ESA's Rosetta headed for 'blind date' with asteroid Lutetia

Washington, June 16 (ANI): The European Space Agency's Rosetta comet chaser is heading towards asteroid Lutetia for what is being touted as a 'blind date'.

Rosetta has not had a glimpse of Lutetia yet and the two will meet on July 10 as it flies within 3,200 km of the space rock.

Rosetta started taking navigational sightings of Lutetia at the end of May so that ground controllers can determine any course corrections required to achieve their intended flyby distance.

The close pass will allow around 2 hours of good imaging.

The spacecraft will instantly begin beaming the data back to Earth and the first pictures will be released later that evening.

Orbiting in the main belt of asteroids between Mars and Jupiter, Lutetia appears as a single point of light to ground telescopes.

The continuous variation in its brightness makes it clear that Lutetia is rotating and has an uneven surface.

These observations allow astronomers to estimate its shape and size, but their determinations all differ.

Initially it was thought that Lutetia is around 95 km in diameter but only mildly elliptical.

A more recent estimate suggests 134 km, with a pronounced elongation. Rosetta will tell us for certain and will also investigate the composition of the asteroid, wherein lies another mystery.

By any measure, Lutetia is quite large.

Planetary scientists believe that it is a primitive asteroid left on the shelf for billions of years because no planet consumed it as the Solar System formed.

Indeed, most measurements appear to back this picture, making the asteroid out to be a 'C-type', which contains primitive compounds of arbon.

However, some measurements suggest that Lutetia is an 'M-type', which could mean there are metals in its surface.

"If Lutetia is a metallic asteroid then we have found a real winner," said Rita Schulz, ESA Rosetta Project Scientist.

That is because although metallic asteroids do exist, they are thought to be fragments of the metallic core of larger asteroids that have since been shattered into pieces.

If Lutetia is made of metal or even contains large amounts of metal, the traditional asteroid classification scheme will need rethinking, Dr. Schulz said.

She said: "C-class asteroids should not have metals on their surfaces."

For 36 hours around the moment of closest approach, Rosetta will be in almost continuous contact with the ground. The only breaks will come as Earth rotates and engineers have to switch from one tracking station to another.

Good contact is essential because the uncertainties in the asteroid's position and shape may demand last minute fine-tuning to keep it centred in Rosetta's instruments during the flyby.

"The skeleton of the operation is in place, and we have the ability to update our plans at any time," says Andrea Accomazzo, ESA Rosetta Spacecraft Operations Manager. (ANI)