Life on Venus? Tectonic clues point to a habitable past

Simulations created by a research team led by Brown provide evidence of that Venus Once upon a time there was plate tectonics – which opens the door to the possibility of early life on the planet and insights into its history.

According to scientists, Venus, a burning wasteland of a planet, may have once had the tectonic plate movements believed to have occurred at the beginning of Earth, a new study has found. The discovery sets up stunning scenarios about the possibility of early life on Venus, its evolutionary past and the history of the Solar System.

Writing in a scientific journal Natural AstronomyA team of scientists led by Brown University researchers has used Venus’s atmospheric data and computer modeling to show that the combination of the planet’s current atmosphere and surface pressure is possible only as a result of plate tectonics, a process. The pushing, pulling, and sliding of multiple continental plates under each other is critical to life.

On Earth, this process intensified over billions of years, forming new continents and mountains, and led to chemical reactions that stabilized the surface temperature of the planet, resulting in a more favorable environment for the development of life.

Although Venus is a burning wasteland, the planet is often referred to as Earth’s sister due to similarities in size, mass, density, and size. Credit: NASA/JPL

Divergent Venus and Earth’s Geological Trajectories

Earth’s nearest neighbor, Venus, on the other hand, went in the opposite direction and has surface temperatures hot enough to melt lead today. One explanation is that the planet has always been thought to have a so-called „stagnant lid,” meaning its surface has only a plate with little yield, movement, and release of gases into the atmosphere.

The new paper says this isn’t always the case. To account for the abundance of nitrogen and carbon dioxide in Venus’ atmosphere, the researchers conclude that Venus must have undergone plate tectonics after the planet formed, about 4.5 billion to 3.5 billion years ago. The paper suggests that this early tectonic movement, like Earth’s, would have been limited by the number of moving plates and how much they shifted. This would have happened on Earth and Venus at the same time.

„What makes a big picture is that two planets in the same solar system at the same time were operating in a plate tectonic regime — the same mode of tectonics that allowed for the life we ​​see on Earth today,” he said. Matt Weller, lead author of the study, completed the work while he was a postdoctoral researcher at Brown and is now at the Lunar and Planetary Institute in Houston.

Implications for ancient life and planetary life

This raises the possibility of microbial life on ancient Venus and that at one point the two planets – in the same solar neighborhood, are the same size and have the same mass, density and size – were more similar than before. I thought before digressing.

The work also highlights the possibility that plate tectonics on planets may have evolved over time – and therefore, possibly life itself.

„So far we’ve thought about tectonic status in binary terms: it’s true or it’s false, and it’s true or false for the duration of the planet,” said study co-author Alexander Evans, assistant professor of Earth. , Environmental and Planetary Sciences at Brown. „This shows that planets can shift in and out of different tectonic states and that this may actually be more common. Earth may be an exoplanet. It may have planets that can shift in and out of habitability, rather than being continuously habitable.

Importance of Atmospheric Research

That concept is important to consider when scientists look to understand nearby moons ThursdayIn Europe, it has proven Earth has plate tectonics — and distant exoplanets, according to the paper.

The researchers, who initially began the work as a way to show that the atmospheres of distant exoplanets can be powerful markers of their early histories, decided to probe the point closer to home.

They used current data on Venus’ atmosphere as the endpoint of their models and began by assuming that Venus had a stagnant lid throughout its entire existence. They quickly saw that simulations recreating the planet’s current atmosphere did not match where the planet is now, based on the amount of nitrogen and carbon dioxide in the current atmosphere and the resulting surface pressure.

Researchers simulated what must have happened on the planet to get to where it is today. They eventually matched the numbers exactly when we calculated the limited tectonic motion early in Venus’ history, followed by the stagnant lid model that exists today.

Overall, the team believes the work provides proof of concept about atmospheres and their ability to provide insights into the past.

„We’re still in this paradigm where we use the surfaces of planets to understand their history,” Evans said. „We show for the first time that atmospheres may be the best way to understand the ancient history of planets, which are often not preserved on the surface.”

DAVINCI will send a meter-diameter probe to brave the high temperatures and pressures near the surface of Venus, probing the atmosphere from above the clouds to near the surface of a landmass that used to be a continent. During its final kilometer free-fall descent (artist’s impression shown here), the probe will capture spectacular images and chemical measurements of Venus’ deep atmosphere for the first time. Credit: NASA/GSFC/CI Laboratories

Future research and results

Upcoming missions by NASA’s DaVinci measuring gases in the Venusian atmosphere will help confirm the study’s findings. Meanwhile, the researchers plan to delve deeper into a key question the paper raises: What happened to plate tectonics on Venus? The theory in the paper is that the planet eventually became too hot and its atmosphere too thick, drying out the material needed for tectonic movement.

„Venus basically ran out of juice to some extent, and that put the brakes on the process,” said Daniel Ibarra, a professor in Brown’s Department of Earth, Environmental and Planetary Sciences and a co-author on the paper.

The details of how this happened could have important implications for Earth, researchers say.

„This will be an important next step in understanding Venus, its evolution and ultimately the fate of Earth,” Weller said. „What conditions would prompt us to take a Venus-like trajectory, and what conditions would allow Earth to be habitable?”

Note: „Venus’ Atmospheric Nitrogen Explained by Ancient Plate Tectonics” Matthew P. Weller, Alexander J. Evans, Daniel E. Ibarra and Alexandria v. Johnson, 26 Oct. 2023, Natural Astronomy.
DOI: 10.1038/s41550-023-02102-w

The study also included Alexandria Johnson of Purdue University. supported it NASAIn Solar System Project.