The giant asteroid Vesta is constantly stirring its outermost layer, according to data from NASA's Dawn mission that show that a form of weathering that occurs on the moon and other airless bodies we've visited in the inner solar system does not alter Vesta's outermost layer in the same way.
Carbon-rich asteroids have also been splattering dark material on Vesta's surface over a long span of the body's history. Over time, soils on Earth's moon and asteroids such as Itokawa have undergone extensive weathering in the space environment. Scientists see this in the accumulation of tiny metallic particles containing iron, which dulls the fluffy outer layer. Dawn's visible and infrared mapping spectrometer (VIR) and framing camera detected no accumulation of such tiny particles on Vesta, and this particular protoplanet, or almost-planet, remains bright and pristine.
Launched in 2007, Dawn spent more than a year investigating Vesta. It departed in September 2012 and is currently on its way to the dwarf planet Ceres.
An image from NASA's Dawn spacecraft features the distinctive crater Canuleia on the giant asteroid Vesta. Canuleia, about 6 miles in diameter, is distinguished by the rays of bright material that streak out from it. There is also a more subdued unnamed crater of about the same size to the northeast. A comparison of these two craters illustrates how freshly excavated materials on Vesta appear quite different from background soils. The image was taken by Dawn's framing camera on Oct. 20, 2011, from an altitude of about 420 miles. Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/PSI/Brown
"Dawn's data allow us to decipher how Vesta records fundamental processes that have also affected Earth and other solar system bodies," said Carol Raymond, Dawn deputy principal investigator at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "No object in our solar system is an island. Throughout solar system history, materials have exchanged and interacted."
Nevertheless, the bright rays of the youngest features on Vesta are seen to degrade rapidly and disappear into background soil. Scientists know frequent, small impacts continually mix the fluffy outer layer of broken debris. Vesta also has unusually steep topography relative to other large bodies in the inner solar system, which leads to landslides that further mix surface material.
"Getting up close and familiar with Vesta has reset our thinking about the character of the uppermost soils of airless bodies," said Carle Pieters, one of the lead authors and a Dawn team member based at Brown University, Providence, R.I. "Vesta 'dirt' is very clean, well mixed and highly mobile."
Early pictures of Vesta showed a variety of dramatic light and dark splotches on Vesta's surface. These light and dark materials were unexpected and now show the brightness range of Vesta is among the largest observed on rocky bodies in our solar system.
Dawn scientists suspected early on that bright material is native to Vesta. One of their first hypotheses for the dark material suggested it might come from the shock of high-speed impacts melting and darkening the underlying rocks or from recent volcanic activity. An analysis of data from VIR and the framing camera has revealed, however, that the distribution of dark material is widespread and occurs both in small spots and in diffuse deposits, without correlation to any particular underlying geology. The likely source of the dark material is now shown to be the carbon-rich material in meteoroids, which are also believed to have deposited hydrated minerals from other asteroids on Vesta.
To get the amount of darkening we now see on Vesta, scientists on the Dawn team estimate about 300 dark asteroids with diameters between 0.6 to 6 miles (1 and 10 kilometers) likely hit Vesta during the last 3.5 billion years. This would have been enough to wrap Vesta in a blanket of mixed material about 3 to 7 feet (1 to 2 meters) thick.
"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, the other lead author and a Dawn team member based at the Bear Fight Institute, Winthrop, Wash. "Earth likely got the ingredients for life - organics and water - this way."
Published in Nature.
- PHYSICAL SCIENCES
- EARTH SCIENCES
- LIFE SCIENCES
- SOCIAL SCIENCES
Subscribe to the newsletter
Stay in touch with the scientific world!
Know Science And Want To Write?
- The Five Stages Of A Dying Theory
- Something is wrong in the Arctic
- Is The X(5568) A True Resonance ?
- Order Patterned With Chaos - How Climate Is Predicted For Decades - With Exact Forecasts Only For Days
- Neanderthals: Not So Dumb
- Should Pregnant Women Be Concerned About BPA?
- Anomaly! Book Presentation At CERN On November 29
- "See my Debunked - The world will end because the Bible (or some other sacred book) says soIt's..."
- " Yo Robert, can you debunk this: http://www.express.co.uk/news/weird/740551/end-of-world-apocalypse..."
- "Oh okay maybe they got upset in the same way you did. You could try pointing them towards my Nibiru..."
- "So you can guarantee to me that this is not real yeah thats all i want for this not to be real..."
- Credit NHL for Smart, Safe Concussion Strategy
- Don't Drive 'Gene Drives' Into a Ditch
- Public Citizen Wants You Dead- Not Bacteria
- Pfizer's Centrum Silver Multivitamins Contain Pesticide, Paint & Glass
- Paper Scandal at Science? Microbeads Lying in the Weeds, and a Stolen Computer
- Pfizer's Centrum Silver Multivitamins Contain Pesticide, Paint, and Glass