Meteorite just one piece of an unknown celestial body

December 15, 2010
Meteorite just one piece of an unknown celestial body

(PhysOrg.com) -- Scientists from all over the world are taking a second, more expansive, look at the car-sized asteroid that exploded over Sudan's Nubian Desert in 2008. Initial research was focused on classifying the meteorite fragments that were collected two to five months after they were strewn across the desert and tracked by NASA's Near Earth Object astronomical network. Now in a series of 20 papers for a special double issue of the journal Meteoritics and Planetary Science, published on December 15, researchers have expanded their work to demonstrate the diversity of these fragments, with major implications for the meteorite's origin.

In the first round of research, Carnegie Geophysical scientist Doug Rumble, in collaboration with Muawia Shaddad of the University of Khartoum, examined one fragment of the asteroid, called 2008 TC3, and determined that it fell into a very rare category of meteorite called ureilites. Ureilites have a very different composition from most other meteorites. It has been suggested that all members of this meteoric family might have originated from the same source, called the ureilite parent body, which could have been a proto-planet.

Now Rumble has expanded his work to examine 11 meteorite fragments, focusing on the presence of . Isotopes are atoms of the same element that have extra in their .

Rumble explains: "Oxygen isotopes can be used to identify the meteorite's parent body and determine whether all the fragments indeed came from the same source. Each parent body of meteorites in the Solar System, including the Moon, Mars, and the large asteroid Vesta, has a distinctive signature of oxygen isotopes that can be recognized even when other factors, such as and type of rock, are different."

Rumble and his team prepped tiny crumbs of these 11 fragments and loaded them into a reaction chamber where they were heated with a laser and underwent to release oxygen and then used another device, called a mass spectrometer, to measure the concentrations of these oxygen isotopes. Results showed that the full range of oxygen isotopes known to be present in ureilites were also present in the studied fragments.

"It was already known that the fragments in the Nubian Desert came from the same asteroid. Taking that into account, these new results demonstrate that the asteroid's source, the ureilite parent body, also had a diversity of oxygen isotopes," says Rumble.

The diversity of oxygen isotopes found in ureilites probably arises from the circumstances of the parent this body's formation. Rumble theorizes that the rock components of this parent body were heated to the point of melting and then cooled into crystals so quickly that the oxygen isotopes present could not come to an equilibrium distribution throughout.

Together the collection of 20 papers published in Meteoritics and Planetary Science offer enormous insight about the formation and composition of ureilites and their hypothesized parent body.

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Yellowdart
1 / 5 (2) Dec 15, 2010
Taking that into account, these new results demonstrate that the asteroid's source, the ureilite parent body, also had a diversity of oxygen isotopes," says Rumble.


Sometimes, the answer is right underneath their noses.

Quantum_Conundrum
1.8 / 5 (6) Dec 15, 2010
Each parent body of meteorites in the Solar System, including the Moon, Mars, and the large asteroid Vesta, has a distinctive signature of oxygen isotopes that can be recognized even when other factors, such as chemical composition and type of rock, are different


I don't see how this could be possible, because virtually nothing in the solar system has uniform composition. A meteor that orginated from the Martian Poles would be expected to be different from one originating from the equator.

A meteor originating from Canada would be expected to be different than one originating from the Gulf of Mexico, assuming anything was ever ejected to space from any of those craters.

Planets don't have uniform compositions, they have lava flows, they have sedimentary and metamorphic rocks, etc, and all of these would have different mineralogy even for the same parent object.
Quantum_Conundrum
1.5 / 5 (6) Dec 15, 2010
So anyway, let's just play along.

If everything is as old as the geologists and astronomers claim it is, then that means the Sun has made roughly 13.3 complete orbits of the Milky Way's center of gravity since the Earth existed.

This means the Solar System would have likely passed through many, many different types of galactic nebulae with varying compositions during that time. These nebulae would influence the isotope ratio in various rocks at various ages because the gases would fall to the planets atmosphere or surface as micro meteors and eventually be incorporated in soils. For planets like earth, the oldest of these would have been subducted into the mantle already, and possibly even being reconstituted in volcanoes as lava.

Generally, it's just an overly simplistic model for finding the origin of a meteorite.

I think it is a lot more fruitful if they can COMBINE such an approach with the obvious regression of the meteorite's orbit, but alone it's nearly useless.
Silverhill
4 / 5 (2) Dec 15, 2010
Isotopes are atoms of the same element that have extra neutrons in their nuclei.
Or fewer neutrons. Oxygen nuclei can have as few as 4 or as many as 16 neutrons.
Shootist
3 / 5 (2) Dec 16, 2010
Planets don't have uniform compositions,


Mars, Earth and Vesta share the same ratio of Oxygen isotopes. The Oxygen isotope ratios of other bodies in the Solar System (the Moon for instance), differ from the Earth, Mars, Vesta baseline.

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