Dawn Mission Data Offers New Evidence On Vesta Asteroid's History

Lee Rannals for redOrbit.com – Your Universe Online

A new paper published in the journal Nature rewrites the history of the giant asteroid Vesta, which was recently visited by NASA’s Dawn mission.

It was during the Dawn mission that the spacecraft used its visible and infrared mapping spectrometer instrument to map out the surface of the asteroid, leading scientists to the belief that Vesta’s formation followed the script that rocky planets followed, where the mineral olivine should concentrate in the mantle.

However, some new findings combat this theory.

“Here we report that olivine is indeed present locally on Vesta’s surface but that, unexpectedly, it has not been found within the deep, south-pole basins, which are thought to be excavated mantle rocks,” the researchers wrote in the journal.

Scientists said the observations of craters in Vesta’s southern hemisphere that exposed the lower crust should have found mineral olivine, but it was unsuccessful. Instead, the team discovered signatures of olivine in the surface material in the northern hemisphere.

“The lack of pure olivine in the deeply excavated basins in Vesta’s southern hemisphere and its unexpected discovery in the northern hemisphere indicate a more complex evolutionary history than inferred from models of Vesta before Dawn arrived,” Maria Cristina De Sanctis, Dawn co-investigator and VIR leader at the National Institute for Astrophysics in Rome, Italy, said in a statement.

Carol Raymond, Dawn’s deputy principal investigator at NASA’s Jet Propulsion Laboratory, Pasadena, CA, said the latest findings are making scientists test out different hypotheses about Vesta’s origin.

“They also show us what additional information we can learn by going into orbit around places like Vesta to complement the bits that come to us as meteorites or observations from long distances,” Raymond said.

Dawn wrapped up its data collection of the asteroid back in September 2012, and the NASA spacecraft is now on its way towards the dwarf planet Ceres. This dwarf planet is the biggest member of the main asteroid belt between Mars and Jupiter. NASA says Dawn will be arriving at its second destination sometime in early 2015.

Although Dawn has been hurtling itself towards Ceres for over a year now, data about Vesta has continued to surface from its original mission. In December, scientists said that gullies found on the asteroid could have been formed by liquid water.

This past September, researchers at the European Planetary Science Congress (EPSC) 2013 in London released an atlas of Vesta images captured during the Dawn mission. The atlas was comprised of maps created from mosaics of 10,000 images from Dawn’s framing camera at an average altitude of about 130 miles.