Radioactive elements may be crucial to the habitability of rocky planets
10-NOV-2020
Earth-size planets can have varying amounts of radioactive elements, which generate internal heat that drives a planet's geological activity and magnetism
UNIVERSITY OF CALIFORNIA - SANTA CRUZ
These illustrations show three versions of a rocky planet with different amounts of internal heating from
radioactive elements. The middle planet is Earth-like, with plate tectonics and an internal dynamo generating
a magnetic field. The top planet, with more radiogenic heating, has extreme volcanism but no dynamo or
magnetic field. The bottom planet, with less radiogenic heating, is geologically 'dead,' with no volcanism.
CREDIT
Illustrations by Melissa Weiss
The amount of long-lived radioactive elements incorporated into a rocky planet as it forms may be a crucial factor in determining its future habitability, according to a new study by an interdisciplinary team of scientists at UC Santa Cruz.
That's because internal heating from the radioactive decay of the heavy elements thorium and uranium drives plate tectonics and may be necessary for the planet to generate a magnetic field. Earth's magnetic field protects the planet from solar winds and cosmic rays.
Convection in Earth's molten metallic core creates an internal dynamo (the "geodynamo"
that generates the planet's magnetic field. Earth's supply of radioactive elements provides more than enough internal heating to generate a persistent geodynamo, according to Francis Nimmo, professor of Earth and planetary sciences at UC Santa Cruz and first author of a paper on the new findings, published November 10 in Astrophysical Journal Letters.
"What we realized was that different planets accumulate different amounts of these radioactive elements that ultimately power geological activity and the magnetic field," Nimmo explained. "So we took a model of the Earth and dialed the amount of internal radiogenic heat production up and down to see what happens."
More:
https://www.eurekalert.org/pub_releases/2020-11/uoc--rem111020.php
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