NASA's asteroid probe Dawn entered orbit around Vesta at roughly 1:00 a.m. EDT on July 16th. Since then, mission scientists at the Jet Propulsion Lab (JPL) in California have been getting ever closer peeks at the asteroid.
This week alone, the team released two sets of images (on Monday and Thursday) of the 330-mile-wide, oddly-shaped asteroid that orbits in the main asteroid belt between Mars and Jupiter. Taken on July 17th and 18th, when the craft was 9,500 miles and 6,500 miles from Vesta, respectively, these images reveal a bumpy terrain peppered with craters.
A large rocky protuberance in the south polar region of the asteroid had begun to come into focus in images taken on July 9th, a week before Vesta captured Dawn. In this week's images this mountain appears to loom large beside impact craters and steep bluffs on the asteroid.
Scientists are not sure what to call this structure on Vesta's surface yet. In an email to Sky & Telescope planetary scientist, Jim Bell (Arizona State University) said that it is best to use descriptive terms to define features of unknown origin. His personal description would be "a roughly-circular, dome-like hill near the center of what appears to be a large circular, possibly crater-like depression."
The mission's engineers, headed by Marc Rayman, the author of the Dawn Journals, are using these images to steer the craft downward into its science orbit (1,700 miles from the surface), and to calibrate the camera and spectrometer for subsequent imaging.
The craft's wide-angle framing camera, which is currently being used for navigation, will later allow scientists to map the asteroid, Rayman says.
A gallery of Dawn's images allows enthusiasts to follow the mission closely. In upcoming days, Dawn will return more remarkable vistas of Vesta, making the ride more enjoyable.