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NASA spots first evidence of an active volcano on Venus – in a big pile of CD-ROMs

Disc-trawling expedition of 30-year-old data turns up trumps

Astronomers have uncovered the first evidence of an active volcano on Venus, using computer images captured more than 30 years ago by a NASA spacecraft.

Launched in May 1989, the Magellan probe became the first of its kind to image almost the entire surface of Venus (like, 98 percent) using radar. The spacecraft no longer exists – it was crashed into the planet in 1994. About 1,200 gigabits of data – more than all previous NASA planetary missions combined – was beamed back before the smash, and that information is proving useful to this day. 

Researchers working on NASA's VERITAS* spacecraft, expected to launch within a decade to study Venus, decided to dig through a mountain of CD-ROMs containing archives of data taken from Magellan to study the planet's volcanic activity.

"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," said Robert Herrick, a geophysics professor of at the University of Alaska Fairbanks and member of the VERITAS science team. 

The photos were snapped at the Atla Regio – an area near Venus's equator that is home to two of the largest volcanoes: Ozza Mons and Maat Mons, measuring hundreds of kilometers in diameter. Images taken between February and October 1991 show Maat Mons was active during that time.

The older image featured what looked like a vent with lava bubbling down its sides in a region measuring less than a square mile (2.6 square kilometers). The later one showed the same vent had changed shape, doubled in size, and was brimming with lava. The images were snapped at different angles, however, making it difficult for astronomers to compare directly.


We may get a proper look in a few years – A 3D computer-generated image of Maat Mons volcano on Venus. Image credit: NASA JPL-Caltech (Source)

Herrick and his colleagues extracted data from Magellan's images to model the vent's activity, adjusting the images and making them appear as if they were taken from the same viewpoint directly overhead. More details on the research can be found in a paper published in Science on Wednesday. 

"Only a couple of the simulations matched the imagery, and the most likely scenario is that volcanic activity occurred on Venus's surface during Magellan's mission," said Scott Hensley, the project scientist for VERITAS and an expert in studying radar data. Other potential scenarios modeled – like landslides, for example – did not match the end images.

"While this is just one data point for an entire planet, it confirms there is modern geological activity," he said. 

The VERITAS craft should help astronomers help clarify what's going on down on Venus by capturing even more detailed 3D maps of the Venusian surface using more advanced radar technology. It will also carry instruments capable of measuring the planet's gravitational field to analyze its interior, which will provide insight into its geological processes. 

"Venus is an enigmatic world, and Magellan teased so many possibilities," said Jennifer Whitten, associate deputy principal investigator of VERITAS at Tulane University in New Orleans. "Now that we're very sure the planet experienced a volcanic eruption only 30 years ago, this is a small preview for the incredible discoveries VERITAS will make."

Astronomers have long been fascinated by the second planet in the Solar System. Its size and composition are similar to Earth and it likely formed at the same time. But its environment is hot and hazy due to the greenhouse effect, whereby its dense clouds trap heat. Scientists believe Venus is an example of how Earth could change if its climate continues to warm. 

ESA, Russia's Roscosmos, and India's Space Research Organization are also planning missions to Venus. The first-ever private mission to the planet from US startup Rocket Lab is expected to launch in May this year. ®

* It stands for Venus Emissivity, Radio science, InSAR, Topography, And Spectroscopy, which is incredibly contrived and awkward – but NASA employs some of the greatest minds to come up with cool acronyms.

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