NASA releases first closeups of asteroid (photos)

After traveling 1.7 billion miles over four years, NASA's Dawn spacecraft has begun sending images of the asteroid Vesta back to Earth. NASA will begin the investigation of Vesta in more detail after it maneuvers the spacecraft into an orbit about 1,700 miles from the asteroid.

Here is the first full-frame photo of Vesta taken on July 24 from a distance of about 3,200 miles. Vesta is abou 114 million miles from Earth.

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

NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

This view of the dark side of Vesta was taken from a distance of about 3,200 miles.

NASA describes the instruments brought aboard Dawn:

"In addition to the framing camera, Dawn's instruments include the gamma ray and neutron detector and the visible and infrared mapping spectrometer. The gamma ray and neutron detector uses 21 sensors with a very wide field of view to measure the energy of subatomic particles emitted by the elements in the upper yard (meter) of the asteroid's surface. The visible and infrared mapping spectrometer will measure the surface mineralogy of both Vesta and Dawn's next target, the dwarf planet Ceres."

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

Here's an image of the south pole of Vesta. This asteroid could be the origin of many meteors that have hit Earth.

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

This set of three craters is in the northern hemisphere of Vesta. They've been nicknamed "Snowman."

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

One of Dawn's first images of Vesta on its approach shows the large bump on its surface.

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

Vesta's equatorial region is marked by grooves.

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

The ion propulsion system goes through a test on Earth. Dawn has three 30-centimeter-diameter (12-inch) ion thrust units. It produces an electrical charge to accelerate ions from xenon fuel that will be 10 times faster than chemical fuel.

The spacecraft uses only 10 ounces of fuel per day and would accelerate on an Earth highway from 0 to 60 miles per hour in 4 days. But without gravity in space, its got speed to burn.