Chelyabinsk meteorite had previous collision or near miss (Update)

Aug 26, 2013
Fragment of Chelyabinsk meteorite, showing the fusion crust -- the result of a previous collision or near miss with another planetary body or with the sun. Credit: Dr. Victor Sharygin

The Chelyabinsk meteorite either collided with another body in the solar system or came too close to the Sun before it fell to Earth, according to research announced today at the Goldschmidt conference in Florence.

A team from the Institute of Geology and Mineralogy (IGM) in Novosibirsk have analysed fragments of the meteorite, the main body of which fell to the bottom of the Chebarkul Lake near Chelyabinsk on 15 February this year.

Although all of the fragments are composed of the same minerals, the structure and texture of some fragments show that the meteorite had undergone an intensive melting process before it was subjected to extremely high temperatures on entering the Earth's atmosphere.

"The meteorite which landed near Chelyabinsk is a type known as an LL5 chondrite and it's fairly common for these to have undergone a melting process before they fall to Earth," says Dr Victor Sharygin from IGM, who is presenting the research at the Goldschmidt conference. "This almost certainly means that there was a collision between the Chelyabinsk meteorite and another body in the solar system or a near miss with the Sun."

Based on their colour and structure, the IGM researchers have divided the meteorite fragments into three types: light, dark and intermediate. The lighter fragments are the most commonly found, but the dark fragments are found in increasing numbers along the meteorite's trajectory, with the greatest number found close to where it hit the Earth.

The dark fragments include a large proportion of fine-grained material, and their structure, texture and mineral composition shows they were formed by a very intensive melting process, likely to have been either a collision with another body or proximity to the Sun. This material is distinct from the 'fusion crust' - the thin layer of material on the surface of the meteorite that melts, then solidifies, as it travels through the Earth's atmosphere.

"Of the many fragments we've been analysing, only three dark samples show strong evidence of earlier metamorphism and melting," says Dr Sharygin. "However, many fragments of the meteorite were picked up by members of the public, so it's impossible to say how large a portion of the meteorite was affected. We hope to find out more once the main body of the meteorite is raised from Chebarkul Lake."

The fine-grained material of the dark fragments also differs from the other samples as it commonly contains spherical 'bubbles' which are either encrusted with perfect crystals of oxides, silicates and metal or filled with metal and sulfide.

Surprisingly, the IGM team also found small quantities of platinum group elements in the meteorite's fusion crust. The team are only able to identify these elements as an alloy of osmium, iridium and platinum, but its presence is unusual as the fusion crust is formed over too short a time period for these elements to easily accumulate.

"Platinum group elements usually occur as trace elements dispersed in meteorite minerals, but we found them as a nanometer-sized mineral (100-200 nm) in a metal-sulfide globule in the fusion crust of the Chelyabinsk meteorite," explains Dr Sharygin. "We think the appearance (formation) of this platinum group mineral in the fusion crust may be linked to compositional changes in metal-sulfide liquid during remelting and oxidation processes as the meteorite came into contact with atmospheric oxygen."

The findings are part of ongoing research into the meteorite, using a scanning microscope, electron microprobe and gas chromatography-mass spectrometry, through which the IGM team are producing a detailed mineral analysis of the Chelyabinsk meteorite.

Explore further: NASA selects instruments to track climate impact on vegetation

Provided by European Association of Geochemistry

4.6 /5 (14 votes)
add to favorites email to friend print save as pdf

Related Stories

Scientists claim discovery of Russian meteorites

Feb 18, 2013

Scientists announced the discovery Monday of dozens of tiny fragments of a massive meteor whose ground-shaking shockwave hurt 1,200 people and damaged buildings across five regions of Russia.

Big meteorite chunk found in Russia's Ural Mountains

Feb 27, 2013

Scientists and meteorites hunters have been on a quest to find bits of rock from the asteroid exploded over the city of Chelyabinsk in Russia on February 15. More than 100 fragments have been found so far ...

Russia halts search for meteorite

Feb 17, 2013

Russian authorities halted their search Sunday for the meteorite that spectacularly struck the Urals last week, leaving about 1,200 people injured and damaging several thousand buildings.

Russia meteor not linked to asteroid flyby

Feb 17, 2013

New information provided by a worldwide network of sensors has allowed scientists to refine their estimates for the size of the object that entered that atmosphere and disintegrated in the skies over Chelyabinsk, ...

Recommended for you

Lifetime of gravity measurements heralds new beginning

50 minutes ago

Although ESA's GOCE satellite is no more, all of the measurements it gathered during its life skirting the fringes our atmosphere, including the very last as it drifted slowly back to Earth, have been drawn ...

NASA's IceCube no longer on ice

4 hours ago

NASA's Science Mission Directorate (SMD) has chosen a team at NASA's Goddard Space Flight Center in Greenbelt, Maryland, to build its first Earth science-related CubeSat mission.

Tidal forces gave moon its shape, according to new analysis

19 hours ago

The shape of the moon deviates from a simple sphere in ways that scientists have struggled to explain. A new study by researchers at UC Santa Cruz shows that most of the moon's overall shape can be explained by taking into ...

User comments : 2

Adjust slider to filter visible comments by rank

Display comments: newest first

cantdrive85
1 / 5 (10) Aug 27, 2013
the structure and texture of some fragments show that the meteorite had undergone an intensive melting process

fine-grained material, and their structure, texture and mineral composition shows they were formed by a very intensive melting process,

'fusion crust'

contains spherical 'bubbles' which are either encrusted with perfect crystals of oxides, silicates and metal or filled with metal and sulfide.

alloy of osmium, iridium and platinum, but its presence is unusual as the fusion crust is formed over too short a time period for these elements to easily accumulate.


All of this evidence is screaming a common origin, plasma (electric) arc discharge.

JohnGee
3.2 / 5 (9) Aug 27, 2013
No it's not.