Volcanism on Venus

        There are more than 85,000 volcanoes on Venus , our closest planetary neighbor in the Solar System, has long remained shrouded in a cloud of mystery—literally. The planet sits in a thick, dense atmosphere of carbon dioxide that prevents our direct view of its surface.

Recently, however, planetary scientists did new discoveries about the geography of Venus, which suggest that the planet has at least 85,000 volcanoes on its surface (and potentially even more smaller volcanoes). The research brings us closer to understanding the evolution and geological structure of the planet.

Read more: The case for life on Venus and the privately funded mission to find it

Magellan Orbiter

In the 1990s, NASA launched the Magellan Orbiter in an attempt to image the surface of Venus. To date, the mission remains one of the most successful: before plunging into Venus’ atmosphere, the orbiter was able to break through the opaque cloud layer and image the surface with Synthetic Aperture Radar (SAR).

“The Magellan radar worked by beaming pulses of energy (in this case, microwave energy) to the surface of Venus,” says graduate student Becca Hahn, “and then receiving the echoes, or reflected pulses, which essentially created a radar ‘image’ of the surface.”

Khan co-authored the previously mentioned research which analyzes the surface data of the Magellan orbiter in the most detail to date. She and her colleague Paul Brain of the University of Washington used advanced mapping software to analyze data collected by Magellan from the surface of Venus more than 30 years ago. .

“The resolution of the Magellan synthetic aperture radar data is quite coarse, and we probably missed many smaller volcanoes that were below the resolution limit,” Hahn says. “Future planned missions to Venus, such as NASA’s Veritas and [the European Space Agency’s] EnVision, will collect higher-resolution radar images of the planet, so we’ll be able to identify smaller volcanoes.

Mapping Venus

Planetary scientists first became aware of extensive volcanism on Venus when the Magellan data became publicly available in the 1990s.

At the time, scientists had to outline volcano footprints by hand, an extremely tedious and time-consuming task. But the new software has given scientists a much more detailed picture of the role that volcanism plays in shaping the surface of Venus.

Hahn explains that understanding the sizes, shapes and distribution of volcanoes can provide clues to what might be going on below the surface. For example, if researchers identify a cluster of small volcanoes but not a proximal large volcano, this could mean that the rate of magma supply is relatively low and could supply many small volcanoes—but no large one.

Also, although Venus is currently understood not to have Earth-like plate tectonics, the data provided by Magellan show tectonic structure such as folds, faults, rift zones, and mountains all over the planet.

“There are some recent studies [conducted by Byrne] suggesting that Venus may have ‘block tectonics,’ where chunks of blocks of the Earth’s crust have been bumped together like broken pieces of pack ice,” Hahn says. “Once again, future missions will help us better understand these processes.”

Active volcanoes on Venus

Recently, Magellan data has also been used to identify a volcano that appears to be active. By looking for changes in the landscape of areas the orbiter has passed through multiple times, researchers have been able to determine that Venus is indeed still geologically active.

According to Hahn, it’s exciting to think that there may be many more active volcanoes on the surface—and that she and Byrne may have actually identified them in their recent data set.

“I hope there are additional active volcanoes on the planet,” she says, “but at this point we don’t know how many more are active.” Only future research will tell.

Read more: First evidence of a recently active volcano on Mars

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