Asteroids Don’t Break Up Like You Think They Do: Study

Wednesday, December 31, 2014

Asteroids Don’t Break Up Like You Think They Do: Study

Asteroids Don’t Break Up Like You Think They Do: Study:

Artist’s impression of an asteroid breaking up. Credit: NASA/JPL-Caltech

The early Solar System was a shooting gallery. Smaller-body collisions happened far more frequently than we see it today, pockmarking the Moon and Mercury. On a larger scale, simulation show the Earth came close to blowing apart when a Mars-sized object crashed into us long ago.

So we’d be forgiven for thinking that it’s asteroid collisions that cause these tiny bodies to break up, given their numbers and the history of our neighborhood. But it turns out, a new study says, that the larger asteroids likely have another way of coming apart.

“For asteroids about 100 meters [328 feet] in diameter collisions are not the primarily cause of break ups – rapid rotation is,” the Smithsonian Astrophysical Observatory stated.

“Moreover, because the rate of collisions depends on the numbers and sizes of objects but rotation does not, their results are in strong disagreement with previous models of collisionally-produced small asteroids.”

Most near-Earth asteroids fall into three classes named after the first asteroid discovered in that class. Apollo and Aten asteroids cross Earth’s orbit; Amors orbit just beyond Earth but cross Mars’ orbit. Credit: Wikipedia

It turns out that rotation has a strong effect on such a small body. First, the asteroid is emitting stuff that can produce a spin — water evaporating, or its surface expanding as heat from the Sun strikes it. Also, the Sun’s pressure on the asteroid creates a rotation. Between these different effects, at the right (or wrong) moment it can cause a catastrophic breakup.

As a simulation (coupled with observations from the Pan-STARRS telescope), the research is not done with complete certainty. But the model shows 90% confidence that asteroids in the so-called “main belt” (between Mars and Jupiter”) experience disruptions in this way, at least once per year.

The research was published in the journal Icarus and is also available in preprint version on Arxiv. It was led by Larry Denneau at the University of Hawaii.

Source: Smithsonian Astrophysical Observatory

About Elizabeth Howell

Elizabeth Howell is the senior writer at Universe Today. She also works for Space.com, Space Exploration Network, the NASA Lunar Science Institute, NASA Astrobiology Magazine and LiveScience, among others. Career highlights include watching three shuttle launches, and going on a two-week simulated Mars expedition in rural Utah. You can follow her on Twitter @howellspace or contact her at her website.

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The National Aeronautics and Space Administration (NASA) is the United States government agency responsible for the civilian space program as well as aeronautics and aerospace research. President Dwight D. Eisenhower established the National Aeronautics and Space Administration (NASA) in 1958 with a distinctly civilian (rather than military) orientation encouraging peaceful applications in space science. The National Aeronautics and Space Act was passed on July 29, 1958, disestablishing NASA's predecessor, the National Advisory Committee for Aeronautics (NACA). The new agency became operational on October 1, 1958.

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Wednesday, December 31, 2014