BERLIN — The European Space Agency has taken the closest look yet at asteroid Lutetia in an extraordinary quest some 280 million miles in outer space between Mars and Jupiter.
The comet-chaser Rosetta transmitted its first pictures from the largest asteroid ever visited by a spacecraft Saturday night after it flew by Lutetia as close as 1,900 miles, ESA said in Darmstadt, Germany.
"These are fantastic and exciting pictures," space agency scientist Rita Schulz said in a webcast presentation. She said it would take several weeks before all 400 pictures and all data from the high-precision instruments aboard Rosetta would come through to Earth.
"I am a very happy man," said ESA manager David Southwood. "It is a great day for European Science and for world science."
Though Lutetia was discovered some 150 years ago, for a long time it was little more than a point of light to those on Earth. Only recent high-resolution ground-based imaging has given a vague view of the asteroid, the agency said.
"At the moment we know very little about it," Schulz said.
Lutetia is believed to be 83.3 miles in diameter with a "pronounced elongation," but scientists have been puzzled as to what type of asteroid it is — a "primitive" one containing carbon compounds or a metallic asteroid.
"We are now going to get the details of this asteroid, which is very important," Schulz said. "There will be a lot of science coming from that mission."
Scientists hope to find in the information and images gathered by Rosetta clues to the history of comets and asteroids and of the solar system, Schulz said.
For Rosetta, examining Lutetia and other asteroids is only a side event on its long journey to comet 67P/Churyumov-Gerasimenko — the mission's destination, said project manager Gerhard Schwehm.
Rosetta was launched in 2004.
Rosetta is set to meet up with the comet in 2014 and then escort it around the sun. This fly-by presents astronomers with a unique opportunity before the main event, said Joseph Hora, an astronomer at the Harvard-Smithsonian Center for Astrophysics who is not involved in the mission.
Though the wait is long, scientists are certain it is going to be worthwhile, Schwehm said.
"We want to study the material out of which the planets formed," he said. This is possible only close up, he said.
Pulling off such a maneuver is "really eye-of-the-needle amazing, because you're trying to arrive at a location in space and time at the same time this asteroid is zipping by," Hora said.