Volcanoes on Venus? Finding “flashy” evidence of modern activity

Scientists have found some of the strongest evidence that volcanic activity exists on Venus. Since the planet is a close neighbor of Earth and originally had water on its surface, a big question has been why its landscape is hellish while Earth’s is habitable. Learning more about its volcanic activity could help explain its evolution – and that of Earth.

Scientists know that Venus is covered in volcanoes, but whether or not any of them are still active has long been debated. Now researchers have discovered that at least one of them is likely by examining radar images of the planet’s surface taken by NASA’s Magellan spacecraft between 1990 and 1992. The planet’s largest volcanoes changed shape between two images, spaced eight Months ago, suggesting an eruption or magma flow beneath the vent. The scientists reported their findings in Science1 on March 15 and presented them the same day at the Lunar and Planetary Science Conference in Woodlands, Texas.

This is a “remarkable find,” says Darby Dyar, an astronomer at Mount Holyoke University in South Hadley, Massachusetts. It brings the space research community a step closer to understanding how Venus works, adds Dyar, who is also an associate principal investigator on the VERITAS mission to Venus, overseen by NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California. and aims to map the planet’s surface sometime after 2030. “The whole issue of whether there is active volcanism on the surface of Venus suffers from a lack of data,” she adds.

A hell planet

Gathering evidence that the planet is volcanically active has not been easy. Venus’ dense atmosphere – 100 times heavier than Earth’s – and high temperatures – 450°C – make it difficult for rovers and other probes to explore the surface. So far, the most reliable data scientists have collected comes from the Magellan spacecraft.

Robert Herrick, a geophysicist at the University of Alaska Fairbanks, and Scott Hensley, a radar scientist at JPL who is also part of the VERITAS team, analyzed full-resolution radar images taken by Magellan of areas of suspected volcanic activity.

The challenge was that Magellan imaged the planet in three different cycles during its 24-month mission. During each cycle, it aimed its radar at a different angle at the surface of Venus. In order for the scientists to look for changes on the surface over time, they had to overlay the images at different angles and find overlaps in the terrain to align them.

Herrick likens the problem to flying through the Grand Canyon in Arizona from multiple directions and then trying to map its surface while looking at the opposite walls of the canyon. “Trying to find the same things in these images becomes a little more difficult,” he says.

The low resolution of the Magellan images added another layer of complexity. “You’re looking at the surface where a soccer field is just a single pixel,” he adds.

This worries Scott King, a geophysicist at Virginia Tech University in Blacksburg who studies Venus. He wonders if the images are powerful enough to convince skeptics that Venus is volcanically active. “The proof is in the eye of the beholder,” he says.

Herrick and Hensley acknowledge this limitation in their data. But they also say they’re not aware of a similar event on Earth that could cause the changes they’re observing without volcanic activity, although they can’t rule out the possibility that something else might have been responsible.

King doesn’t find it hard to believe that the planet has volcanic activity. However, he hopes upcoming missions to Venus, including VERITAS, will provide the data needed to convince everyone.

An overlooked planet

However, VERITAS has been delayed – so King may be waiting longer than originally thought. NASA had planned to launch the mission in 2028, but the agency has had to reallocate funds to address the delay of Psyche, another mission that will study a metal-rich asteroid orbiting the sun between Mars and Jupiter. NASA currently has no funding planned for VERITAS in the coming years, and if it does restore funding, the mission would not launch until 2031 at the earliest.

Launching VERITAS after 2030 could cause problems for other missions, Dyar says. Ideally, the topographical data collected by VERITAS would have provided NASA’s DAVINCI and the European Space Agency’s EnVision with information that would help them better target areas they plan to explore. DAVINCI, due to launch in 2029, aims to launch a probe into Venus’ atmosphere, and EnVision, due to launch in the early 2030s, is set to capture high-resolution radar images of the planet’s surface.

Studying Venus could not only help researchers understand more about how Earth works, but also learn more about exoplanets outside the solar system. “We’re discovering hundreds, thousands of exoplanets,” says Dyar. And many of these appear to be Venus-like, she adds.

Many space missions have recently targeted Mars, although overall Venus is much more Earth-like than the red planet. Herrick hopes the new findings will motivate people to keep their eyes on Venus and bring VERITAS to market in a timely manner. “Venus really is Earth’s sister,” he says.

This article is reproduced with permission and was first published on March 15, 2023.