Rosetta’s hot date with Lutetia

Space scientists are celebrating after a European probe sent home spectacular photos of the biggest asteroid ever visited. Astronomers at mission control cheered as dramatic pictures of the 83-mile long rock called Lutetia arrived from their unmanned Rosetta explorer.

Close-up of Lutetia. Image credit: ESA

They showed an irregular world looking, as we have come to expect, more like a potato than a planet and heavily scarred by craters from meteor impacts.

There are also strange grooves etched across its surface plus a giant bowl-shaped depression which shows signs of a landslide. They seemed reminiscent of features on Mars’ larger moon Phobos, which is thought to be a captured asteroid.

One photo taken as Rosetta began its approach delighted astronomers by showing the recognisable shape of the ringed planet Saturn in the background.

Lutetia is thought to be basically unchanged otherwise since the birth of the solar system 4.5 billion years ago, unlike Earth which has seen constant churning of its rocks. This means that the asteroid will help scientists understand more about how the Sun’s family of planets formed.

Holger Sierks of the Max Planck Institute for Solar System Research at Lindau, Germany, principal investigator for one of Rosetta’s imaging cameras called OSIRIS, said: “I think this is a very old object. Tonight we have seen a remnant of the solar system’s creation.”

A crescent view as Rosetta departs.
Image credit: ESA

UK scientists are backing the £835 million Rosetta mission. The probe, launched in 2004, passed within 2,000 miles of Lutetia, travelling at 34,000mph. Its camera and other instruments spent more than two hours taking details photos and measurements.

First pictures were delivered via a giant radio telescope dish in Spain to the European Space Agency’s mission control at Darmstadt, Germany. Professor David Southwood, ESA’s Director of Science and Robotic Exploration, said: “It has been a great day for exploration, a great day for European science.”

Rosetta has already flown past another asteroid called Steins in September 2008. The spaceprobe has made a number of swings past the Earth and Mars in a kind of interplanetary snooker to gain speed.

Its mission, which is also backed by NASA, is designed finally to land a smaller probe on a comet called Comet Churyumov-Gerasimenko in 2014.

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