A young crater that's about nine miles (15 km) across scars the surface of Vesta, one of the largest asteroids, in this view from the Dawn spacecraft. Large boulders that were blasted out by the impact that created the crater are scattered around its rim. Dawn will depart Vesta in early September and head toward the largest asteroid, Ceres, with arrival in early 2015. [NASA/JPL/UCLA/MPS/DLR/IDA]
Vesta is one of the largest asteroids — a layered ball of rock and metal more than 300 miles in diameter. It’s also something of a scientific conundrum, notes Carol Raymond, a scientist with a mission called Dawn.
RAYMOND: We’ve had pieces of Vesta under study in the laboratory for decades, but are now only getting out to know the parent body.
For decades, scientists have suspected that several groups of meteorites came from Vesta — blasted from Vesta’s surface when it was hit by another asteroid. The composition of the meteorites seemed to match what astronomers could see of Vesta through telescopes. Until Dawn entered orbit around Vesta last year, though, there was little way to confirm that idea.
But Dawn’s observations strongly support it. In fact, they’ve even narrowed down the likely site of the impact that chipped off the meteorites — a large basin at the asteroid’s south pole. The energy of the impact caused the asteroid’s crust to rebound, building a mountain that towers 13 miles above the basin floor.
The combination of the meteorites and Dawn’s observations will help scientists better understand Vesta’s composition, structure, and history. And since Vesta is one of the oldest surviving “leftovers” from the formation of the planets, the combination will also provide new insights into the process that gave birth to the planets — including our own Earth.
Dawn’s time at Vesta is almost up, though; more about that tomorrow.
Script by Damond Benningfield, Copyright 2012
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