How Venus’ Volcanoes Protect Earth

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It’s possible that Venus’s transformation by volcanism spared Earth.

Venus may have become the oppressive, sulfuric, hellish planet it is today due to massive worldwide volcanism that coated 80% of Venus’ surface in lava. Venus was formerly a moist and gentle globe.

Under the thick clouds of carbon dioxide mixed with corrosive sulfuric acid, Venus has a scorching surface temperature of 867 degrees Fahrenheit (464 degrees Celsius), hot enough to melt lead, and a crushing pressure of 90 atmospheres. Venus, sometimes referred to as the “evil twin” of Earth, suffers from a runaway greenhouse effect, which is undoubtedly exacerbated by the fact that Venus is around 25 million miles (40 million kilometers) closer to the sun than Earth and hence experiences more heat.

Despite this, there is mounting evidence that Venus wasn’t always like this and may have once been a temperate world similar to Earth — possibly more recently, geologically speaking.

The majority of the research leading to the creation of this new image of Venus was conducted by Michael Way of NASA’s Goddard Space Flight Center in Maryland. He and his team make the case in their most recent paper that Venus’ volcanism, which is known to be a powerful greenhouse gas, may have ultimately been what caused the planet to pass the tipping point.

Radar mapping of Venus’ surface in the 1990s by NASA’s Magellan spacecraft revealed that volcanic basalt rock covered much of the planet’s surface, which is normally hidden by the planet’s thick atmosphere. The immense volcanism that produced these “large igneous provinces” over tens of thousands, if not hundreds of thousands of years had place at some point within the last billion years.

In particular, a series of these lava-filled eruptions, maybe occurring over the course of a million years, could have filled Venus’ atmosphere with so much carbon dioxide that the planet’s climate would have been unable to handle it. Since water vapor is also a greenhouse gas, any oceans would have evaporated, moistening the air and hastening the greenhouse effect. The water would have eventually been lost to space, but the carbon dioxide and hostile environment would have persisted.

In a statement, Way said that by looking at Earth’s own history, “we should be able to narrow down how frequently the events which created these fields occurred.”

Given how frequently large igneous provinces are formed by massive volcanic eruptions on Earth, it is likely that Venus experienced a number of similar eruptions within a million years. These events might have left Venus permanently scarred.

Even Earth has seen some narrow escapes. Over the past half-billion years, a number of catastrophic extinction events on Earth have been linked to so-called “super-volcanoes.” For instance, some have suggested that super-volcanism in what is now Russia and Siberia, as well as a separate super-volcanic eruption in Australia, were responsible for the Late Devonian age mass extinction that occurred 370 million years ago. The creation of the Central Atlantic Magmatic Province, the largest of Earth’s great igneous provinces, 200 million years ago is commonly credited with causing the Triassic-Jurassic mass extinction. Even the demise of the dinosaurs 65 million years ago may have resulted from a combination of super-volcanism in the Deccan Traps, a sizable igneous province in India, and an asteroid strike.

Similar volcanic eruptions were much more frequent on Venus for unknown reasons, which sparked a runaway greenhouse effect that changed the planet. While this was happening, Earth was able to avoid going in the same direction as Venus thanks to the carbon-silicate cycle, which has been able to exchange carbon dioxide and other greenhouse gases between the mantle and the atmosphere over millions of years.

Two upcoming NASA missions will try to provide some of these answers. VERITAS, the Venus Emissivity, Radio Science, InSAR, Topography and Spectroscopy mission will launch in the early 2030s. DAVINCI, the Deep Atmosphere Venus Investigation of Noble Gases, Chemistry and Imaging mission, will launch later this decade. While China has suggested a potential mission named VOICE, the Venus Volcano Imaging and Climate Explorer, that if launched would reach Venus in 2027 to investigate the planet’s atmosphere and geology, the European Space Agency’s EnVision mission also plans to launch sometime in the 2030s.

DAVINCI’s main objective, according to Way, is to pinpoint the history of water on Venus and when it may have vanished in order to shed more light on the planet’s climate history.

The results were released earlier this year in the Planetary Science Journal.


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