A scientist team from NASA’s Dawn has observed that delivery of hydrous materials to Vesta was through clusters of small dust particles which occupied the Solar System during an epoch.
This process of delivery to Vesta, which is a giant-sized asteroid, seems to differ from the process in which hydrous materials were delivered to the moon and also to form the oceans on the Earth. The Dawn team, including Maria Cristina De Sanctis, will present its findings in Madrid on the 26 of September, Wednesday, at the European Planetary Science Congress.
Maria Cristina De Sanctis from the Institute of Astrophysics and Space Planetology in Rome, along with her team, analyzed Dawn’s infrared (VIR) mapping and visible spectrometric data which showed presence of hydroxyl in large concentrations in specific regions on Vesta. The hydroxyl concentration is evidence for presence of the Oppia crater, and also ancient terrains that are highly cratered. Hydroxyl concentrations were either absent or sparsely distributed around young impact craters with large size. This scenario suggests that hydroxyl delivery is not a continuous process.
On the Moon, hydroxyl is delivered through a process of interaction between the lunar regolith and protons from the solar winds. This process is said be a continuous process, and maximum hydroxyl concentrations are found in very cold regions of the permanently shadowed crater and near the lunar poles. The hydroxyl concentration on Vesta, on the other hand, does not depend on cold temperatures or significant shadowing, and is also stable over a time period. All these show that short-term processes are not involved in the origin of hydroxyl concentrations on Vesta.
Source: http://www.epsc2012.eu/