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High-resolution images of the surface of asteroid Itokawa from the Hayabusa mission reveal it to be covered with unconsolidated millimeter-sized and larger gravels. Locations and morphologic characteristics of this gravel indicate that Itokawa has experienced considerable vibrations, which have triggered global-scale granular processes in its dry, vacuum, microgravity environment. These processes likely include granular convection, landslide-like granular migrations, and particle sorting, resulting in the segregation of the fine gravels into areas of potential lows. Granular processes become major resurfacing processes because of Itokawa's small size, implying that they can occur on other small asteroids should those have regolith.
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http://dx.doi.org/10.1126/science.1134390 | DOI Listing |
Nat Commun
July 2024
Dipartimento di Scienze e Tecnologie Aerospaziali, Politecnico di Milano-Bovisa Campus, Milano, Italy.
Asteroids smaller than 10 km are thought to be rubble piles formed from the reaccumulation of fragments produced in the catastrophic disruption of parent bodies. Ground-based observations reveal that some of these asteroids are today binary systems, in which a smaller secondary orbits a larger primary asteroid. However, how these asteroids became binary systems remains unclear.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
January 2023
John de Laeter Centre, Curtin University, Bentley WA 6102, Australia.
Rubble piles asteroids consist of reassembled fragments from shattered monolithic asteroids and are much more abundant than previously thought in the solar system. Although monolithic asteroids that are a kilometer in diameter have been predicted to have a lifespan of few 100 million years, it is currently not known how durable rubble pile asteroids are. Here, we show that rubble pile asteroids can survive ambient solar system bombardment processes for extremely long periods and potentially 10 times longer than their monolith counterparts.
View Article and Find Full Text PDFNPJ Microgravity
August 2022
Experimentelle Astrophysik, Universität Duisburg-Essen, Lotharstr. 1-21, 47057, Duisburg, Germany.
The ballistic sorting effect has been proposed to be a driver behind the observed size sorting on the rubble pile asteroid Itokawa. This effect depends on the inelasticity of slow collisions with granular materials. The inelasticity of a collision with a granular material, in turn, depends on grain size.
View Article and Find Full Text PDF