Dawn spacecraft motors toward asteroid Vesta

Posted by David Eicher
on Wednesday, May 11, 2011

There’s exciting news from the solar system — NASA’s Dawn spacecraft, which is set to orbit the asteroid 4 Vesta, has captured images of the big rock on its approach. The photos, released today, show the asteroid, which measures 330 miles (530 kilometers) across, as a small disk from a distance of 752,000 miles (1.2 million km).

When Dawn begins orbiting Vesta July 16, it will collect data from an altitude of only 1,700 miles (2,700 km), imaging the famous asteroid so that planetary scientists can create detailed topographic maps. The spacecraft will then decrease altitude to a mere 120 miles (200 km) to study particular areas. In 2015, the same year as New Horizon’s arrival at Pluto, Dawn will reach its second asteroidal target, 1 Ceres.

The first new image shows Vesta as a raw, unprocessed clump of pixels set in front of a stellar background. The second, a processed image, shows the asteroid and star background more deeply, along with an inset showing an enlargement of Vesta.

Vesta is of great interest to amateur astronomers as one of the brightest and largest asteroids and also because a whole family of meteorites found on Earth, the so-called HED group (encompassing the Howardites, Eucrites, and Diogenites), originated from Vesta, blasted off the asteroid by impacts long ago. This group includes some famous falls — for example, the Tataouine meteorite in southern Tunisia. In March, I was privileged to go with a group of Astronomy’s readers to pick up pieces of this meteorite from the strewn field.

For more on Dawn’s approach, see http://www.nasa.gov/dawn

For more on the Tunisia trip, see: http://www.astronomy.com/Vesta

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