Comet dust brought back to Earth: paving the way for Rosetta(Forwarded)

ESA News
http://www.esa.int

12 January 2006

Comet dust brought back to Earth: paving the way for Rosetta

Scientists around the world eagerly await the arrival of sample particles
from Comet Wild 2, which are being brought back to Earth by the US
Stardust spacecraft on 15 January this year.

The NASA Stardust mission was launched over seven years ago and has
travelled several thousand millions of kilometres in deep space, chasing
Comet Wild 2.

In January 2004, the spacecraft encountered the comet to collect samples
of particles ejected from its nucleus.

This was achieved with a sample canister containing cells filled with
'Aerogel', an extremely lightweight, porous material based on silicon
technology, ideal for slowing down the fast-moving dust particles and
collecting them. These particles are moving at 'hypervelocities', i.e.
speeds of up to seven kilometres per second.

During the encounter with Wild 2, the canister was exposed to the cometary
particles and then retracted inside the spacecraft and stored in its
Sample Return Capsule. The spacecraft then began its two-year journey back
to Earth to return carrying its precious cargo. Also a sample of
interstellar dust was collected during the journey.

When we want to understand the origin and evolution of the Solar System,
comets are among the most informative of its inhabitants. They formed four
and a half thousand million years ago and have remained almost unchanged
since then.

Studying them can provide important clues about the origin of the material
out of which the Solar System formed, and could even help in understanding
the origins of life on Earth.

"Missions like Stardust provide not only valuable data by the first-ever
study in terrestrial laboratories of particles ejected from a known comet
and collected in the very close vicinity to it," said Gerhard Schwehm,
ESA's Rosetta Project Scientist.

"Results from such missions, which include ESA's Giotto spacecraft to
Comet Halley in 1986, are also very important for the preparation and
fine-tuning of the scientific investigations on future cometary missions,
such as the European comet-chaser Rosetta."

Launched in 2004, Rosetta is now travelling on a long route around the Sun
to rendezvous with Comet Churyumov-Gerasimenko in 2014 and deliver a
lander onto its surface.

With Stardust, scientists will have access to information about particles
collected from the 'coma', the halo of dust and gas surrounding the comet
tail.

"These tiny particles, mostly micrometres in size, will be cut into even
finer pieces and will be analysed with the very best instruments and at
the highest level of detail for Earth-based labs," continued Schwehm.

"With Rosetta, we will study the comet in situ in all its aspects -- the
tail, the coma and even the surface, the comet 'mantle'. Instead of
bringing the comet material to our laboratories, Rosetta will take the
'laboratory' to the comet.

"In particular, our sophisticated suite of instruments will allow us not
only to fully characterise the comet's particle content -- chemical
composition and other physical properties -- but also the volatile
content. This means we don't potentially lose any of these properties
during a transport back to Earth," he adds.

"However, thanks to Stardust, the analysis of coma particles on Earth will
provide the whole scientific community with an unprecedented close-up
view. For instance, the analysis of the 'isotopic ratio' of the elements
in the dust grains (finding the percentage and the nature of 'decayed'
atoms in the dust) gives important information about where and how this
material was formed," concluded Schwehm.

Notes to editors:

Stardust is a mission in NASA's Discovery Programme of lower cost, highly
focused Solar System investigations. It is a collaborative mission between
NASA, universities and industry partners.

Among its three dedicated science packages, the mission hosts a fully
European experiment -- the Comet and Interstellar Dust Analyser (CIDA),
built by the Max Planck Institut für Extraterrestrische Physik, Germany.

The purpose of the instrument, derived from the design of an instrument
flown on ESA's Giotto mission and the Russian Vega spacecraft to Comet
Halley, is to intercept cometary dust for a real-time preliminary analysis
of its chemical composition.

Another European contribution is provided by the Planetary and Space
Science Research Institute of the Open University, UK. This includes the
design and provision of sensors for the Dust Flux Monitoring instrument,
dust coma modelling, development of sample extraction and characterisation
techniques in Aerogel. This group also builds strongly on their experience
gained in their involvement on the Giotto mission.

Rosetta's main objective is to rendezvous with Comet
67P/Churyumov-Gerasimenko. It will study the nucleus of the comet and its
environment in great detail for a period of nearly two years, and land a
probe on its surface. ESA's Rosetta will be the first mission ever to
orbit and land on a comet.

For further information please contact:

Gerhard Schwehm, ESA Rosetta Project Scientist
E-mail: gerhard.schwehm @ esa.int

Michel van Baal, ESA/ESTEC Communications Office
Tel: (office hours) +31 71 565 3006
Tel: (weekend) +31 651 181 553
E-mail: michel.van.baal @ esa.int

More about...

* ESA's comet chaser: Rosetta
http://www.esa.int/SPECIALS/Rosetta/index.html
* Rosetta factsheet
http://www.esa.int/esaSC/SEMJUZS1VED_index_0.html

Related articles

* Evidence for more dust than ice in comets
http://www.esa.int/esaCP/SEMUSK5Y3EE_index_0.html
* Life of a comet
http://www.esa.int/SPECIALS/Rosetta/SEM3NV0PGQD_0.html
* Tempel 1: Biography of a comet
http://www.esa.int/SPECIALS/Rosetta/SEMIUG0DU8E_0.html
* Rosetta monitors Deep Impact
http://www.esa.int/esaCP/SEMCOZ1DU8E_index_0.html
* XMM-Newton to observe Deep Impact
http://www.esa.int/esaCP/SEMSZC2DU8E_index_0.html
* Hubble sees outburst from Deep Impact comet
http://www.esa.int/esaCP/SEMSBN5DIAE_index_0.html
* ESA observes Deep Impact from Earth
http://www.esa.int/SPECIALS/Rosetta/SEMNRO5DIAE_0.html
* Dust and gas from Comet 9P/Tempel 1 seen by ESA OGS
http://www.esa.int/esaCP/SEMQR06DIAE_index_0.html
* Tempel 1 is weak X-ray source, XMM-Newton confirms
http://www.esa.int/esaCP/SEMXA46DIAE_index_0.html

Related links

* NASA Stardust
http://www.nasa.gov/mission_pages/st...ain/index.html

IMAGE CAPTIONS:

[Image 1:
http://www.esa.int/esaCP/SEM7G5MZCIE_index_1.html]
This image of Comet Wild 2 was one of 72 taken with the navigation camera
on NASA's Stardust spacecraft during its encounter with the comet between
31 December 2003 and 2 January 2004. The Wild 2 nucleus measures five
kilometres wide.

Credits: NASA

[Image 2:
http://www.esa.int/esaCP/SEM7G5MZCIE...html#subhead1]
Artist's impression of NASA's Stardust spacecraft

Credits: NASA

[Image 3:
http://www.esa.int/esaCP/SEM7G5MZCIE...html#subhead2]
Rosetta's 11-year expedition began in February 2004, with an Ariane-5
launch from Kourou in French Guiana. Rosetta will be the first spacecraft
to orbit and land on a comet¹s nucleus.

Credits: ESA/AOES Medialab