[meteorite-list] Lutetia Asteroid in Rosetta's Spotlight

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Fri, 26 Jan 2007 12:12:44 -0800 (PST)
Message-ID: <200701262012.MAA29697_at_zagami.jpl.nasa.gov>

http://www.esa.int/esaSC/SEMNRESMTWE_index_0.html

Lutetia asteroid in Rosetta's spotlight
European Space Agency
26 January 2007

Earlier this month ESA's Rosetta had a first look at asteroid
21-Lutetia, one of the targets of its long mission. The onboard camera
OSIRIS imaged the asteroid passing through its field of view during the
spacecraft's gradual approach to Mars. The planet will be reached on 25
February 2007 for the mission's next gravity assist.
 
During its long trek to final destination (comet 67P
Churyumov-Gerasimenko), Rosetta is planned to study two asteroids -
2867-Steins and 21-Lutetia, both lying in the asteroid belt between the
orbits of Mars and Jupiter. Asteroids, as well as comets, carry
important information about the origin of the Solar System - a better
understanding of which is one of the primary goals of Rosetta.

The two asteroids will be visited at close range in September 2008 and
July 2010, respectively, but the Rosetta scientists have already taken
the opportunity to collect preliminary data about them. This opportunity
will help scientists to better prepare for the broader observation
campaigns of the two asteroids to come at later stage.

Steins was imaged by Rosetta on March 11, while Lutetia was first imaged
by Rosetta during a 36-hour observation campaign on 2 and 3 January
2007, when the spacecraft was flying at about 245 million kilometres
from the asteroid. OSIRIS, the Optical, Spectroscopic, and Infrared
Remote Imaging System mounted onboard the Rosetta orbiter, was switched
on for this remote sensing observation.

Lutetia can be seen as the near-stationary spot visible at the centre of
the animated sequence presented in this article. The scattered light
spots seen in the movie are cosmic rays events, that is high-energy
cosmic radiation hitting the detectors of the OSIRIS camera.

Little is known about Lutetia and Steins. Actually, very little is known
about asteroids in general. Out of the many millions of asteroids that
populate the Solar System, only a few have been observed so far from
near-by.

According to what we know so far, Steins and Lutetia have rather
different properties. Steins is relatively small, with a diameter of a
few kilometres. Lutetia is a much bigger object, about 100 kilometres in
diameter.

The Lutetia observation this month were aimed at pre-characterizing the
rotation direction of the asteroid. This can be done by the study of the
so-called 'light curve' of the asteroid - by analysing how the light
emitted by the observed object changes intensity for the observer, one
can deduce in what direction the object rotates. Scientists are now busy
in analysing the OSIRIS data to build the light curve of Lutetia.

Having concluded the Lutetia observations, Rosetta is now getting ready
for the next mission milestone: the swing-by of planet Mars. At the end
of February, the gravitational energy of the Red Planet will be used by
the spacecraft to get accelerated and then pushed, like a stone in a
sling-shot, on a trajectory towards Earth for the following gravity
assist manoeuvre in November 2007.

In the meantime Rosetta continues to provide new emotions as this
incredible spacecraft, travelling through the Solar System as a cosmic
'billiard ball', collects data and images of the objects on its way.
 
Note to editors
 
Asteroid 2867-Steins will be visited again by Rosetta on 5 September
2008 from 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. On 10 July 2010
Rosetta will pay its second visit to asteroid 21-Lutetia, passing within
about 3000 kilometres of it, at a speed of about 15 kilometres per second.

Rosetta will gather unprecedented data 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.

 
For more information
 
Rita Schulz, ESA Rosetta Project Scientist
Email: rita.schulz _at_ esa.int

Gerhard Schwehm, ESA Rosetta Mission Manager
Email: gerhard.schwehm _at_ esa.int

Uwe Keller, OSIRIS Principal Investigator, Max-Planck-Institut fur Aeronomie
Email: KELLER _at_ linmpi.mpg.de
Received on Fri 26 Jan 2007 03:12:44 PM PST