NASA’s Dawn Discovers ‘Young’ Surface on Asteroid

    October 31, 2012
    Sean Patterson
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NASA announced today that data from its Dawn probe show the giant asteroid Vesta is constantly “stirring” its surface, presenting a “young” appearance. The type of weathering that occurs on airless bodies, such as the moon, does not alter Vesta’s surface in the same way.

Specifically, objects such as asteroids and the moon accumulate tiny metallic particles containing iron, which dulls their “fluffy” outer layer. Researchers using data from Dawn’s visible and infrared mapping spectrometer (VIR) found no accumulation of the particles on Vesta.

“Getting up close and familiar with Vesta has reset our thinking about the character of the uppermost soils of airless bodies,” said Carle Pieters, lead author of one of two Vesta studies published today in the journal Nature and a Dawn team member at Brown University. “Vesta ‘dirt’ is very clean, well mixed and highly mobile.”

When Vesta was first photographed, researchers were puzzled by its light and dark splotches. The brightness range on the asteroid is among the largest observed on rocky bodies in the solar system.

NASA stated that “bright rays” of young features on Vesta degrade rapidly into the background soil, mixed by continual small impacts. Also, Vesta’s unusually steep topography means landslides mix the surface as well.

The dark spots, which were originally thought to be the result of volcanic activity or high-speed impacts, have now been shown to be carbon-rich material from meteoroids. Researchers estimate, based on the amount of darkening, that around 300 asteroids with diameters between 0.6 to 6 miles likely hit Vesta in the past 3.5 billion years.

“This perpetual contamination of Vesta with material native to elsewhere in the solar system is a dramatic example of an apparently common process that changes many solar system objects,” said Tom McCord, lead author of the other study and a Dawn team member at Bear Fight Institute. “Earth likely got the ingredients for life – organics and water – this way.”

NASA’s Dawn probe was launched in September 2007 and entered orbit around Vesta in July 2011. Dawn left its orbit around Vesta last month and is currently on course for the dwarf planet Ceres.

  • Chris Landau

    Dear Brown University and Nature Magazine

    I do not think Vesta is stirring its “loose rock surface” because there is no loose rock surface. I think Dawn reshapes its surface by melting and flowing like two color chocolate boiling and mixing slowly over a low heat.I think Vesta is basaltic and glassy and that is why it has a high reflectivity. I also think the black spots are sulfides from its own internal heat,being ejected in volcanic points and in long chains or dike like features and not black, due to carbonaceous condrite impacts. Look at the patterns carefully. As Vesta is a low gravity world, with a much weaker gravity than even that of our moon, landslides are not reshaping Vesta, but heat generated from its interior certainly is obliterating half a crater here and there,but not the whole crater. The other half of the crater and crater rim is perfectly preserved. So landslides, due to non existent rubble, on half a crater, in a low gravity world, do not wash here. Please rethink and be more logical. You can do better.
    Chris Landau (geologist) November 3 2012