EMBARGOED UNTIL: Wednesday 13 February ... - Universität Bern
EMBARGOED UNTIL: Wednesday 13 February ... - Universität Bern
EMBARGOED UNTIL: Wednesday 13 February ... - Universität Bern
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Rector’s Office<br />
Communication Office<br />
Press release<br />
<strong>EMBARGOED</strong> <strong>UNTIL</strong>: <strong>Wednesday</strong> <strong>13</strong> <strong>February</strong> 20<strong>13</strong>, 7:00 p.m. CET<br />
<strong>13</strong> <strong>February</strong> 20<strong>13</strong><br />
<strong>Bern</strong> computer simulation helps to better understand the origin of our solar<br />
system<br />
Simulations boost the significance of image and measurement data from space missions:<br />
based on the example of an asteroid, <strong>Bern</strong>ese astrophysicist Martin Jutzi shows how collisions<br />
with other celestial bodies can be reconstructed and that even the internal structure of socalled<br />
protoplanets can be described. These models help to understand the development of<br />
our solar system. The study appears as today’s cover story in the journal Nature.<br />
Four and a half billion years ago, dust particles in a giant, dusty gas cloud combined to form increasingly<br />
large clumps. These collided, aggregated and thus grew into planets. Between the planetary orbits<br />
of Mars and Jupiter, however, hundreds of thousands of smaller fragments remained. They<br />
formed the so-called asteroid belt and hardly changed their composition since then. Asteroids thus<br />
contain an inestimable amount of information on the origin of our solar system. In research, particular<br />
attention is paid to an asteroid called Vesta: with a diameter of around 500 kilometres, it is one of the<br />
three largest asteroids and considered to be a protoplanet. Moreover, it is the only known asteroid to<br />
have an earth-like structure – with a core, mantle and crust.<br />
Computer simulation reconstructs collisions between asteroids<br />
Using a three-dimensional computer simulation, Martin Jutzi from the Center for Space and Habitability<br />
(CSH) at the University of <strong>Bern</strong> has now accurately reconstructed how Vesta collided with other<br />
asteroids twice over a billion years ago. The models show that the protoplanet owes its elliptical shape<br />
to these collisions and that they also scarred its surface structure. The simulations also enable detailed<br />
conclusions on the composition and properties of Vesta’s interior to be drawn for the first time,<br />
which helps us to better understand the evolution of the solar system. After all, the formation of<br />
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Communication Office<br />
Hochschulstrasse 4<br />
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Tel. +41 031 631 80 44<br />
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planets largely depends upon collisions between celestial bodies. «Our method facilitates especially<br />
informative analyses of image and measurement data from space missions,» says Martin Jutzi. The<br />
study, which was conducted in collaboration with researchers from the EPFL, France and the USA,<br />
features as the cover story in today’s issue of Nature.<br />
Models uncover hidden secrets<br />
Previously, observations with the Hubble Space Telescope provided initial evidence of a giant crater at<br />
Vesta’s south pole. Then, in 2007, NASA’s «Dawn» probe began its space voyage into the solar system’s<br />
past. Starting in the summer of 2011, it closely orbited Vesta for one year. Images from within<br />
the visible range as well as other measurement data provided information on the asteroid’s topography<br />
and the composition of the minerals that are visible on its surface. It became apparent that the<br />
crater observed by Hubble at Vesta’s south pole is actually composed of two partially overlapping basins.<br />
Based on this information, the computer simulations by Jutzi’s team now demonstrate exactly how two<br />
consecutive impacts of celestial bodies led to the formation of the observed overlapping basins, which<br />
almost span the entire southern hemisphere of Vesta. The models show the size (66 and 64 kilometres<br />
in diameter), velocity (5.4 kilometres per second) and the impact angle of the bodies that collided<br />
with Vesta. This reveals a lot about the properties of the objects that were near the protoplanet a billion<br />
years ago.<br />
The final images of the simulations closely resemble the shape and topography of Vesta’s southern<br />
hemisphere as observed by the Dawn mission. The models even accurately reproduce the spiralshaped<br />
structures inside the youngest crater which are visible on images from the Dawn mission.<br />
«This shows how reliable our method is,» rejoices Jutzi. The researchers assume that the models also<br />
provide information about previously hidden features of Vesta. For instance, the simulations reveal<br />
that the material exposed by the impacts comes from depths of up to 100 kilometres. «Based on the<br />
sort and distribution of this material we are able to precisely reconstruct the various inner layers of<br />
Vesta,» explains Philippe Gillet, Direktor des Earth and Planetary Science Laboratory der EPFL.<br />
«The fact that we can now look inside such protoplanets makes entirely new perspectives in the research<br />
on the history of our solar system possible,» says Jutzi.<br />
Further reading:<br />
M. Jutzi, E. Asphaug, P. Gillet, J.-A. Barrat, W. Benz: The structure of the asteroid 4 Vesta as revealed<br />
by models of planet-scale collisions, Nature, 14 <strong>February</strong> 20<strong>13</strong>, in print.<br />
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Contact people:<br />
Dr Martin Jutzi, Center for Space and Habitability (CSH), Universität <strong>Bern</strong><br />
+41 31 631 85 49 / martin.jutzi@space.unibe.ch<br />
Prof. Dr Philippe Gillet, Earth and Planetary Science Laboratory, EPFL<br />
+41 21 69 370 58 / philippe.gillet@epfl.ch<br />
Prof. Dr Willy Benz, Center for Space and Habitability (CSH), Universität <strong>Bern</strong><br />
+41 31 631 44 03 / willy.benz@space.unibe.ch<br />
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