The asteroid Lutetia at closest approach as seen by Europe's Rosetta spacecraft in July 2010.
Credit: ESA Full Story
The first close-up photos of the battered asteroid Lutetia taken by a European spacecraft have amazed scientists with views of a possible otherworldly landslide and a deep depression gouged across the landscape that hints at the space rock's ancient, violent past.
The new photos of Lutetia, beamed back from the European Space Agency's (ESA) Rosetta space probe during a Saturday flyby, show what scientists said is a primitive asteroid survivor from the tumultuous birth of the solar system.
"I think this is a very old object," said Holger Sierks, principal investigator for Rosetta's main scientific imaging system, OSIRIS, in a statement on the night of the flyby. "Tonight we have seen a remnant of the solar system's creation."
Close views of Lutetia show that the space rock is covered in craters from many impacts during its 4.5 billion years of existence.
As Rosetta drew close, a giant bowl-shaped depression stretching across much of the body of Lutetia rotated into view. What appeared to be an asteroid landslide was also spotted in the spacecraft's photos.
In another striking photo, the ringed planet Saturn can be seen in the distance beyond Lutetia as the asteroid hovers in the foreground. [ Photo of asteroid Lutetia and Saturn.]
Rosetta's flyby confirmed that Lutetia is an elongated body, with its longest side spanning approximately 81 miles (130 km), ESA officials said.
The Rosetta spacecraft is actually headed to visit the comet 67P/Churyumov-Gerasimenko in 2014. The Lutetia flyby ? as well as an earlier visit to the asteroid Steins in 2008 ? was a pit stop on the way to the probe's ultimate comet destination.
"It has been a great day for exploration, a great day for European science," said David Southwood, ESA Director of Science and Robotic Exploration, in a statement. "The clockwork precision is a great tribute to the scientists and engineers in our Member States in our industry and, not least, in ESA itself. Roll on 2014 and our comet rendezvous."
The asteroid Lutetia remained a mystery for many years until Rosetta's Saturday flyby, largely because previous observations from ground-based telescopes found some confusing asteroid characteristics.
Some measurements placed the asteroid in the 'C-type' category left over from the formation of the solar system, which means it contains primitive compounds of carbon. Yet other studies suggested Lutetia was an 'M-type', which would mean that there are metals on its surface. These have been associated with iron meteorites, are usually reddish and thought to be fragments of the cores of much larger objects.
The new pictures of Lutetia came from Rosetta's OSIRIS instrument, which combines a wide angle and a narrow angle camera. At closest approach, details down to a scale of almost 200 feet (60 m) can be seen over the entire surface of the asteroid.
The new images, combined with compositional data, will help astronomers determine how Lutetia stacks up with other solar system asteroids, researchers said.
Rosetta turned its full suite of instruments on Lutetia during the weekend encounter, including remote sensing and in-situ measurements.
Mission managers even switched on some of the instruments on Rosetta's Philae lander, which will land on the probe's target comet, to take more observations. Together, Rosetta and its lander scoured for evidence of any highly tenuous atmosphere or magnetic effects on Lutetia, and recorded the space rock's surface composition and density.
Rosetta and its Philae lander also attempted to catch any dust grains that may have been floating in space near the asteroid for additional on-board analysis, ESA officials said. The data and results from these instruments are expected to come at a later time.
A speedy visit
Rosetta zoomed past the asteroid Lutetia on July 10, at a relative speed of 32,400 mph (52,142 kph). The closest approach took place at about 1610 GMT (12:10 p.m. EDT), at a distance of about 1,900 miles (3,162 km).?
Still, the cameras and other instruments onboard Rosetta had been working for hours, and in some cases days, beforehand. ESA released preliminary images as the spacecraft neared Lutetia, showing the asteroid growing larger on approach.
Rosetta will now continue on its path to the spacecraft's primary target, a rendezvous with the comet 67P/Churyumov-Gerasimenko in 2014. It will then accompany the comet for months, from near the orbit of Jupiter down to its closest approach to the sun.
In November 2014, Rosetta is expected to release the Philae lander to touch down on the comet's nucleus.