NASA's robotic probe named Dawn has beamed back close-up images of asteroid Vesta, the second most massive object in the Asteroid Belt. From dusty landslides to towering mountains, the new images reveal unprecedented details of the roughly 328-mile-wide, 4.6-billion-year-old rock. Planetary scientists have waited nearly four years for Dawn to reach its first target after launching Sept. 27, 2007. The probe is slated to journey to the potentially muddy and icy protoplanet Ceres in July 2012. Dawn slipped into orbit around Vesta on July 16, 2011 by spitting a steady stream of ions from its engine. Although the probe has returned other images of Vesta since arriving at the space rock, the latest batch of photos, taken from an orbit of 1,700 miles above the asteroid’s surface, are the most detailed yet. We showcase the best shots provided by NASA and its partners in this gallery. Above: Crater Fields (3-D) Counting craters on Vesta’s surface can help planetary scientists figure out their relative ages — and donning 3-D glasses helps them count. Image: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA [high-resolution version]

New Discoveries on Asteroid Vesta Planetary scientist Carol Raymond of NASA’s Jet Propulsion Laboratory, one of the Dawn mission’s leaders, sums up the findings from the spacecraft’s latest batch of imagery. Video: NASA Jet Propulsion Laboratory California Institute of Technology [high-resolution version]

Anatomy of an Impact Crater To better view the details of large impact craters and their tossed-out detritus, mission managers apply false color. Reddish hues in this image reveal material that either came from the object which slammed into Vesta, or debris ejected from Vesta’s interior. Image: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA [high-resolution version]

Claudia, the Prime Meridian Crater This 1,640-foot-wide crater will help Dawn’s staff precisely measure Vesta’s orientation, rotation axis and equator. Planetary scientists named the object Claudia after a famous Roman woman who lived during 200 B.C. They plan to name bigger craters after priestesses of the Vesta, the Roman goddess of the home. Image: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA [

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Polar Cliffs Although Vesta has a surface area roughly the size of the state of California, its cliffs — some several miles high — dwarf those on Earth. Scientists guiding Dawn’s mission have already spied strange landslide-like features near the cliffs, but how the steep slopes formed is still a mystery. Image: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA [high-resolution version available]

Vesta’s South Pole Impact craters ranging in size from 10- to 30-miles-wide dot this image of Vesta’s south pole. Planetary scientists created the shot by stitching dozens of images together. Image: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA [high-resolution version]

Circular South Pole Strange circular patterns at Vesta’s south pole could have arisen from a colossal impact or unknown dynamics inside of the giant asteroid. Image: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA [high-resolution version available]

First Global Map of Vesta By orbiting around Vesta’s surface from 1,700 miles up, Dawn has created this first full map of the asteroid’s pockmarked surface. Vesta’s strange grooves are clearly visible in this image, with the north pole (top) and south pole (bottom) stretched to accommodate a square space. Image: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA [high-resolution version available]

Groovy Terrain (3-D) Ridges, grooves, impact craters and other features in this stereoscopic view of Vesta can pop out in 3-D with the help of red/blue glasses. Image: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA [high-resolution version available]

Big Mountain (3-D) Put on a pair of red/blue 3-D glasses and watch this 9-mile-high mountain (center, right) tower over Vesta’s ruined landscape. Fissures created by tectonic tension also reveal themselves in this stereoscopic composite. Image: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA [high-resolution version available]

Rolling Mountain Range Another view of the 9-mile-high mountain discovered on Vesta’s south pole. The base of the rock pile extends roughly 125 mile in diameter. Image: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA [

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