Overview map of Vesta's southern hemisphere. The circles, diamonds, and stars show where the dark material occurs. The red line depicts the rim of the Veneneia basin, the black line the rim of the younger Rheasilvia basin. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
Data gleaned by NASA’s Dawn spacecraft during a year-long survey of asteroid Vesta have shown that impacting small asteroids delivered dark, carbonaceous material to the protoplanet.
These huge impacts not only altered Vesta’s shape, but also its surface composition.
Researchers report that large collisions between asteroids transferred carbonaceous material in the inner solar system, noting this observation in the November-December issue of the journal Icarus.
In the early days of our solar system, similar events may have provided the inner planets — such as Earth — with carbon. Carbon is an essential building block for organic molecules.
White as snow, black as coal
Vesta is remarkable in many respects.
With a diameter of approximately 530 kilometers, Vesta is the one of the few protoplanets in our solar system still intact today. Like 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, making it a time capsule from the early solar system.
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.
Vishnu Reddy from the Max Planck Institute for Solar System Research (MPS) and the University of North Dakota was the lead author of the newly issued Icarus paper.
The Dawn mission was launched some five years ago and entered orbit around Vesta on July 16th, 2011. But there’s more to come!
In 2015, Dawn will arrive at its second destination, the dwarf planet Ceres.
By Leonard David/DLR release