罗塞塔探测器经过小行星卢滕西亚

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罗塞塔探测器经过小行星卢滕西亚
The encounter took Rosetta to 3,162km from Lutetia at closest approach. The probe flew past at 15km/s
Europe's Rosetta space probe has flown past the Asteroid Lutetia, returning a stream of scientific data for analysis.
The huge rock - about 120km in its longest dimension - is the biggest asteroid yet visited by a satellite.
Pictures showed Lutetia to be quite irregular in shape, its surface marked by a number of wide impact craters and even some intriguing grooves.
Rosetta's encounter with the asteroid occurred some 454 million km from Earth, beyond the orbit of Mars.
Scientists hope the data will help them determine Lutetia's true nature.
"The pictures are majestic; they take my breath away," Professor David Southwood, the European Space Agency's director of science, told BBC News.
"It is an historic day, Europe once again proving it can do major steps in Solar System exploration. Everything worked like clockwork. It really was picture perfect," he said.
Earth-based telescopes have had great difficulty in classifying Lutetia.
Some observations have suggested it is a very primitive body, little changed since its formation (a so-called C-type asteroid).
Other measurements, though, have also spied what appear to be metals in its surface, indicating the rock might have undergone a greater degree of evolution (M-type asteroid).
Lutetia might even be the fragmented remains of a much larger asteroid smashed apart in a great collision.
Rosetta will attempt to resolve these issues once and for all.
Nearly all of the Rosetta mission's instruments were switched on for a period of several hours around closest approach (1544 GMT; 1644 BST; 1744 CEST).
Multi-wavelength cameras and spectrometers, magnetic field and plasma experiments, dust instruments, a radio science experiment - all were tasked with gathering as much information as possible as the spacecraft whizzed by at the relative speed of 15km/s and a minimum distance of 3,162km.
Scientists say it will be some days before they can start to make some definitive statements about Lutetia's origins.
THE ROSETTA PROBE MAKES ITS CLOSE PASS OF ASTEROID LUTETIA
Asteroids are the ancient remnants left over from the formation of the Solar System Most are made of rock, but some are also composed of metal, mostly nickel and iron Their sizes range from small boulders to objects that are hundreds of km in diameter Most asteroids reside in the vast region of space that exists between Mars and Jupiter |
Before this flyby, the largest asteroid encountered by a spacecraft was Mathilde, which is a little over 50km wide.
Mathilde was visited by the US space agency's (Nasa) Near-Shoemaker probe in 1997.
Rosetta itself has already made one close asteroid flyby, of the Steins rock in 2008.
With this latest pass complete, Rosetta is now heading out to its meeting with the Comet Churyumov-Gerasimenko, set for the May of 2014.
The probe will go into orbit around the 4km-wide ball of ice and dust and even place a small lander called Philae on its surface.
Asteroids are the object of keen interest currently. The Japanese Hayabusa mission has recently returned from the Itokawa space rock, and next year the US Dawn mission will go into orbit around Asteroid Vesta.
The American President Barack Obama says Nasa should also have
the goal of trying to send astronauts to an asteroid sometime in
the 2020s.
The detail at closest approach is about 60m per pixel. These images
show grooves on the surface