Grooves found on Lutetia, an asteroid encountered by ESAs Rosetta spacecraft, point to the existence of a large impact crater on the unseen side of the rocky world. Rosetta flew past Lutetia at a distance of 3168 km in July 2010, en route to its 2014 rendezvous with its target comet. The spacecraft took images of the 100 km-wide asteroid for about two hours during the flyby, revealing numerous impact craters and hundreds of grooves all over the surface. Read more
The Moon will occult the magnitude 9.7 asteroid (21) Lutetia at ~06:00 UT, 15th July, 2012. The event is visible from the UK, Scandinavia and northern Russia.
The long and tumultuous history of asteroid Lutetia was revealed by ESA's Rosetta spacecraft as it raced past this large, ancient asteroid. This spectacular movie shows a sequence of images snapped by Rosetta as it flew past the main-belt asteroid on 10 July 2010. Read more
Title: The Cratering History of Asteroid (21) Lutetia Authors: S. Marchi (1), M. Massironi (2), J.-B. Vincent (3), A. Morbidelli (1), S. Mottola (4), F. Marzari (2), M. Kueppers (5), S. Besse (6), N. Thomas (7), C. Barbieri (2), G. Naletto (2), H. Sierks (3) ((1) OCA, (2) University of Padova, (3) MPS, (4) DLR, (5) ESAC, (6) LAM, (7) University of Bern)
The European Space Agency's Rosetta spacecraft passed by the main belt asteroid (21) Lutetia the 10th July 2010. With its ~100km size, Lutetia is one of the largest asteroids ever imaged by a spacecraft. During the flyby, the on-board OSIRIS imaging system acquired spectacular images of Lutetia's northern hemisphere revealing a complex surface scarred by numerous impact craters, reaching the maximum dimension of about 55km. In this paper, we assess the cratering history of the asteroid. For this purpose, we apply current models describing the formation and evolution of main belt asteroids, that provide the rate and velocity distributions of impactors. These models, coupled with appropriate crater scaling laws, allow us to interpret the observed crater size-frequency distribution (SFD) and constrain the cratering history. Thanks to this approach, we derive the crater retention age of several regions on Lutetia, namely the time lapsed since their formation or global surface reset. We also investigate the influence of various factors -like Lutetia's bulk structure and crater obliteration- on the observed crater SFDs and the estimated surface ages. From our analysis, it emerges that Lutetia underwent a complex collisional evolution, involving major local resurfacing events till recent times. The difference in crater density between the youngest and oldest recognized units implies a difference in age of more than a factor of 10. The youngest unit (Beatica) has an estimated age of tens to hundreds of Myr, while the oldest one (Achaia) formed during a period when the bombardment of asteroids was more intense than the current one, presumably around 3.6Gyr ago or older.
Lutetia: a Rare Survivor from the Birth of the Earth
New observations indicate that the asteroid Lutetia is a leftover fragment of the same original material that formed the Earth, Venus and Mercury. Astronomers have combined data from ESA's Rosetta spacecraft, ESO's New Technology Telescope, and NASA telescopes. They found that the properties of the asteroid closely match those of a rare kind of meteorites found on Earth and thought to have formed in the inner parts of the Solar System. Lutetia must, at some point, have moved out to its current location in the main asteroid belt between Mars and Jupiter. Read more
New analysis of Lutetia finds evidence for molten interior.
On July 10, 2010, the European Space Agency's Rosetta probe flew by the asteroid 21 Lutetia, which at the time was the largest asteroid ever to have been visited by a spacecraft. The fly-by occurred 282 million miles from Earth; close-up images taken by the probe revealed cracks and craters running across Lutetia's surface, evidence of the asteroid's long and battered history. Now an international team of researchers from France, Germany, the Netherlands and the United States has analysed Lutetias surface images, and found that underneath its cold and cracked exterior, the asteroid may in fact have once harboured a molten-hot, metallic core. The findings suggest that Lutetia, despite billions of years of impacts, may have retained its original structure - a preserved remnant of the very earliest days of the solar system. Read more