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Mercredi, 07 Décembre 2011 15:20

Rainbow Map of Giant Asteroid Shows Planet-Like Features

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Rainbow Map of Giant Asteroid Shows Planet-Like Features

By Mark Brown, Wired UK

This rainbow-colored map of the asteroid Vesta, obtained by NASA’s Dawn spacecraft, offers proof that the pumpkin-shaped rock is more like a terrestrial planet than most of its asteroid belt siblings.

The different colors in the image represent the various rock types in Vesta’s southern hemisphere. The probe’s framing camera — built by the Max Planck Institute for Solar System Research and the German Aerospace Center — picks up the wavelengths of radiation emitted from different minerals.

The green-colored areas, for example, indicates wavelengths at 750 nanometers divided by 920 nanometers, suggesting the presence of the iron-rich mineral pyroxene.

This all goes to show that Vesta is a diverse object with different cosmic ingredients and well-separated layers. This bolsters claims that Vesta is a protoplanet — an embryonic world that might have become a major planet if it wasn’t trapped in the lethal asteroid belt.

“The distinct compositional variation and layering that we see at Vesta appear to derive from internal melting of the body shortly after formation, which separated Vesta into crust, mantle and core,” said Carol Raymond, Dawn’s deputy principal investigator at NASA’s Jet Propulsion Laboratory, in a press release. “Vesta’s iron core makes it special and more like terrestrial planets than a garden-variety asteroid.”

The colorful image that Dawn sent back centers on Rheasilvia, an impact basin that’s 290 miles wide. A central mound — Rheasilvia Mons — reaches 14 miles into space, making it almost three times as high as Everest and the tallest known mountain in the solar system.

The $466-million Dawn spacecraft arrived at Vesta in July this year. It will study the tiny world for a year before moving on to Ceres — the largest body in the asteroid belt and another protoplanet.

Image: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA [high-res]



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