Can the inner dynamics of super-Earth prepare the ground for habitability?

New research led by Yingwei Fei of Carnegie provides a framework for understanding the interiors of super-Earths – rocky exoplanets between 1.5 and 2 times the size of our home planet – which is a prerequisite for assessing their potential for development. ‘habitability. Planets of this size are among the most abundant of exoplanetary systems. The article is published in Nature communications.

“Although observations of the atmospheric composition of an exoplanet are the primary means of searching for signatures of life beyond Earth, many aspects of the habitability of a planet’s surface are influenced by what occurs. passes beneath the planet’s surface, and this is where researcher Carnegie’s long-standing expertise in the properties of rocky materials under extreme temperatures and pressures comes into play, ”explained Richard Carlson, director of the laboratory Earth and planets.

On Earth, the inner dynamics and structure of the silicate mantle and metal core drive plate tectonics and generate the geodynamics that power our magnetic field and protect us from dangerous ionizing particles and cosmic rays. Life as we know it would be impossible without this protection. Likewise, the inner dynamics and structure of super-Earths will shape the surface conditions of the planet.

With the exciting discoveries of a variety of rocky exoplanets over the past few decades, are much more massive super-Earths capable of creating conditions for life to arise and thrive?

Knowing what is going on beneath the surface of a super-Earth is crucial in determining whether or not a distant world is capable of supporting life. But the extreme conditions of super-earth mass planetary interiors challenge researchers’ ability to probe the material properties of minerals that may exist there.

This is where laboratory mimicry comes in.

For decades, Carnegie researchers have been leaders in recreating the conditions of planetary interiors by subjecting small samples of material to immense pressures and high temperatures. But sometimes even these techniques reach their limits.

“In order to build models that allow us to understand the inner dynamics and structure of super-Earths, we need to be able to take sample data that approximates the conditions that would be found there, which could exceed 14 million. times atmospheric pressure. “Fei explained.” However, we continued to run into limitations when creating these conditions in the laboratory. “

A breakthrough came when the team – comprising Asmaa Boujibar and Peter Driscoll of Carnegie, as well as Christopher Seagle, Joshua Townsend, Chad McCoy, Luke Shulenburger and Michael Furnish of Sandia National Laboratories – gained access to the most powerful, to Magnetically controlled electric machine (Sandia’s Z Pulsed Power Facility) to directly shock a high density sample of bridgmanite – a high pressure magnesium silicate that is believed to be predominant in the mantles of rocky planets – in order to expose it to extreme conditions relevant to the interior of super-Earths.

A series of hypervelocity shock wave experiments on a material representative of the super-terrestrial mantle provided density and melting temperature measurements that will be fundamental in interpreting the observed masses and radii of super-Earths.

The researchers found that under pressures representative of super-terrestrial interiors, bridgmanite has a very high melting point, which would have important implications for interior dynamics. Under some thermal evolution scenarios, they say, massive rocky planets could have thermally driven geodynamics early in their evolution and then lose it for billions of years when cooling slows down. A sustained geodynamo could possibly be revived by the movement of lighter elements through the crystallization of the inner core.

“The ability to make these measurements is crucial to developing reliable models of the internal structure of super-Earths up to eight times the mass of our planet,” Fei added. “These results will have a profound impact on our ability to interpret observational data.”