autonomous surface package and several other 
experiments and measurements.

For more information please contact:

Andres Galvez
Advanced Concepts and Studies Office
Andres.Galvez @ esa.int