A US spacecraft is on track to rendezvous with a huge asteroid in a matter of weeks, NASA said, shedding new light on the history of cosmos.

The Dawn spacecraft will go into orbit around the asteroid Vesta July 16 and begin gathering data in early August, a NASA release said Thursday.

The spacecraft is right on target, said Robert Mase, Dawn project manager at NASA's Jet Propulsion Laboratory in Pasadena, Calif. We look forward to exploring this unknown world during Dawn's one-year stay in Vesta's orbit.

After traveling for nearly four years, 1.7 billion miles and two laps around the Sun, said Mase.

Dawn has been taking pictures of Vesta as it approaches, which are twice as sharp as anythign seen from the Hubble space telescope.

The spacecraft will spend a year orbiting Vesta and studying its atmosphere, magnetic fields, and the make up of the comet.

The mission is unusual because it won't stop after this assessment is made.

Instead, the Dawn will fire its engines again and climb away toward the dwarf planet Ceres, the largest object in the asteroid belt. It is expected to get there and drop into orbit in early 2015.