NASA's Dawn spacecraft is preparing to enter an orbit around the asteroid Vesta for the first mission to study a large main-belt asteroid.
Dawn will study Vesta in the main asteroid belt lying between the orbits of Mars and Jupiter for one year, providing data to help scientists understand the earliest chapter of our solar system's history, a NASA release said Thursday.
Engineers expect the spacecraft to be captured into Vesta's orbit at approximately 1 a.m. EDT Saturday.
The asteroid and the orbiting spacecraft will be approximately 117 million miles from Earth, scientists said.
"It has taken nearly four years to get to this point," said Robert Mase, Dawn project manager at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "Our latest tests and check-outs show that Dawn is right on target and performing normally."
After its one-year mission at Vesta, the spacecraft, launched in September 2007, will depart for its second destination, the dwarf planet Ceres, in July 2012.
Dawn will be the first space probe to orbit two solar system destinations beyond Earth, NASA said.