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Vent on Venus is clearest sign yet the planet is volcanically active

After painstakingly combing through radar images collected by NASA’s Magellan probe in the 1990s, researchers have found a vent that grew larger – evidence of current volcanic activity

By Alex Wilkins

15 March 2023 , updated 15 March 2023

Venus - 3D Perspective View of Maat Mons Photojournal: PIA00106 Source: NASA/JPL Published: May 10, 2004 Maat Mons is displayed in this computer generated three-dimensional perspective of the surface of Venus. The viewpoint is located 634 kilometers (393 miles) north of Maat Mons at an elevation of 3 kilometers (2 miles) above the terrain. Lava flows extend for hundreds of kilometers across the fractured plains shown in the foreground, to the base of Maat Mons. The view is to the south with the volcano Maat Mons appearing at the center of the image on the horizon and rising to almost 5 kilometers (3 miles) above the surrounding terrain. Maat Mons is located at approximately 0.9 degrees north latitude, 194.5 degrees east longitude with a peak that ascends to 8 kilometers (5 miles) above the mean surface. Maat Mons is named for an Egyptian Goddess of truth and justice. Magellan synthetic aperture radar data is combined with radar altimetry to develop a three-dimensional map of the surface. The vertical scale in this perspective has been exaggerated 10 times. Rays cast in a computer intersect the surface to crate a three-dimensional perspective view. Simulated color and a digital elevation map developed by the U.S. Geological Survey are used to enhance small-scale structure. The simulated hues are based on color images recorded by the Soviet Venera 13 and 14 spacecraft. The image was produced by the Solar System Visualization project and the Magellan Science team at the JPL Multimission Image Processing Laboratory and is a single frame from a video released at the April 22, 1992 news conference.

The Maat Mons volcano system on the surface of Venus may be active today

NASA/JPL

A volcanic vent on Venus that changed shape over a period of eight months is the first direct evidence that our neighbouring planet is volcanically active.

Venus has many prominent volcanic features, such as vents and the dry beds of lava lakes, but it was unclear whether these were remnants of a distant volcanic past or signs of current activity.

Between 1990 and 1994, NASA’s Magellan satellite used radar to map Venus’s surface in detail, including its volcanic features. Until recently, however, computers were ill-equipped to properly analyse the vast amount of data it generated.

The way in which Magellan mapped Venus’s surface, taking photos every eight months at different viewing angles, also made it impossible to automatically search for changes in surface features. The only way to identify differences was to look through the images by eye.

“The daunting aspect of this is it’s a needle-in-a-haystack search, where there’s no guarantee that the needle exists,” says Robert Herrick at the University of Alaska Fairbanks, who, along with Scott Hensley at NASA’s Jet Propulsion Laboratory in California, presented the findings at the Lunar and Planetary Science Conference in Houston, Texas, on 15 March.

By combing through areas of Venus’s surface in which they thought volcanic activity was more likely, the pair found the vent, which is in the Maat Mons volcano system, home to the planet’s highest volcano.

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Between February and October 1991, the vent changed from a circular, 2-square-kilometre hole to a more shallow, irregular hole with an area almost twice as big. In the later images, there were also features downhill from the vent that looked like active lava flows, but the images weren’t clear enough to fully make them out. “A reasonable interpretation is that a lava lake formed over those eight months, and that volcanism occurred downhill,” says Herrick.

While the finding validates many predictions and hypotheses about active volcanism on Venus, it tells us little about the frequency of volcanic eruptions on the planet because it is the only sample we have – but the fact that we saw it at all could tell us something.

“There’s the possibility that we observed the only thing that’s happened on Venus in the last 1000 years and got incredibly lucky, but the odds are that if we saw something change over a short, eight-month period, then at least volcanic eruptions occur on Venus at a similar sort of level to the intraplate volcanism on Earth, in the every-few-months time frame,” says Herrick.

“We know Venus must be active, but demonstrating it from Magellan data has, until now, proven elusive,” says Philippa Mason at Imperial College London.

Confirming that Venus is volcanically active is especially useful given upcoming missions to Venus, says Mason, such as the European Space Agency’s EnVision and NASA’s VERITAS satellites. These missions will use radar – like Magellan did, but in a more advanced form – to map the planet’s surface and interior, as well as spectroscopy to analyse gases in its atmosphere. These methods will teach us more about the extent and nature of Venus’s volcanism.

Journal reference:

Science DOI: 10.1126/science.abm7735

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