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Rosetta probe makes asteroid pass

6 September 08 20:12 GMT

The Rosetta space probe has made a close pass of asteroid Steins.

The European Space Agency mission flew past the 5km-wide rock at a distance of about 800km, taking pictures and recording other scientific data.

The information was sent back to Earth for processing late on Friday and released to the public on Saturday.

The asteroid pass is a bonus for Rosetta. Its prime goal is to catch and orbit Comet 67P/Churyumov-Gerasimenko out near Jupiter in 2014.

Friday's pass occurred about 360 million km from Earth, in between the orbits of Mars and Jupiter, in the asteroid belt.

The pictures revealed a large crater about two kilometres across on the top of (2867) Steins - to give the rock its full designation.

Seven smaller craters could be seen running down one side of the rock in a line.

"Steins looks like a diamond in the sky," said Rosetta scientists Uwe Keller at Saturday's press conference. "We observed a new jewel in the Solar System."

The mission will make another asteroid rendezvous as it works its way out to Jupiter.

The probe will visit the (21) Lutetia space rock on 10 June 2010, but from the larger distance of 3,000 km.

Only a few asteroids have so far been observed up close. They have been shown to be very different in shape and size - ranging from a few km to over 100km across - and in their composition.

The rocks are often referred to as "space rubble" because they represent the leftovers that were never incorporated into planets when the Solar System formed 4.6 billion years ago.

As with comets, they may contain very primitive materials that have not undergone the constant recycling experienced by, for example, Earth rocks.

Rosetta data should therefore help researchers understand better how our local space environment has evolved over time.

The £600m Rosetta mission was blasted into space on 2 March, 2004.

Once in orbit around the 4km-wide Churyumov-Gerasimenko, the craft will despatch a small lander called Philae to the surface to study the object's chemistry.

The mission will then follow the comet as it moves in towards the Sun, monitoring the changes that take place on the icy body.

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