Earth’s Muddy Origins

Planets like Earth may have been built not from the impact of rocky asteroids, but by large balls of warm mud colliding.

Written by Nadia Blackshaw

An artist’s impression of a collision between asteroids, the process thought to result in the formation of planets like Earth.
Credit: NASA/JPL-Caltech


New research challenges the view that planets like Earth began as rocky asteroids. Instead, it suggests that many of the rocky planets were created by gigantic balls of warm mud.

The study was carried out to try and gain a better understanding of the formation of smaller planets that later became the terrestrial planets we see today.

“The assumption has been that hydrothermal alteration was occurring in certain classes of rocky asteroids with material properties similar to meteorites,” says Bryan Travis, session scientist at the Planetary Science Institute and co-author on the paper.

“However, these bodies would have accreted as a high-porosity aggregate of igneous clasts and fine-grained primordial dust, with ice filling much of the pore space. Mud would have formed when the ice melted from heat released from decay of radioactive isotopes, and the resulting water mixed with fine-grained dust.”


A temperature map (in degrees Celsius) showing mud convection in a medium-sized asteroid. The map was simulated using the Mars and Asteroids Global Hydrology Numerical Model.
Credit: Planetary Science Institute


Using his Mars and Asteroids Global Hydrology Numerical Model (MAGHNUM) Travis carried out computer simulations of mudflow and movement of a distribution of rock grain sizes in carbonaceous chondrite asteroids.

These C chondrites include some of the most primitive meteorites known, perfect candidates for asteroids that delivered water and organic material to planets, allowing them to become habitable.

The results of simulations showed many of these early asteroids might have begun as large convecting balls of mud, not consolidated rock as originally thought.

This paper could lead to new approaches in searching for habitable planets and change how researchers view the acquisition of water and organic substances in our Solar System.


Carousel Image: The Black Sea captured by the Moderate Resolution Imaging Spectroradiometer on NASA’s Aqua satellite.
Credit: Norman Kuring, NASA’s Ocean Biology Processing Group
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