Friday, December 23, 2011

Closer and Closer to the Vesta Surface

NASA's Dawn spacecraft has spiraled closer and closer to the surface of the giant asteroid Vesta. These images were obtained by Dawn's framing camera in the three phases of its campaign since arriving at Vesta in mid-2011.

The two images on the left represent an identical area, first observed during Dawn's survey orbit (far left image). That orbit aimed to obtain a global characterization of the asteroid. The picture in the center is from Dawn's high-altitude mapping orbit (HAMO) when the surface was systematically imaged during September and October 2011 from an altitude of about 430 miles (700 kilometers) with about 230 feet (70 meters-per-pixel) resolution for global high-resolution stereo image data that were used to develop a global shape model and topographic maps.

Since December 12, 2011, the orbiter has been circling Vesta in a slightly elliptical orbit known as low-altitude mapping orbit (LAMO) at an average 130 miles (210 kilometers) above the asteroid's surface. The image on the right was obtained on December 13 from an altitude of 124 miles (199 kilometers) to the surface and has a resolution of 75 feet (23 meters) per pixel. It covers an area about 12 miles by 12 miles (19 kilometers by 19 kilometers).

The low altitude image has a resolution more than three times better than the resolution from the HAMO phase. There is a lot more detail in the image, like small impact craters or slumping at the steep-flanked mountain in the image center that can be identified in the two images to the left. The center of the LAMO image is at about 45.5 degrees south latitude and 325.1 degrees east longitude.

Photo credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

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