* Astronomy

Title: Chelyabinsk meteorite explains unusual spectral properties of Baptistina Asteroid Family
Author: Vishnu Reddy, Juan Sanchez, William Bottke, Ed Cloutis, Matt Izawa, Dave O'Brien, Paul Mann, Matt Cuddy, Lucille Le Corre, Michael Gaffey, Gary Fujihara

We investigated the spectral and compositional properties of Chelyabinsk meteorite to identify its possible parent body in the main asteroid belt. Our analysis shows that the meteorite contains two spectrally distinct but compositionally indistinguishable components of LL5 chondrite and shock blackened/impact melt material. Our X-ray diffraction analysis confirms that the two lithologies of the Chelyabinsk meteorite are extremely similar in modal mineralogy. The meteorite is compositionally similar to LL chondrite and its most probable parent asteroid in the main belt is a member of the Flora family. Intimate mixture of LL5 chondrite and shock blackened/impact melt material from Chelyabinsk provides a spectral match with (8) Flora, the largest asteroid in the Flora family. The Baptistina family and Flora family overlap each other in dynamical space. Mineralogical analysis of (298) Baptistina and 9 small family members shows that their surface compositions are similar to LL chondrites, although their absorption bands are subdued and albedos lower when compared to typical S-type asteroids. A range of intimate mixtures of LL5 chondrite and shock blackened/impact melt material from Chelyabinsk provides spectral matches for all these BAF members. We suggest that the presence of a significant shock/impact melt component in the surface regolith of BAF members could be the cause of lower albedo and subdued absorption bands. The parent asteroid of BAF was either a member of the Flora family or had the same basic composition as the Floras (LL Chondrite). The shock pressures produced during the impact event generated enough impact melt or shock blackening to alter the spectral properties of BAF, but keep the BAF composition largely unchanged.

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Divers working at a Russian lake have recovered what may be a 570kg chunk of the space rock that exploded over Chelyabinsk earlier this year.
The object is thought to have plunged into Lake Chebarkul in central Russia leaving a 6m-wide hole in the ice.
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NASA's Suomi (NPP) Satellite Detects A Plume From A Meteor

Some of the surviving pieces of the Chelyabinsk meteor (or bolide) fell to the ground near Chebarkul, Russia. But the explosion also injected hundreds of tons of dust into the stratosphere, allowing a NASA-NOAA satellite to make unprecedented measurements of a thin but cohesive and persistent dust belt.

Astronomers identify 20 asteroids on similar path to Russian meteor

The house-sized rock that exploded spectacularly in the skies near Chelyabinsk, Russia, in February may have been a member of a gang of asteroids that still poses a threat to Earth, a new study says. The evidence is circumstantial, but future observations could help to settle the question.
The best sibling candidate, for instance, is a 200-metre-wide asteroid known as 2011 EO40, whose orbit was calculated from observations taken over just 34 days. That is too short a time to be able to pinpoint its position in the future, says Jon Giorgini, a senior analyst in the Solar System Dynamics Group at NASA's Jet Propulsion Laboratory in Pasadena, California. For that, researchers would need observations taken over the asteroid's two-year orbit, he says.
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