Asteroid Lutetia witness the birth of the earth

Celestial body originated in the innermost areas of the solar system

Asteroid Lutetia near a planet - artistic illustration © M. Kornmesser and N. Risinger ( / ESO
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The asteroid Lutetia may be a remnant of the same material from which Earth, Venus and Mercury once arose: this is the result of new observations of the Rosetta spacecraft and of various telescopes. Thus, the properties of the asteroid coincide with those of a rare meteorite species, which is thought to have formed in the innermost parts of the solar system.

Lutetia, too, may have started its existence there and would later have wandered out to its current position in the asteroid belt between Mars and Jupiter, the researchers report in the journal Icarus.

Astronomers determine composition of Lutetia

A team of astronomers from French and North American universities studied the unusual asteroid Lutetia in detail over a wide range of wavelengths to determine its composition. Data from the OSIRIS camera on ESA's Rosetta space probe, the New Technology Telescope (NTT) at ESO's La Silla Observatory in Chile, the NASA's Infrared Telescope Facility on Hawaii, and the Spitzer Space Telescope were combined to create the most comprehensive spectrum ever was won by an asteroid.

The researchers then compared the Lutetia spectrum with the spectra of various meteorites found on Earth and extensively studied in the laboratory. Only one type of meteorite, the so-called enstatite chondrites, agreed with Lutetia over the entire spectral range.

Enstatite chondrites consist of material from the time of origin of the solar system. It is believed that they formed near the young sun, and that this sort of object was one of the major ingredients in the formation of rocky planets, especially Earth, Venus, and Mercury. Also Lutetia should therefore not come from the main asteroid belt, where it is now, but from an area much closer to the sun. display

Asteroid Lutetia - Taken by Rosetta ESA 2010 MPS for OSIRIS Team MPS / UPD / LAM / IAA / RSSD / INTA / UPM / DASP / IDA

How did Lutetia escape into the asteroid belt?

But how did Lutetia escape from the inner solar system and enter the asteroid belt? "Asks Pierre Vernazza, ESO's lead author of the new study.

Astronomers have estimated that less than two percent of the objects that originate from the area where the Earth was formed have migrated into the asteroid belt. The majority of these bodies from the inner solar system were, according to the scientists, captured within a few million years by the emerging young planets. However, some of the larger objects with diameters of 100 kilometers or more may have been thrown out and found themselves in safer orbits further away from the sun in the long term.

Lutetia as an intruder

Lutetia, which has a diameter of almost 100 kilometers, could also have been torn from its original orbit and thus from the inner parts of the solar system by the flyby of one of the rock planets. An encounter with the young Jupiter during his migration to his current position could also have had a significant impact on Lutetia's orbit.

We assume that Lutetia has undergone such a rail change. It arrived as an intruder in the main asteroid belt and was preserved there for four billion years, "says Vernazza.

Asteroid gives researchers R tsel

Previous studies of their color and surface structure have shown that Lutetia and the uttermost unusual member of the asteroid genus still give astronomers some riddles. Surveys have shown that comparable asteroids are rare and make up less than one percent of the main asteroid core. The new results now explain why Lutetia is so different - it is one of the rare "survivors" of the source material that formed the rock planets.

Lutetia should represent the largest collection of this kind of original material. This makes it the ideal destination for future missions that could bring rock samples to Earth. This material could be used to study in detail the formation of rocky planets such as our earth, "concludes Vernazza. (Icarus, 2011)

(Max Planck Institute for Astronomy / ESO Science Outreach Network, 14.11.2011 - DLO)