[FPSPACE] Fw: ESA: Rosetta's Blind Date with Asteroid Lutetia

[LARRY KLAES]

Sent via BlackBerry by AT&T

-----Original Message-----
From: "AAS Press Officer Dr. Rick Fienberg" <rick.fienberg at aas.org>
Date: Tue, 15 Jun 2010 15:32:28 
To: <Rick.Fienberg at aas.org>
Subject: ESA: Rosetta's Blind Date with Asteroid Lutetia

THE FOLLOWING RELEASE WAS RECEIVED FROM THE EUROPEAN SPACE AGENCY'S
 SPACE SCIENCE PORTAL IN NOORDWIJK, THE NETHERLANDS, AND IS FORWARDED
 FOR YOUR INFORMATION. (FORWARDING DOES NOT IMPLY ENDORSEMENT BY THE
 AMERICAN ASTRONOMICAL SOCIETY). Rick Fienberg, AAS Press Officer:
 rick.fienberg at aas.org, +1 202-328-2010 x116.
 
 15 June 2010
 
 ** Contact data are at the end. **
 
 Article and images:
 http://www.esa.int/esaSC/SEM9VRQVEAG_index_0.html
 
 ROSETTA'S BLIND DATE WITH ASTEROID LUTETIA
 
 ESA's comet-chaser Rosetta is heading for a blind date with asteroid
 Lutetia. Rosetta does not yet know what Lutetia looks like, but
 beautiful or otherwise the two will meet on 10 July.
 
 Like many first dates, Rosetta will meet Lutetia on a Saturday night,
 flying to within 3,200 km of the space rock. Rosetta started taking
 navigational sightings of Lutetia at the end of May so that ground
 controllers can determine any course corrections required to achieve
 their intended flyby distance.
 
 The close pass will allow around 2 hours of good imaging. The
 spacecraft will instantly begin beaming the data back to Earth and the
 first pictures will be released later that evening.
 
 Rosetta flew by asteroid Steins in 2008 and other space missions have
 encountered a handful of asteroids. Each asteroid has proven to be an
 individual, and Lutetia is expected to continue the trend.
 
 For a start, no one knows what it looks like. Orbiting in the main
 belt of asteroids between Mars and Jupiter, it appears as a single
 point of light to ground telescopes. The continuous variation in its
 brightness makes it clear that Lutetia is rotating and has an uneven
 surface. These observations allow astronomers to estimate its shape
 and size, but their determinations all differ.
 
 Initially it was thought that Lutetia is around 95 km in diameter but
 only mildly elliptical. A more recent estimate suggests 134 km, with a
 pronounced elongation. Rosetta will tell us for certain and will also
 investigate the composition of the asteroid, wherein lies another
 mystery.
 
 By any measure, Lutetia is quite large. Planetary scientists believe
 that it is a primitive asteroid left on the shelf for billions of
 years because no planet consumed it as the Solar System formed.
 Indeed, most measurements appear to back this picture, making the
 asteroid out to be a 'C-type', which contains primitive compounds of
 carbon.
 
 However, some measurements suggest that Lutetia is an 'M-type', which
 could mean there are metals in its surface. "If Lutetia is a metallic
 asteroid then we have found a real winner," says Rita Schulz, ESA
 Rosetta Project Scientist.
 
 That is because although metallic asteroids do exist, they are thought
 to be fragments of the metallic core of larger asteroids that have
 since been shattered into pieces. If Lutetia is made of metal or even
 contains large amounts of metal, Dr. Schulz says that the traditional
 asteroid classification scheme will need rethinking. "C-class
 asteroids should not have metals on their surfaces," she says.
 
 Asteroid science stands to gain once this observational conundrum is
 resolved because Rosetta's data will provide a valuable collection of
 'ground truths' that can be used to resolve conflicting ground-based
 observations not just for Lutetia but for other asteroids as well.
 
 For 36 hours around the moment of closest approach, Rosetta will be in
 almost continuous contact with the ground. The only breaks will come
 as Earth rotates and engineers have to switch from one tracking
 station to another.
 
 Good contact is essential because the uncertainties in the asteroid's
 position and shape may demand last minute fine-tuning to keep it
 centered in Rosetta's instruments during the flyby. "The skeleton of
 the operation is in place, and we have the ability to update our plans
 at any time," says Andrea Accomazzo, ESA Rosetta Spacecraft Operations
 Manager.
 
 Stay in touch with the flyby as it happens by visiting the Rosetta blog:
 http://webservices.esa.int/blog/blog/5/
 
 ESA PIO Source:
 Markus Bauer
 ESA Communication and Knowledge Department
 +31 71 56 56799
 markus.bauer at esa.int
 
 ------------------------------------------------------------------------
 If you do not wish to receive press releases that are forwarded to the
 news media by the American Astronomical Society, please unsubscribe by
 replying accordingly to any incoming press release, or send e-mail to
 rick.fienberg at aas.org. Requests for referrals to experts on astronomy
 and space science should be sent to the same address. Rick Fienberg,
 AAS Press Officer, +1 202-328-2010 x116.