Active volcanoes on Venus

For the first time, direct geological evidence of recent volcanic activity has been observed on the surface of Venus.

The authors of the finding have made the discovery after examining and analyzing archival images of the surface of Venus that were captured by radar by the Magellan space probe (Magellans) more than 30 years ago, in the 1990s. The images have revealed a volcanic vent that changed shape and increased considerably in size in less than a year.

Studying active volcanoes helps us understand how a planet’s interior can shape its crust, drive its geological evolution, and affect its habitability. One of NASA’s new missions to Venus will have just that as its primary goal. VERITAS (Venus Emissivity, Radio science, InSAR, Topography, And Spectroscopy) will be launched in a decade. The orbiter will remotely study the surface of Venus and its deep interior, right down to the core, to try to figure out how a rocky planet the same size as Earth and only slightly closer to the Sun took a very different path than our own. world, becoming a planet covered in volcanic plains and deformed terrain hidden under a thick, torrid atmosphere.

Robert Herrick, from the University of Alaska at Fairbanks in the United States, and who is also a member of the VERITAS science team, decided to look for recent volcanic activity in the data collected by Magellan, although he confesses that he did not think he would find anything. However, after some 200 hours of manually comparing images of each area taken by Magellan at different times, he found that two images of the same area taken eight months apart showed telltale geological changes caused by an eruption.

This global map of the surface of Venus is computer generated from data from NASA’s Magellan and Pioneer Venus Orbiter missions. Maat Mons, the volcano that has shown signs of a recent eruption, lies within the black square near the planet’s equator. (Image: NASA JPL/Caltech)

The geological changes discovered by Herrick occurred in Atla Regio, a vast mountainous region near Venus’s equator that is home to two of the planet’s largest volcanoes, Ozza Mons and Maat Mons. It has long been believed that the region it was volcanically active, but there was no direct evidence of recent activity. By scrutinizing the images captured by Magellan, Herrick identified a volcanic vent, associated with Maat Mons, which changed significantly between February and October 1991.

In the February image, the chimney appeared almost circular, covering an area of ​​less than 2.2 square kilometers. It had steep inner sides and showed signs of lava draining down its outer slopes, factors indicating activity. In radar images taken eight months later, the same chimney had doubled in size and deformed. It also seemed to be filled to the brim with a lake of lava.

But because the two observations were made from opposite viewing angles, they had different perspectives, making it difficult to compare. The low resolution of the radar images, captured using technology more than thirty years old, made the job even more difficult.

Herrick then turned to NASA’s Scott Hensley, a member of the VERITAS mission science team and a specialist in analyzing radar data such as those from Magellan. The two researchers created computer models of the chimney in various configurations to test different scenarios of geological phenomena, such as landslides. From those models, they concluded that only an eruption, which occurred on the surface of Venus during the Magellan mission, could have caused the change.

The study is titled “Surface changes observed on a Venusian volcano during the Magellan mission”. And it has been published in the academic journal Science. (Fountain: NCYT by Amazings)