Can the Earth’s inward dynamics set the table for habitability?

Can the Earth's inward dynamics set the table for habitability?

An illustration showing how a combination of static high-pressure synthetic techniques and dynamic methods enabled the researchers to investigate the magnesium silicate bridgmanite, which is believed to dominate the mantles of rocky planets, under extreme conditions that dominate the inside of a super mimic earth. Credit: Yingwei Fei. Sandia Z Machine Photo by Randy Montoya, Sandia National Laboratories.

New research led by Carnegie’s Yingwei Fei provides a framework for understanding the interior of super-Earths – rocky exoplanets between 1.5 and 2 times the size of our home planet – which is a prerequisite for realizing their potential for habitability. determined. Planets of this size are among the most abundant in exoplanetary systems. The paper is published in Nature communication.

“Although observations of the atmospheric composition of an exoplanet will be the first way to search for signatures of life beyond Earth, many aspects of a planet’s habitability are affected by what happens below the planet’s surface, and this is where Carnegie Researcher’s years of expertise in the properties of rocky materials come under extreme temperatures and pressures, ”explained Richard Carlson, director of the Earth and Planets Laboratory.

On Earth, the internal dynamics and structure of the silicate mantle and metal core propel plate tectonics, generating the geodynamo that drives our magnetic field and protects us from dangerous ionizing particles and cosmic rays. Life as we know it would be impossible without this protection. Similarly, the internal dynamics and structure of super-Earth will shape the surface conditions of the planet.

With exciting discoveries of a variety of rocky exoplanets in recent decades, are many more massive super-Earths capable of creating conditions that are hospitable for life to rise and flourish?

Knowledge of what lies beneath the surface of a super-Earth is crucial to determine whether a distant world is capable of housing life. But the extreme conditions of planetary interiors with a super-Earth mass challenge researchers’ ability to investigate the material properties of the minerals that may exist there.

This is where lab-based mimicry comes in.

Can the Earth's inward dynamics set the table for habitability?

An illustration by a scientist using laboratory-based techniques to investigate conditions in exoplanet interiors. Credit: Katherine Cain, Carnegie Institution of Science.

Carnegie researchers have been leaders for decades in recreating the conditions of planetary interiors by placing small samples of material under tremendous pressure and high temperatures. But sometimes even these techniques reach their limits.

“To build models that enable us to understand the internal dynamics and structure of super-Earths, we must be able to take data from samples that represent the conditions that would be found there, which are 14 million times the atmospheric pressure can exceed, approach. ‘Fei explains. “However, we still had limitations to create these conditions in the laboratory.”

A breakthrough came when the team – including Asmaa Boujibar and Peter Driscoll of Carnegie, along with Christopher Seagle, Joshua Townsend, Chad McCoy, Luke Shulenburger and Michael Furnish of Sandia National Laboratories – gained access to the world’s most powerful, magnetically driven wrist. power machine (Sandia’s Z Pulsed Power Facility) to directly shock a high density sample of bridgmanite – a high pressure magnesium silicate believed to be predominant in the mantles of rocky planets – to expose it to the extreme conditions relevant to the interior of super-Earth.

A series of shockwave experiments on hypervelocity on representative super-Earth mantle material provided density and melting temperature measurements that would be fundamental to the interpretation of the observed masses and radii of super-Earth.

According to the researchers, bridgmanite has a very high melting point under pressure that is representative of super-Earth interiors, which will have important implications for the internal dynamics. According to certain thermal evolutionary scenarios, they say, massive rocky planets may have a thermally driven geodynamo early in their evolution and then lose it billions of years if the cooling slows down. Eventually, a sustained geodynamo can be restarted by the movement of lighter elements through inner nuclear crystallization.

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


Super-Earth atmosphere explored on Sandia’s Z machine


More information:
Yingwei Fei et al. Melting and density of MgSiO3 determined by shock compaction of bridgmanite up to 1254GPa, Nature communication (2021). DOI: 10.1038 / s41467-021-21170-y

Provided by Carnegie Institution for Science

Quotation: Can inner dynamics within the earth set the table for habitability? (2021, 9 February) Retrieved 10 February 2021 from https://phys.org/news/2021-02-super-earth-interior-dynamics-table-habitability.html

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