NASA Returns Asteroid Probe to Launch Pad
NASA's Dawn spacecraft arrives at Pad-17B of the Cape Canaveral Air Force Station in the early morning on Sept. 11, 2007. Next stop - the Asteroid Belt.
Credit: NASA/Jack Pfaller

A beleaguered NASA probe bound for the solar system's two largest space rocks returned to its Florida launch pad Tuesday after two months of delay.

Engineers hoisted the space agency's Dawn asteroid probe atop its Delta 2 rocket at the Cape Canaveral Air Force Station following a series of launch delays and scrubs earlier this summer.

"From here, the only way to go is up," said Dawn project manager Keyur Patel, of NASA's Jet Propulsion Laboratory in Pasadena, California, in a statement. "We are looking forward to putting some space between Dawn and Mother Earth and making some space history."

Dawn is slated to begin its planned eight-year mission to the asteroids Vesta and Ceres with a 7:25 a.m. EDT (1125 GMT) launch on Sept. 26.

Vesta is a bright, dense asteroid, while the spherical Ceres is large enough to be considered a dwarf planet. Dawn researchers hope that by studying the two space rocks, they will better understand how planets formed in the early solar system.

Earlier attempts to launch Dawn in July were plagued by bad weather, booster glitches and difficulties in arranging air and ship-based tracking systems for the planned liftoff.

Mission managers opted to postpone Dawn's mission until September, after the launch of NASA's Phoenix Mars Lander. The delay is expected to add about $25 million to Dawn's $449 million mission cost, NASA has said.

NASA also canceled Dawn's mission outright in March 2006, but reinstated the asteroid expedition a few weeks later after reevaluating budget and technical hurdles.

Dawn is slated to rendezvous and orbit Vesta in 2011 before heading off for a February 2015 appointment with Ceres. Both asteroids sit in the Asteroid Belt that runs between the orbits of Mars and Jupiter.

NASA must launch Dawn by late October, after which its space rock targets will begin moving away from one another in their respective orbits. After Dawn's 2007 launch window, Ceres and Vesta won't be near enough to one another for about 15 years, mission managers have said.