Earth 2.0 Could be Young, Rocky Exoplanet

New research narrows down candidates for other Earths by restricting them to younger, rocky planets still capable of mantle degassing.

IMAGE: The red dwarf star TRAPPIST-1 is home to the largest group of roughly Earth-sized planets ever found in a single stellar system with seven rocky siblings including four in the habitable zone. But at around 8 billion years old, these worlds are roughly 2 billion years older than the most optimistic degassing lifetime predicted by this study and unlikely to support a temperate climate today. CREDIT: NASA/JPL-Caltech

A lot of time has been spent talking about the so-called Goldilocks Zone when it comes to the search for Earth 2.0. The Kepler mission was designed basically to do just that — stare at stars similar to our Sun and look for rocky planets in that region where liquid water could exist. But we still haven’t found an exoplanet that matches our conditions. And it’s not even about the possibility of liquid water anymore. After all, we have liquid water beneath icy crusts on worlds in our solar system that definitely aren’t in the Goldilocks Zone.

So now, researchers at the Southwest Research Institute have led new work on narrowing down candidates for other Earths. Their results were published in The Astrophysical Journal Letters and reason that younger planets make better targets because they still have the right amounts of radioactive isotopes to keep the planet warm. And that would happen through a process called mantle degassing, where the radioactive heat causes convection in the mantle, and that convection allows carbon dioxide to vent from volcanoes.