NASA’s Dawn spacecraft has discovered new features on Vesta

The Canuleia crater on Vesta
The Canuleia crater on Vesta

NASA‘s Dawn spacecraft has revealed some new and unexpected details on the surface of the giant asteroid Vesta. The images and data captured shows the diversity of Vesta‘s surface, and reveal unusual geologic features. Some never previously seen on a asteroid.

Being one of the brightest objects in the solar system, Vesta is the only asteroid in the main belt between Mars and Jupiter visible to the naked eye from Earth. Scientists have previously seen brightness variations in previous images of Vesta captures with NASA’s Hubble Space Telescope, but the new images captured by the Dawn spacecraft found that some areas on Vesta can be nearly twice as bright as others. This could potentially reveal clues about the asteroid’s history.

Bright areas appear everywhere on Vesta but are most predominant in and around craters. The areas can vary from several hundred feet, to around 10 miles across. “Our analysis finds this bright material originates from Vesta and has undergone little change since the formation of Vesta over 4 billion years ago”, said Jian-Yang Li, a Dawn participating scientist at the University of Maryland, College Park. “We’re eager to learn more about what minerals make up this material and how the present Vesta surface came to be.”

Dark materials on Vesta can appear dark gray, brown and red, and sometimes appear as small, well-defined deposits around impact craters. They also can appear as larger regional deposits, like those surrounding impact craters. What surprise the scientists, is that it seems the dark material is not randomly distributed. “This suggests underlying geology determines where it occurs”, said David Williams, a Dawn participating scientist at Arizona State University, Tempe.

The dark materials seem to be related to impacts and their aftermath. Scientists theorize carbon-rich asteroids could have hit Vesta at speeds low enough to produce some of the smaller deposits without blasting away the surface.

Higher-speed asteroids also could have hit the asteroid’s surface and melted the volcanic basaltic crust, darkening existing surface material. That melted conglomeration appears in the walls and floors of impact craters, on hills and ridges, and underneath brighter, more recent material called ejecta, which is material thrown out from a space rock impact.

Vesta‘s dark materials suggest the giant asteroid may preserve ancient materials from the asteroid belt and beyond, possibly from the birth of the solar system. “Some of these past collisions were so intense they melted the surface”, said Brett Denevi, a Dawn participating scientist at the Johns Hopkins University Applied Physics Laboratory in Laurel, Md. “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’s ambitious exploration of Vesta has been going beautifully”, said Marc Rayman, Dawn chief engineer at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, Calif. “As we continue to gather a bounty of data, it is thrilling to reveal fascinating alien landscapes.” 

Dawn launched in September 2007. It will reach its second destination, Ceres, in February 2015.

Press Release