July 11, 2010 11:49am
THE European spacecraft Rosetta performed a fly-by of a massive asteroid, taking images that could one day help Earth defend itself from destruction.
Racing through the asteroid belt between Mars and Jupiter at 47,800k/ph, the one billion euro ($1.45 billion) probe flew within 3200km of the huge potato-shaped rock, Lutetia.
"The fly-by has been a spectacular success with Rosetta performing faultlessly,'' ESA said in a statement.
"Just 24 hours ago, Lutetia was a distant stranger. Now, thanks to Rosetta, it has become a close friend,'' the agency added.
Holger Sierks of Germany's Max Planck Institute, who is in charge of the spacecraft's Osiris (Optical, Spectroscopic and Infrared Remote Imaging System) camera said the more than 400 "phantastic images'' showed many craters and details.
"Rosetta opened up a new world which will keep scientists busy for years,'' he added.
"We have completed the fly-by phase,'' Rosetta's director of operations Andrea Accomazzo said earlier on the ESA's website from the European Space Operations Centre in Darmstadt, Germany.
The aim of the fly-by of the asteroid, measuring 134km in diameter, is to measure Lutetia's mass and then calculate its density, knowledge which could one day be a lifesaver, according to ESA scientists.
If a rogue asteroid enters on a collision course with Earth, knowing its density will help the planet's defenders to determine whether they should try to deflect the rock or, instead, blow it up.
As Rosetta is around half a million kilometres from Earth, the probe's signal and images took 25 minutes to be received.
Most measurements suggest Lutetia is a "C'' type of asteroid, meaning that it contains primitive compounds of carbon. But others indicate it could be an "M'' type, meaning that it holds metals.
New data proving this could rewrite the theory about asteroid classification.
Metallic asteroids are far smaller than Lutetia: they are deemed to be fragments of far larger rocks that, in the bump and grind of the asteroid belt, were smashed apart.
The fly-by comes halfway through the extraordinary voyage of Rosetta, launched in 2004 on a 12-year, 7.1 billion kilometre mission.
One of the biggest gambles in the history of space exploration, the unmanned explorer is designed to meet up in 2014 with Comet 67/P Churyumov-Gerasimenko 675 million kilometres from home.
The goal is to unlock the secrets of these lonely wanderers of the cosmos, whose origins date back to the dawn of the Solar System, some 4.5 billion years ago, before planets existed.
To get to its distant meeting point, Rosetta has had to play planetary billiards for five years, using four "gravitational assists'' from Earth and Mars as slingshots to build up speed.
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