April 23, 2009

Solar wind found to age asteroid surfaces

A European Space Agency-led team of astronomers has determined the rapid space weathering seen on asteroid surfaces is most likely caused by the solar wind.

The study led by ESA scientist Pierre Vernazza reveals that solar wind ages and reddens asteroid surfaces much more quickly than previously thought -- in less than a million years. The scientists said their finding will help astronomers relate the appearance of an asteroid to its actual history and identify any after effects of a catastrophic impact with another asteroid.

It has long been known that asteroid surfaces alter in appearance with time, but the actual processes of the space weathering and the timescales involved were controversial.

The new study -- using the European Southern Observatory's New Technology Telescope and the Very Large Telescope, both in Chile, as well as telescopes in Spain and Hawaii -- solved the puzzle.

When two asteroids collide, they create a family of fragments with fresh surfaces, the researchers said. The astronomers found that newly exposed surfaces are quickly altered and change color in less than a million years -- a very short time compared to the age of the solar system.

The research that included Richard Binzel of the Massachusetts Institute of Technology, Alessandro Rossi of Italy's Institute of Information Science and Technologies and Marcello Fulchignoni and Mirel Birlan, both of the Paris Observatory, appears in the journal Nature.