Hubble Images of Asteroid Help NASA Refine Dawn Science Plans

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NASA’s Hubble Space Telescope captured images of the asteroid Vesta that will help scientists refine plans for the Dawn spacecraft’s July 2011 rendezvous with the near-Earth object, the agency announced Oct. 8.

Images obtained by Hubble’s Wide Field Camera 3 in February show that Vesta’s pole orientation, or tilt, is approximately four degrees greater than scientists previously thought.

As a result, the change of seasons between Vesta’s southern and northern hemispheres may occur about a month later than previously expected while Dawn is orbiting the asteroid. The new information gives scientists a better idea of the sunlight patterns Dawn will encounter, helping them plan the spacecraft’s imaging and mapping activities, NASA said.

“The new results give us food for thought as we make our way toward Vesta,” Dawn’s principal investigator, Christopher Russell of the University of California, Los Angeles, said in a statement. “Because our goal is to take pictures of the entire surface and measure the elevation of features over most of the surface to an accuracy of about [10 meters], or the height of a three-story building, we need to pay close attention to the solar illumination. It looks as if Vesta is going to have a late northern spring next year, or at least later than we planned.”

Dawn launched in September 2007 atop a Delta 2 rocket. The 1,250-kilogram spacecraft was built by Dulles, Va.-based Orbital Sciences Corp.