Mission to asteroids is on its way

An unmanned spaceprobe blasted off today on a mission into the heart of the asteroid belt – using technology straight out of Star Wars.

Nasa’s Dawn mission will fly into a band of thousands of rocky worlds that lie between the orbits of Mars and Jupiter. It will seek to discover more about the biggest two of these mini-planets, Ceres and Vesta.

The probe launched, rather fittingly, shortly after dawn local time on September 27, from pad 17-B at Cape Canaveral, Florida. Aboard the ship is a chip carrying the names of more than 360,000 space fans from around the world who submitted their details to Nasa.

Dawn will fly on a four-billion mile journey, propelled by three ion engines like those that drive the fighter ships in Star Wars. It will take four years to reach its first target, Vesta, spending six months there, then move on to Ceres, the largest of the asteroids, which was promoted to the status of dwarf planet last year when Pluto got downsized. Arrival at Ceres is due in February 2015.

The thrusters, which produce beams of electrically charged atoms, have to fire for months at a time to build speed and steer the spacecraft. Over eight years, they will fire for a total 50,000 hours – a record for a spacecraft.

Vesta and Ceres are different in their make-up. Vesta, which can just be glimpsed with the naked eye, is 350 miles across and thought to be mainly a rocky world like Earth, while 600-mile wide Ceres is an icy body like the outer planets. Both will provide important clues about the formation of the solar system.

Principal Investigator Christopher Russell, of the University of California, Los Angeles, said: “These two very diverse bodies reside in essentially the same neighbourhood. It is one of the mysteries Dawn hopes to solve.”

Colleague David Lindstrom said: “Understanding conditions that lead to the formation of planets is a goal of Nasa’s mission of exploration. The science returned from Vesta and Ceres could unlock many of the mysteries of the formation of the rocky planets including Earth.”

Dawn is lucky to be flying. The £255 million mission was cancelled by Nasa to save money but reprieved just weeks later, last year, after protests from planetary scientists.

The Nasa photo shows final checks being carried out on the Dawn spacecraft.

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