[meteorite-list] Two Asteroid Flybys for Rosetta

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 10:32:48 2004
Message-ID: <200403111630.IAA21272_at_zagami.jpl.nasa.gov>


Two asteroid fly-bys for Rosetta
European Space Agency
11 March 2004

ESA PR 15-2004.

Today the Rosetta Science Working Team has made the final selection of
the asteroids that Rosetta will observe at close quarters during its
journey to Comet 67P/Churyumov-Gerasimenko. Steins and Lutetia lie
in the asteroid belt between the orbits of Mars and Jupiter.
Rosetta's scientific goals always included the possibility of studying
one or more asteroids from close range. However, only after Rosetta's launch
and its insertion into interplanetary orbit could the ESA mission managers
assess how much fuel was actually available for fly-bys. Information from the
European Space Operations Centre (ESOC) in Germany enabled Rosetta's
Science Working Team to select a pair of asteroids of high scientific interest,
well within the fuel budget.

The selection of these two excellent targets was made possible by the high
accuracy with which the Ariane 5 delivered the spacecraft into its orbit.
This of course leaves sufficient fuel for the core part of the mission,
orbiting Comet 67P/Churyumov-Gerasimenko for 17 months when Rosetta reaches
its target in 2014.

Asteroids are primitive building blocks of the Solar System, left over from
the time of its formation about 4600 million years ago. Only a few asteroids
have so far been observed from nearby. They are very different in shape and
size, ranging from a few kilometres to over 100 kilometres across, and in
their composition.

The targets selected for Rosetta, Steins and Lutetia, have rather different
properties. Steins is relatively small, with a diameter of a few kilometres,
and will be visited by Rosetta on 5 September 2008 at a distance of just
over 1700 kilometres. This encounter will take place at a relatively low
speed of about 9 kilometres per second during Rosetta's first excursion
into the asteroid belt.

Lutetia is a much bigger object, about 100 kilometres in diameter. Rosetta
will pass within about 3000 kilometres on 10 July 2010 at a speed of 15
kilometres per second. This will be during Rosetta's second passage
through the asteroid belt.

Rosetta will obtain spectacular images as it flies by these primordial rocks.
Its onboard instruments will provide information on the mass and density of
the asteroids, thus telling us more about their composition, and will also
measure their subsurface temperature and look for gas and dust around them.

Rosetta began its journey just over a week ago, on 2 March, and is well on
its way. Commissioning of its instruments has already started and is
proceeding according to plan.

"Comets and asteroids are the building blocks of our Earth and the other
planets in the Solar System. Rosetta will conduct the most thorough analysis
so far of three of these objects," said Prof. David Southwood, Director of
ESA's Science Programme. "Rosetta will face lots of challenges during its
12-year journey, but the scientific insights that we will gain into the
origin of the Solar System and, possibly, of life are more than rewarding."

For further information, please contact:

ESA Media Relations Division
Tel: +33(0)
Fax: +33(0)
Received on Thu 11 Mar 2004 11:30:25 AM PST

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