(CNN) Recently, when scientists looked more closely at archival images of the surface of Venus, they discovered something new: evidence of volcanic activity on Earth’s “twin.”
NASA’s Magellan spacecraft captured the images in the early 1990s as it orbited our nearest planetary neighbor, which is similar in size and composition to Earth.
A new analysis of a region near the Venusian equator from the orbiter’s perspective reveals a volcanic vent that changed shape and grew sharply in size over the course of eight months.
The images of the vent represent the first direct geological evidence of recent volcanic activity on the surface of Venus, according to the researchers. A study detailing the findings was published Wednesday in the journal Science and at the 54th Lunar and Planetary Science Conference at The Woodlands, Texas.
The Magellan mission was the first to image the entire surface of Venus before the spacecraft intentionally plunged into the planet’s hot, toxic atmosphere in 1994 to collect one final dataset. But within a decade, a fleet of new missions will embark on Venus, including VERITAS, the Venus Emissivity, Radio Science, InSAR, Topography, and Spectroscopy mission.
Active volcanic landscape
The orbiter will use its instruments to unravel the mysteries of why an Earth-like planet was covered by volcanic plains and crowned by an inhospitable atmosphere.
“NASA’s selection for the VERITAS mission inspired me to look for recent volcanic activity in Magellanic data,” said study lead author Robert Herrick, research professor at the University of Alaska Fairbanks and member of the VERITAS science team. in a statement.
“I didn’t really expect to be successful, but after about 200 hours of manually comparing images from different Magellanic orbits, I saw two images of the same region taken eight months apart, showing telltale geological changes caused by an eruption were caused.”
Herrick spotted the changes in images of Atla Regio, a vast highland region that is home to two of Venus’ largest volcanoes, called Ozza Mons and Maat Mons. Both resemble Earth’s largest volcanoes, but because they have lower slopes, the two Venusian volcanoes are more spread out, Herrick said.
He noticed that a volcanic vent on the north side of a volcanic cone that was part of Maat Mons changed between February and October 1991.
Magellan’s February image of the vent showed a circular vent extending less than 2.2 square kilometers, with steep interior sides and areas of vented lava on the slopes.
Eight months later, the spacecraft captured another image, showing an entirely different vent that appeared misshapen, had almost doubled in size, and was almost brimming with a lava lake.
Although the differences sound obvious, both images were captured from opposite angles and perspectives, and at much lower resolution than the images captured by the cameras found on spacecraft today.
3D Mapping of Venus
Herrick worked with Scott Hensley, project scientist for VERITAS at NASA’s Jet Propulsion Laboratory in Pasadena, California, to create computer models of the vent to determine what might have caused the changes.
“Only a few of the simulations matched the images, and the most likely scenario is that volcanic activity took place on the surface of Venus during Magellan’s mission,” Hensley said. “Although this is only one data point for an entire planet, it confirms that there is modern geological activity.”
Researchers believe the lava flow Magellan experienced in 1991 was similar to that released by the 2018 Kilauea eruption in Hawaii.
“It was a needle-in-a-haystack search with no guarantee that the needle existed,” Herrick said. “Finding a change that could be positively verified as real was absolutely surprising. We were pretty sure Venus was volcanically active, but we didn’t know if eruptions occur every few months, years, once every 10,000 years, or longer. All options could have matched the existing data. Unless we were incredibly lucky, we now know that the frequency is every few months or so, similar to the family of Earth’s large intraplate basaltic volcanoes such as Hawaii, the Galapagos Islands, the Canary Islands, etc.
While it’s possible that a tremor triggered the collapse of the volcanic vent’s walls, researchers believe such activity would also have caused a volcanic eruption.
Volcanoes act like windows into a planet’s interior, allowing scientists to understand more about what factors affect its ability to be a habitable world. Missions like VERITAS will help scientists better understand Venus, just as Magellan did decades ago.
The new mission will be equipped with radar to create 3D global maps of Venus and capture details about its surface composition, gravitational field and events in the planet’s past.
“Venus is an enigmatic world, and Magellan has shown so many possibilities,” said Jennifer Whitten, VERITAS associate associate principal investigator and assistant professor of earth and environmental sciences at Tulane University in New Orleans, in a statement. “Now that we are very confident that the planet experienced a volcanic eruption just 30 years ago, this is a small preview of the incredible discoveries VERITAS will make.”