In late 2007 the Dawn mission spacecraft launched and began the 1.8 billion mile journey to the giant asteroid Vesta, which it reached in 2011. It was the first spacecraft to orbit a main-belt asteroid. In March 2015 it completed another 990 million miles to the dwarf planet Ceres and was the first spacecraft to orbit a dwarf planet, just ahead of the New Horizons mission that went to Pluto. The Dawn mission seeks to unlock some of the mysteries of planetary formation by studying these two asteroids that took different evolutionary paths.
Thousands of small bodies orbit the Sun in the asteroid belt—a large region between the orbits of Mars and Jupiter. They formed at the same time and in similar environments as those that grew to be the rocky planets of the inner solar system or bodies like the large icy moons of the outer solar system. Vesta is a dry object resembling a rocky planet like Earth, and Ceres is more like an icy moon. Ceres is almost twice the size of Vesta and has a primitive surface containing water-bearing minerals.
The mission’s namesake, Dawn, is symbolic. Vesta and Ceres date back to the time when the solar system was forming and the sun’s rays were scattered by the dust of the protoplanetary nebula. The Dawn mission hopes to use the information it gathers to provide breakthroughs in our knowledge of how the solar system formed.
The Science, Technology and Business Division will have NASA scientist Lucy McFadden, Co-Investigator of the Dawn mission, as the next speaker in our NASA/Goddard lecture series. Her talk, “Dawn: A Journey to the Beginning of the Solar System,” will be Thursday, November 19, 2015, from 11:30 a.m. – 12:30 p.m. in the Mary Pickford Theater on the third floor of the Library’s James Madison Memorial Building.
This post was authored by science reference librarian Stephanie Marcus, who coordinates the NASA Goddard lectures series at the Library.