NASA scientists have seen direct geological evidence of active volcanism on Venus for the first time ever.
The recent volcanic activity was discovered after examining radar images of Earth's twin taken more than 30 years ago by NASA's Magellan mission.
The images revealed a volcanic vent changing shape and increasing in size over the period of less than a year.
"NASA’s selection of the VERITAS mission inspired me to look for recent volcanic activity in Magellan data," University of Alaska Fairbanks research professor Robert Herrick, who led the search of the archival data, said in a statement. "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."
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The VERITAS (Venus Emissivity, Radio science, InSAR, Topography And Spectroscopy) mission will launch within a decade, sending an orbiter to study Venus from surface to core.
The geological changes found occurred in the Alta Regio, a highland region near the planet's equator which is home to the Ozza Mons and Maat Mons volcanoes.
While the region was long believed to be volcanically active, there was no direct evidence of the recent activity.
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The search and its results were published in a study in the journal Science.
While looking at Magellan radar images, Herrick identified a volcanic vent associated with Maat Mons that changed significantly between February and October 1991.
In the February image, the vent appeared nearly circular and showed signs of drained lava down its exterior slopes. Eight months later, the same vent had become misshapen and was filled to the rim with a lava lake. After teaming up with the Jet Propulsion Laboratory's Scott Hensley – who is the project scientist for VERITAS – the researchers created computer models, concluding that only an eruption could have been responsible for the change.
"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."