Four and a half years ago a Delta II rocket arced high over Florida, carrying what has proven to be one of the most fantastic unmanned explorers ever launched from our planet: Dawn.
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| September 27, 2007: As the sun rises, Dawn is carried aloft by a Delta II rocket at pad 17-B, Cape Canaveral Air Force Station. |
Dawn’s mission is to explore the asteroid belt, with particular focus on two objects: the asteroid Vesta, and the so-called “minor planet” Ceres. Vesta’s dimensions are roughly 359 by 348 by 285 miles, while Ceres is much larger: nearly as big across as the state of Texas, and an object that may bear a weak atmosphere. Both objects are believed to have formed early in the inception of our solar system. Despite that similarity, the objects are vastly different entities – the very reason they were selected for exploration.
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| In this artist concept, Dawn is shown traveling among the asteroids. Each of the solar panels providing power measures 8 feet by 27 feet. |
While Ceres will fall under Dawn’s gaze in 2015, the explorer arrived at Vesta in the middle of 2011, and has been hard at work ever since. On April 25, some of Dawn’s intriguing findings were presented by NASA’s Jet Propulsion Laboratory in Pasadena, CA.
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| NASA's Dawn spacecraft approaches orbit around the giant asteroid Vesta on July 24, 2011. This photo was taken from a distance of about 3,200 miles. |
The surface of Vesta contains a wide variety of composition and patterns – including material that was at one time molten and beneath the asteroid’s surface. There are rocks apparently fused by collisions encountered in the asteroid’s travels, as well as smooth surface areas described by JPL scientists as “pond-like.”
Vesta is a frigid asteroid, with Dawn measuring temperatures ranging from minus 10 to minus 150 Fahrenheit – demonstrating how much of a role illumination from the sun can alter temperatures without atmospheric considerations.
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| A relatively new crater spreads approximately nine miles across the surface of Vesta. Boulders and other debris around the crater are believed to have originated deep beneath the asteroid’s surface, cast outward upon impact with the object that created this large surface scar. |
So what’s next for Dawn? The explorer will continue work at Vesta, swooping to within 130 miles of the asteroid’s surface, until August 26. Then it’s off to Ceres, with arrival planned for February, 2015.
For more on Dawn and the incredible scientific discoveries being revealed by this vehicle, please visit NASA’s mission page at: http://www.nasa.gov/dawn
