NASA's Dawn spacecraft obtained this image of Vesta with its framing camera on July 9, 2011. It was taken from a distance of about 26,000 miles (41,000 kilometers) away from the protoplanet Vesta. Each pixel in the image corresponds to roughly 2.4 miles (3.8 kilometers). (Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA)
On Saturday, controllers at the Jet Propulsion Laboratory in Pasadena received an indication they had been waiting for from the Dawn spacecraft. Dawn had successfully entered orbit around the astroid Vesta marking the first time a spacecraft had entered orbit around an object in the Asteroid Belt.
Vesta is a very large asteroid with an average diameter of about 529 kilometers, about 330 miles. This gives surface area of about 879,100 square kilometers and a volume of 77,510,000 cubic kilometers. Although Vesta is classified as an asteroid, part of an August 2006 proposal from the International Astronomical Union would reclassify Vesta as a dwarf planet. This is the same proposal that reclassified Pluto as a dwarf planet.
Launched aboard a Delta II rocket in September of 2007, Dawn has utilized an innovative ion propulsion drive, based on the Deep Space 1 ion drive, as well as a gravity assist from Mars to reach Vesta in the Asteroid Belt. To provide power to the ion drive and other on-board systems, the spacecraft has two very large solar arrays stretching almost 20 meters from tip to tip. This is enough surface area to produce more than 10 kW of power at 1 AU and over 1 kW of power within the Asteroid Belt. Dawn has a suite of 4 science instruments: a Framing Camera to provide imaging, a Visible and Infrared Spectrometer for the production of spectral images, a Gamma Ray and Neutron Spectrometer (GRaND) to measure the abundances of elements on the surface, and an instrument that provides highly accurate measurements of the spacecraft’s orbit allowing for a mapping of the gravity field. Dawn will remain in orbit around Vesta for approximately 1 year before engaging its ion drive once again and heading for the dwarf planet Ceres which also lies in the Asteroid Belt.
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