NASA's Dawn spacecraft has successfully maneuvered into its closest orbit around the giant asteroid Vesta.
The spacecraft is currently circling Vesta at an altitude averaging approximately 130 miles (210 kilometers), as it kicks off the next phase of its mission known as low altitude mapping orbit.
"Dawn has performed some complicated and beautiful choreography in order to reach this lowest orbit," explained Marc Rayman, Dawn chief engineer and mission manager based at NASA's Jet Propulsion Laboratory, Pasadena, Calif.
"We are [now] in an excellent position to learn much more about the secrets of Vesta's surface and interior."
Launched in 2007, Dawn has been in orbit around Vesta, the second most massive object in the asteroid belt between Mars and Jupiter, since July 15. The team plans to acquire data in the low orbit for at least 10 weeks.
Dawn's framing camera and visible and infrared mapping spectrometer instruments will image portions of the surface at greater resolution than obtained at higher altitudes. However, the primary goal of the low orbit mission is to collect data for the gamma ray and neutron detector (GRaND), as well as for a gravity experiment.
Indeed, GRaND will be searching for the by-products of cosmic rays reflected off Vesta to reveal the identities of various atoms in the surface of the asteroid. Close proximity to Vesta also enables ultrasensitive measurements of its gravitational field, providing scientists with new data about the way masses are arranged in the giant asteroid's interior.
"Dawn's visit to Vesta has been eye-opening so far, showing us troughs and peaks that telescopes only hinted at," said Christopher Russell, Dawn's principal investigator, based at UCLA.
"It whets the appetite for a day when human explorers can see the wonders of asteroids for themselves."
After Dawn completes its low altitude mapping, the spacecraft will spiral out and conduct another science campaign at the high altitude mapping orbit altitude (420 miles, or 680 kilometers), when the sun will have risen higher in the northern regions.
Dawn is slated to leave Vesta in July 2012 and arrive at its second destination, the dwarf planet Ceres, in February 2015.