Dawn probe sends back images of asteroid

Posted by Emma Woollacott

NASA's Dawn probe is beginning the first of four science orbits, and has sent back its first close-up images.

At an altitude of nearly 1,700 miles, Dawn will provide in-depth analysis of the asteroid. Because the giant asteroid turns on its axis once every five hours and 20 minutes, the images will cover the entire surface.

"Now that we are in orbit around one of the last unexplored worlds in the inner solar system, we can see that it's a unique and fascinating place," says Marc Rayman, Dawn's chief engineer and mission manager.

Along with its framing camera, Dawn's instruments include a gamma ray and neutron detector and a visible and infrared mapping spectrometer. They'll be used to measure the energy of subatomic particles emitted by the elements in the upper yardof the asteroid's surface. The visible and infrared mapping spectrometer, as well as the surface mineralogy.

"We have been calling Vesta the smallest terrestrial planet," says Chris Russell, Dawn's principal investigator.

"The latest imagery provides much justification for our expectations. They show that a variety of processes were once at work on the surface of Vesta and provide extensive evidence for Vesta's planetary aspirations."

Dawn will also make another set of scientific measurements at Vesta and Ceres using the spacecraft's radio transmitter in tandem with sensitive antennas on Earth. Subtle variations in the objects' gravity fields should provide clues about the bodies' interior structure.

Vesta is the brightest object in the asteroid belt as seen from Earth and is thought to be the source of a large number of meteorites that fall to Earth.