MIT study redefines the role of meteorites in the formation of the early solar system

Artist's impression of two protoplanets colliding (Image: NASA/California Institute of Technology)

Until now, it has been generally accepted that a meteor constitutes a time capsule – a relic of the early creation of the solar system that has fallen to Earth, allowing us to delve into the distant past by looking at the composition of the essentially unchanged material that formed the basis of planetary formation. However, a new study carried out by researchers from MIT and Purdue University seeks to challenge the established belief, asserting that rather than representing the kernel of planetary creation, that they are instead a by-product of the violent and often cataclysmic process.

The new research revolves around the creation of tiny spherical grains known as chondrules, that are present in meteorites. Chondrules are formed where molten droplets cool, leaving behind a glassy residue. The established theory on planetary formation is that the chondrules (then molten droplets), came into contact with gas and dust particles, resulting in larger clumps of matter that would form the basis for the planetary bodies that we have today.

However, this established view of the formation of the early solar system has been thrown into doubt by a series of complex computer simulations run by researchers from MIT and Purdue University. The simulations suggest that planetary bodies the size of the moon existed prior to the creation of the earliest chondrules, and that it was the enormous pressures produced by a collision between two such bodies that were responsible for the formation of the glassy spheres.

According to the research, a cataclysmic clash between the protoplanets would produce enough force to melt a fraction of the material, sending a molten plume jetting out into space, whereupon it would cool, and adhere to the surface of what would eventually become meteorites.

Whilst the new simulations may disprove the current leading theory on the role of meteorites in planetary creation, it provides valuable insight into this formative period. We now know that the period in which the early solar system was formed, was much more violent than previously believed. During the simulations, it was found that the planetary bodies would have to strike each other at a rate of 2.5 km (1.6 miles) per second to produce an impact plume with molten droplets that would cool at the correct rate to create chondrules with the characteristics we observe today.

"Chondrules were long viewed as planetary building blocks," states Maria Zuber, Professor of Geophysics and MIT’s vice president for research. "It’s ironic that they now appear to be the remnants of early protoplanetary collisions."

Source: MIT

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