The mini-planet Vesta faced a series of cosmic bombardment early in its formation, according to astronomers, and it now seems those impacts may be responsible for one of the mini-planet’s large stash of carbon.
According to a newly published study, a team led by Vishnu Reddy of the Max Planck Institute for Solar System Research in Lindau, Germany, the mini-planet’s carbon — which litters the rims of its craters — is the result of asteroids pummeling the surface.
The team, which spent months mapping the surface, says Vesta’s surface is marked by material as black as coal, much of which rests on and around craters. The study is the first to examine the rare feature and it required using NASA’s Dawn spacecraft to examine the remarkable, dark-as-coal material that speckles the surface of the giant asteroid.
“First, we created a map showing the distribution of dark material on Vesta using the framing camera data and found something remarkable,” said Lucille Le Corre from the Max Planck Institute for Solar System Research, one of the lead authors of the study.
According to the team, dark material was preferentially spread around the edges of the giant impact basins in the southern hemisphere of Vesta suggesting a link to one of the two large impact basins. Closer examination showed that the dark material was most likely delivered during the formation of the older Veneneia basin when a slow impacting asteroid collided with Vesta.
Researchers say the study could shed additional insight into how life came to be on Earth. Carbon, the main building block for life, is seen as a key element for astronomers searching for signs of life on other planets, including Mars. The same delivery system could have brought one of the essential building blocks of life to Earth, possibly loading Earth with enough carbon for millions of years.
Vesta is remarkable in many respects. The massive chunk of rock is the second-most-massive asteroid after the dwarf planet Ceres, and comprises an estimated 9 percent of the mass of the asteroid belt. Similar to other protoplanets, Vesta underwent complete melting approximately 4.5 billion years ago, however, most of the volcanic activity on Vesta is thought to have ceased within a few million years. The resulting cooling makes it a time capsule from the early solar system, providing astronomers with a rare glimpse of the inhabitants of the early solar system. NASA’s Dawn observations of Vesta have shown a surface with diverse brightness variations and surface composition. There is bright material on Vesta that is as white as snow and dark material on Vesta as black as coal.
The study is a major accomplishment for NASA’s Dawn spacecraft. The Dawn spacecraft orbited Vesta for more than a year, departing in September 2012. Dawn is now on its way to the dwarf planet Ceres, and will arrive in early 2015, according to NASA. The Dawn mission to Vesta and Ceres is managed by NASA’s Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, for NASA’s Science Mission Directorate, Washington.
The study was published in the journal Icarus.