Radar images taken more than 30 years ago have just revealed the most conclusive evidence of an erupting volcano on Venus, Earth’s twin planet that, for unknown reasons, became a hellish world whose surface touches 500 degrees, enough to melt lead.
In 1991, the probe Magellan NASA – named after the navigator sent by Spain in the 16th century on the expedition that first circumnavigated the world – mapped the planet’s surface using radar. Radio signals pierced the thick clouds and revealed the orography in three dimensions. Mankind gazed upon a planet riddled with volcanoes, though whether they were active or geological relics from the remote past was impossible to tell.
Magellan easily broke the record for information sent to Earth from another planet: 1,200 gigabytes, more than all previous missions combined. Today it seems like a derisory amount, but the truth is that some of the radar images were so heavy that for a long time it was not possible to analyze them in detail with conventional computers, he explains to this newspaper. scott hensley, a researcher at NASA’s Jet Propulsion Laboratory. A few years ago, this physicist began to compare the images of Magellan taken in two successive passes over the same place in February and October 1991. The results, now published in the journal Sciencepodium of world science, provide the strongest proof to date that Earth is not the only planet in the solar system where there are active volcanoes.
In the images of the first pass, the probe portrayed a volcanic fissure of about two square kilometers and a depth of 175 meters, like a 58-story skyscraper. When the spacecraft passed through it again eight months later, the crack had doubled in size and seemed to have filled to the brim with a material that scientists think can only be lava. The molten rock would have covered an area of almost 70 square meters, more or less double that of the eruption of the Kilauea volcano, in Hawaii (United States), in 2018, the study highlights.
Although it is not “100% certain” that it is a volcanic eruption, since the observations are almost at the limit of the resolution of the radar, the volcano is “the most plausible explanation”, says Hensley. The new eruption is on the slopes of Maat Mons, the highest volcano on Venus, which was thought to be extinct.
robert herrick is a geophysicist at the University of Alaska at Fairbanks and a co-author of the study. “Until now there was indirect evidence of volcanism on Venus,” he explains. “There are indications of chemical reactions that point to eruptions and other geological data of activity, but it could not be known if they happened thousands of years ago or are happening right now. Our work shows a new volcanic structure that formed in eight months of 1991 and is the most conclusive proof of an eruption on the planet”, he highlights.
With these tests, Venus would become the second planet in the solar system with active volcanism next to Earth. To these two is added Io, Jupiter’s moon, undoubtedly the most active body in the entire solar system, where there are hundreds of volcanoes that spew lava fountains several kilometers high.
In December, the discovery on Mars of an active volcanic area as large as all of Europe and which could erupt at any time was announced. Finding volcanoes is always interesting because, at least on Earth, these bodies create habitable environments for living things.
The possibility of life on Venus is remote, but not impossible. In September 2020, scientists from Europe and the US announced the discovery of phosphine, a chemical compound in the atmosphere that could be the first evidence of life found on the planet. Since then, various teams have tried unsuccessfully to replicate that detection, and the possibility of the planet being habitable has been deflated.
Iván López, a planetary geologist from the Rey Juan Carlos University in Madrid, is an expert in Venusian geology and participates in the ExoMars mission of the European Space Agency. “Venus and Earth were born twins,” he explains. “They have practically the same size and the same composition. Venus may even have water. But something happened that triggered a brutal greenhouse effect. All the experts on Venus think that there are active volcanoes, but the truth is that there has been no conclusive evidence so far. We do know that this planet does not have plate tectonics like Earth. So understanding how plateless volcanism is possible can help us better understand an alternative mechanism of volcanism and even detail how tectonics originated on Earth, which is essential for it to be habitable,” he explains.
In 2031, the United States and Europe are launching two new missions to Venus to study both its thick atmosphere for life and its scorching, orange surface. Hensley and Herrick are collaborating with both missions, Veritas and EnVision, respectively, developing the new radars that will re-map the planet for volcanic activity.
On April 27, 1521, the sailor Ferdinand Magellan died in combat against the natives of the island of Mactan (Philippines). The Gipuzkoan Juan Sebastián Elcano took command of the expedition until he took it back to Spain after having completed the first circumnavigation of the Earth. The Magellan space probe was also killed, somehow, in combat. In October 1994, NASA engineers made it plunge into the clouds of Venus until it disintegrated. However, their data may hide many more surprises, says Herrick: “The probe covered at least twice up to 40% of the surface of Venus, and so far we have only analyzed 1.5% in detail.”
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