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Space rock offers clues?on early solar system

In the September edition of Discover, Tim Folger writes about the Dawn spacecraft's sojourn to Vesta, one of the largest asteroids, which is floating in the asteroid belt between Mars and Jupiter. Dawn reached its destination in July 2011 and has since been mapping the 311-mile-wide space rock's surface.

There are a few notable landscape features, including a crater with a 14-mile-high peak at its center. But why fly halfway across the solar system to survey a giant hunk of cosmic dust? Because Vesta is a relic of the early days of the solar system, when huge chunks of ice and rock were drifting around the sun's orbit. Some of this debris eventually globbed together to form terrestrial worlds, but Vesta, which was too close to Jupiter's immense gravity, stalled out and never made it to full planethood.

By surveying Vesta, scientists hope to better understand the makeup of the early solar system and how our planet came to be. Its Vesta mission completed, Dawn has moved on toward its next destination, 38 million miles away: the dwarf planet Ceres.

- Washington Post