A “super-Earth” is an exoplanet that is about 1.5 to 2 times larger than Earth. Having a rocky surface is essential for a planet to have a habitable environment for Life. Among the exoplanets that have been discovered, a large number of planets are of the super-Earth type. Are these planets suitable for life?
“While observing the structure of exoplanet atmospheres is the first way to look for extraterrestrial life, the surface environment on many planets is influenced by their subsurface conditions.” says Richard Carlson, head of the Earth and Planets Laboratory at the Carnegie Institute of Technology.
In the case of Earth, the internal dynamics and structure of the silicate mantle and metallic nuclei are the drivers of crustal motion and generate the Earth’s magnetic field, which protects life from high-energy cosmic rays. Without this magnetic shield, the Earth would not be a habitable environment.
Similarly, scientists believe that probing the dynamical cycles and structure of the super-Earth’s interior is an important way to understand its surface environment and, subsequently, to infer whether the planet is habitable.
A study published Feb. 9 in the journal Nature Communications suggests a way to build a laboratory simulation of such planets’ core environments.
The Carnegie Institute of Technology has been conducting research to simulate planetary interiors for decades. They subject small samples of material to high pressures and temperatures, but there are times when these techniques hit a bottleneck.
Yingwei Fei of the Carnegie Institute of Technology says, “Super-Earth internal environmental pressures can exceed 14 million atmospheres, and to simulate these environments in the lab, we constantly run into difficulties.”
They recently had a breakthrough. With Sandia National Laboratories’ Z Pulsed Power Facility, the world’s largest generator of high-frequency electromagnetic waves for testing materials at extreme temperatures and pressures, they were finally able to directly impact a sample of high-density bridgmanite, a magnesium silicate at high pressure.
Scientists believe that magnesium silicate in high pressure state is the main material of Super Earth mantle layer. The experimental results show that in the super-Earth internal environment, Bridgmanite has a high melting point, which plays an important role in the internal dynamical circulation mechanism of the planet.
According to the laws of thermodynamic evolution of planetary interiors, researchers believe that these super-Earths may have had the power to support the planet’s magnetic field at the beginning of their existence, but disappeared after cooling down, and were insufficient to support the magnetic field for billions of years. Later, as the core crystallizes, with the movement of some lighter elements inside, this dynamical mechanism will be restored, restarting the magnetic field.
Yingwei Fei said, “Having the ability to make these measurements is a key part of building reliable models of the internal environment for super-Earths of up to eight times the mass of Earth, and these results have profound implications for our ability to interpret the observational data.”
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