New Study Finds Venus' Atmosphere is a Consequence of Ancient "Earth-Like" Plate Tectonics

WASHINGTON and HOUSTON, Oct. 26, 2023 /PRNewswire/ -- A paper published today in Nature Astronomy indicates that Venus-type atmospheres are potentially a consequence of early phases of plate tectonics. The lead author on this paper is Universities Space Research Association's Dr. Matthew Weller at the Lunar and Planetary Institute.

Of all the first-order questions about the evolution of Venus, perhaps the most significant centers on the apparent divergence between the sibling terrestrial planets of Venus and Earth. Despite broad similarities in mass and size to Earth, Venus shows no clear evidence of plate tectonics recorded on its young surface, and Venus' atmosphere is strikingly different.

Venus is shrouded by a thick carbon dioxide-dominated atmosphere resulting in an extreme greenhouse climate with surface temperatures exceeding 800 degrees Fahrenheit. A planet's atmosphere is fundamentally linked to its interior through melting and outgassing. As a result, Venus' atmosphere offers important constraints on the planet's tectonic evolution.

Researchers at the Lunar and Planetary Institute (LPI), Brown University, and Purdue University compared the current venusian atmosphere with atmospheres generated by numerical experiments of long-term thermal-chemical-tectonic evolution. The study finds that a continuous single-plate stagnant lid regime operating since antiquity cannot explain present-day observed atmospheric abundances of nitrogen (roughly 3.5 times greater than Earth's atmospheric nitrogen) nor can it explain carbon dioxide (roughly 230,000 times greater than Earth's atmospheric carbon dioxide). Instead, the venusian atmosphere requires volcanic outgassing in an early phase of plate tectonic-like activity. Venus' atmosphere then is the result of a great tectonic-climatic transition, from an early phase of plate-tectonic-like activity that lasted for at least one billion years followed by the current period of reduced outgassing rates, called a "stagnant lid" mode.

"One of the big-picture takeaways is that we very likely had two planets at the same time in the same solar system operating in a plate tectonic regime — the same mode of tectonics that allowed for the life that we see on Earth today," says Dr. Matthew Weller, lead author of the study and Urey Fellow at the LPI. Eventually, however, plate tectonics ended on Venus, possibly due to both the loss of water and the planet's atmosphere becoming too hot and thick from the outgassing, drying up the necessary ingredients that make tectonic movements possible.

The authors suggest that the details of how this happened may hold important implications for Earth's future.

"That's going to be the next critical step in understanding Venus, its evolution, and ultimately the fate of the Earth," Weller said. "What conditions will force us to move in a Venus-like trajectory and what conditions could allow Earth to remain habitable?"

About USRA 
Founded in 1969, under the auspices of the National Academy of Sciences at the request of the U.S. Government, the Universities Space Research Association (USRA) is a nonprofit corporation chartered to advance space-related science, technology, and engineering. USRA operates scientific institutes and facilities and conducts other major research and educational programs. USRA engages the university community and employs in-house scientific leadership, innovative research and development, and project management expertise. More information about USRA is available at www.usra.edu. 

About LPI
The Lunar and Planetary Institute (LPI), operated by Universities Space Research Association, was established during the Apollo program in 1968 to foster international collaboration and to serve as a repository for information gathered during the early years of the space program. Today, the LPI is an intellectual leader in lunar and planetary science. The Institute serves as a scientific forum attracting world-class visiting scientists, postdoctoral fellows, students, and resident experts; supports and serves the research community through newsletters, meetings, and other activities; collects and disseminates planetary data while facilitating the community's access to NASA astromaterials samples and facilities; engages and excites the public about space science; and invests in the development of future generations of scientists. The research carried out at the LPI supports NASA's efforts to explore the solar system. More information about LPI is available at www.lpi.usra.edu.

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SOURCE Universities Space Research Association