New research suggests Earth’s sister planet may have been home to microbial life billions of years ago due to tectonic activities
The clouded globe of Venus captured by NASA's Mariner 10 spacecraft. Photo: NASA / JPL-Caltech_ Venus, often referred to as Earth’s sister planet, may have experienced tectonic activity about 4.5 billion to 3.5 billion years ago, according to a new study.
Plate tectonics may have been instrumental in creating its carbon dioxide- and nitrogen-rich atmosphere on Venus, the new report published in the journal Nature Astronomy noted. The planet’s atmospheric composition is mainly composed of carbon dioxide (96.5 per cent) and nitrogen (less than 3.5 per cent).
Plate tectonics is a scientific theory that describes how Earth’s thin outer shell is broken into big pieces called tectonic plates, which float on the planet’s mantle. Plate tectonics gave rise to oceans, continents and mountains, along with playing a critical role in nourishing life on Earth.
Read more: Venus’ volcanoes may be active, show decades-old radar images
The new findings suggest that ancient Venus may have been home to microbial life, thanks to tectonic activities. That means Earth and Venus may have been even more alike than thought.
“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,” Matthew Weller from the Lunar and Planetary Institute in Houston and lead author of the study said in a statement.
However, Weller explained that plate tectonics would have likely ended on Venus after it lost water and its atmosphere got too hot and thick. This process may have dried up the necessary ingredients that make tectonic movements possible.
Venus and Earth are about the same size, mass, density and volume. Still, Venus is the least understood of the terrestrial planets, according to the study.
Weller and his colleagues focused on the mechanisms that probably created Venus’s atmosphere, which they speculated were linked to its interior. So they compared the present-day Venusian atmosphere to those generated by computer models.
Their analysis showed that only early plate tectonics could explain the present Venus’ current atmosphere and surface pressure.
Sometime after the planet formed, about 4.5 billion to 3.5 billion years ago, plate tectonics may have existed on Venus. This early tectonic movement would have been happening on Earth and Venus simultaneously, the researchers explained.
Read more: Ancient Venus was potentially habitable for three billion years: Study
Venus may have transitioned from limited tectonic movement early in its history to the stagnant lid model that exists today. A stagnant lid means its surface has only a single plate with minimal amounts of movement to release gases into the atmosphere.
“We have so far thought about a tectonic state in terms of a binary: it’s either true or it’s false, and it’s either true or false for the duration of the planet,” Alexander Evans, an assistant professor of Earth, environmental and planetary sciences at Brown University and co-author of the study explained.
The new findings, he said, suggest that planets may transition in and out of different tectonic states. “This also means we might have planets that transition in and out of habitability rather than just being continuously habitable,” he highlighted.
The researchers are hopeful that the National Aeronautics and Space Administration’s upcoming mission to Venus, DAVINCI, may provide some clues and confirm the study’s findings. They also plan to understand how Venus lost its plate tectonics.
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