Volcanoes were erupting on Venus in the 1990s

I start talking about Venus and immediately my mind goes to those images of the Venera space probes that visited Venus in the 1970s. They revealed a world that had been scarred by millennia of volcanic activity but, as far as we knew, those volcanoes were dormant. That is, until now. Magellan has been mapping the surface of Venus and between 1990 and 1992 he had mapped 98% of the surface. The researchers compared two scans of the same area and found that there were new flows of molten rock filling a vent crater. There was active volcanism on Venus.

Venus is the second planet from the Sun and is similar in size to Earth, although the similarities end there. It has a thick atmosphere that is toxic to life as we know it, there is sulfuric acid rain high in the atmosphere, and a surface temperature of almost 500 degrees. When the Venera probes visited, they measured an atmospheric pressure of around 90 times that of the Earth’s surface. Combined with other hostile properties of the atmosphere, a human visitor would not survive for long.

Venus

Venus’ dense atmosphere is largely the result of volcanic activity. Over the millennia, there have been extensive volcanic eruptions that pumped carbon dioxide into the atmosphere. The lack of water masses on Venus meant that carbon dioxide accumulated in the atmosphere was not absorbed. In addition to this, the lack of a magnetic field meant that the solar wind (pressure from the Sun) chased away the lighter elements leaving behind the thick, carbon dioxide-rich atmosphere we see today. But the volcanoes that caused the atmospheric changes are thought to have long gone extinct.

It’s not just the Venera probes that have been exploring Venus. In 1980, NASA launched the Magellan spacecraft to map the surface of the hottest planet in the Solar System. Upon arrival, it was placed into a polar orbit and used radar to penetrate the thick clouds. In 2023, a study of some of Magellan’s synthetic aperture radar images showed changes in a vent near the summit of Maat Mons. It was the first direct evidence of an eruption on the surface of Venus and changes in lava flows. .

The surface of Venus captured by a Soviet Venera probe. Credit: Russian Academy of Sciences / Ted Stryk

More data from synthetic aperture radar were studied in the latest study published in Nature Astronomy. The team focused on Sif Mons and Niobe Planitia and on data that had been collected from both areas in 1990 and again in 1992. The data revealed stronger radar returns in the latter data set that suggested new rock formations of volcanic activity. . The team considered that it could have been caused by other phenomena such as sand dunes or atmospheric effects, but the altimeter data confirmed the presence of new solidified lava.

The team was able to use lava flows on Earth as a comparison to help understand the new flows on Venus. They estimated that the new flows are between 3 and 20 meters deep. However, they could go a step further and estimated that the Sif Mons eruption produced about 30 square kilometers of rock that would be enough to fill more than 36,000 swimming pools. The Niobe Planitia eruption produced even more with an estimated 45 square kilometers of rock.

The study of volcanic activity on Venus helps to understand not only the geological processes, but also the structure of the interior. This can help inform the probability of habitability for future explorers. None of this would have been possible without the recent volcanic activity that helped us further investigate the secrets of Venus.

Source: Ongoing volcanic activity on Venus discovered with NASA Magellan data