Study Identifies Which Parts of an Asteroid Make It to Earth’s Surface

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(Photo: NASA)Scientists have only recently gotten an up-close look at asteroids, as well as the chance to examine material from them in a lab. Before that, all we had were the remains of asteroids that fell to Earth. But what part of the original space rocks are they? A new study from the SETI Institute and NASA’s Ames Research Center used advanced computer simulations to figure that out.

Asteroids are seen as an important source of information about the origins of our solar system. The composition of these objects can remain unchanged for billions of years, meanwhile weathering, oxygen exposure, and biological processes have altered everything on Earth. That’s why both NASA and the Japanese Space Agency (JAXA) are working to return asteroid samples to Earth for study. Understanding what parts of an asteroid become Earth-bound meteorites could also help with that effort. 

The study focused on an object that impacted Earth 14 years ago. The asteroid, known as 2008 TC3 was about six meters in diameter before it entered the atmosphere over the Nubian Desert of Sudan. Like most asteroids, the intense heat generated by the thickening atmosphere melted the structure and caused it to break apart into a shower of meteorites. The University of Khartoum assisted in collecting the meteorites, which were scattered over a 7 x 30 square kilometer area. 

After SETI researchers noted that larger pieces of the object were spread more widely than smaller ones, they reached out to NASA’s Asteroid Threat Assessment Project (ATAP) at Ames. Unlike most asteroids, 2008 TC3 was spotted 20 hours before it hit and was tracked all the way down. Thus, it was an ideal candidate on which to base a model. 

According to ATAP’s Darrel Robertson, a hydrodynamic model of 2008 TC3 showed that it generated a near-vacuum wake in the atmosphere as it fell. Fragments from the sides fell off first and were sucked into the wake. After that, the front began to collapse, as did the top. Because of the shape of 2008 TC3, the back and bottom sections were the last to come apart. As they were unencumbered by surrounding material, they were flung farther afield when the structure finally fractured. The widely scattered large pieces are, therefore, from this final collapse. 

The researchers found various types of meteorites in the debris, all spread out randomly. Given the results of the simulation, that suggests the original object had these materials randomly distributed as well. The results from this study could help scientists understand other meteorite falls, as well as shed light on our early exploration of intact space rocks.

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