Analysis of Magellan data shows apparent volcanic activity on Venus

Analysis of archived high-resolution radar mapping data captured by NASA’s Magellan probe more than 30 years ago shows what may be the first signs of active volcanism on cloud-shrouded Venus. The before-and-after images show what appears to be a volcanic vent increasing in size in less than a year.

“It is really only in the last decade or so that the Magellan data has been available at full resolution, mosaicked and easily manipulable by an investigator with a typical personal workstation,” said Robert Herrick, a University of Alaska Fairbanks Geophysical Institute research professor.

“We can now say that Venus is presently volcanically active in the sense that there are at least a few eruptions per year.”

Analysis of Magellan radar imagery captured in 1991 shows what appears to be the result of an eruption from a volcanic vent on Maat Mons, a large volcano near the equator of Venus. The before-and-after images at right show apparent lava flows. Image: Robert Herrick/UAF

With upcoming missions now on the drawing board, “we can expect (to) observe new volcanic flows that have occurred since the Magellan mission ended three decades ago, and we should see some activity occurring while the two upcoming orbital missions are collecting images.”

He was referring to NASA’s Venus Emissivity, Radio science, InSAR, Topography And Spectroscopy probe – VERITAS – and ESA’s EnVision spacecraft, both equipped with high-tech synthetic aperture radar to map the surface despite the planet’s perpetual cloud cover.

“NASA’s selection of the VERITAS mission inspired me to look for recent volcanic activity in Magellan data,” said Herrick, a member of the VERITAS science team. “I didn’t really expect to be successful, but after about 200 hours of manually comparing the images of different Magellan orbits, I saw two images of the same region taken eight months apart exhibiting telltale geological changes caused by an eruption.”

A computer-generated view of Maat Mons, released in 1992, shows the huge volcano from a viewpoint 634 kilometres (393 miles) away. Image: NASA/JPL

The changes he spotted were in Atla Regio, a vast highlands region near Venus’ equator where two of the planet’s largest volcanoes are located – Ozza Mons and Maat Mons. In images captured in February 1991, a single roughly circular vent covering an area of about 2.2 square kilometres was seen near Maat Mons. Eight months later, the vent had doubled in size and had become misshapen.

Herrick and Scott Hensley, the VERITAS project scientist at NASA’s Jet Propulsion Laboratory, concluded the changes could only be the the result of an eruption.

“Only a couple of the simulations matched the imagery, and the most likely scenario is that volcanic activity occurred on Venus’ surface during Magellan’s mission,” said Hensley. “While this is just one data point for an entire planet, it confirms there is modern geological activity.”

The lava flow generated in the eruption was comparable to the 2018 eruption of Mount Kilauea in Hawaii.