March 21, 2012
Dawn Spacecraft Reveals New Details Of Vesta
The space agency said its spacecraft shows new images and data of the diversity of Vesta's surface, revealing unusual geological features.
Dawn has found that some areas on the asteroid can be nearly twice as bright as others, which gives scientists clues about the asteroid's history.
"Our analysis finds this bright material originates from Vesta and has undergone little change since the formation of Vesta over 4 billion years ago," Jian-Yang Li, a Dawn participating scientist at the University of Maryland, College Park, said in a press release. "We're eager to learn more about what minerals make up this material and how the present Vesta surface came to be."
The bright areas can be anywhere between several hundred feet to about 10 miles across. NASA said that rocks crashing into the surface of Vesta seem to have exposed and spread this material.
The space agency said Dawn scientists did not expect such a wide variety of distinct dark deposits across its surface. This dark materials can appear dark gray, brown and red.
"One of the surprises was the dark material is not randomly distributed," David Williams, a Dawn participating scientist at Arizona State University, Tempe, said in a statement. "This suggests underlying geology determines where it occurs."
Scientists believe carbon-rich asteroids could have hit Vesta at speeds low enough to produce some of the smaller deposits without blasting away the surface.
NASA said higher-speed asteroids could have also hit Vesta's surface and melted the volcanic basaltic crust, darkening existing surface material.
"Some of these past collisions were so intense they melted the surface," Brett Denevi, a Dawn participating scientist at the Johns Hopkins University Applied Physics Laboratory in Laurel, Md, said in a statement.. "Dawn's ability to image the melt marks a unique find. Melting events like these were suspected, but never before seen on an asteroid."
Dawn, which launched in September 2007, is poised to reach its next destination in February 2015.
Image Caption: This image of a dark-rayed impact crater and several dark spots was obtained by NASA's Dawn spacecraft. Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/ASU [ More Images ]