(CNN) When scientists recently took a closer look at archival images of the surface of Venus, they discovered something new: evidence of volcanic activity on Earth’s “twin.”
The NASA 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 the orbiter’s perspective of a region near Venus’ equator reveals a volcanic vent that changed shape and greatly increased in size over the course of eight months.
The images of the opening 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 was presented at the 54th Lunar and Planetary Science Conference in The Woodlands, Texas.
The Magellan mission became 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 a final set of data. But a fleet of new missions will head for Venus within a decade, including the VERITAS, Venus Emissivity, Radio science, InSAR, Topography, And Spectroscopy mission.
Active volcanic landscape
The orbiter will use its instruments to uncover the secrets of why an Earth-sized planet was covered in volcanic plains and topped with an inhospitable atmosphere.
“NASA’s selection of the VERITAS mission inspired me to look for recent volcanic activity in the Magellan data,” lead study author Robert Herrick, a research professor at the University of Alaska Fairbanks and a member of the VERITAS science team, 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 that showed clear geological changes caused by an eruption.”
Herrick spotted the changes in the images of the Atla Regio, a large highland area home to two of Venus’ largest volcanoes, called Ozza Mons and Maat Mons. Both are similar to Earth’s largest volcanoes, but because they have lower slopes, the two Venusian volcanoes are more spread out, Herrick said.
He noted that a volcanic vent on the north side of a dome volcano that was part of Maat Mons changed between February and October 1991.
Magellan’s image of the vent from February showed a circular vent spanning less than 1 square kilometer (2.2 sq mi) with steep interior sides and areas of drained lava on the slopes.
Eight months later, the spacecraft captured another image that showed a drastically different vent that appeared misshapen, had nearly doubled in size, and was filled almost to the brim with a lake of lava.
Although the differences sound obvious, both images were taken from opposite angles and perspectives and at much lower resolution than images taken by the cameras included 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 occurred on the surface of Venus during the Magellan mission,” Hensley said. “Although this is only one data point for an entire planet, it confirms that there is modern geologic activity.”
The researchers believe that the lava flow witnessed by Magellan in 1991 was similar to that released by the 2018 Kilauea eruption in Hawaii.
“This was a needle in a haystack search with no guarantee that the needle exists,” Herrick said. “Finding a change that could be clearly confirmed as real was definitely a surprise. We were pretty sure that Venus is volcanically active, but we didn’t know if eruptions occur every few months, years, once every 10,000 years or longer. All possibilities could have fit with 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 basaltic intraplate volcanoes such as Hawaii, Galapagos- the islands, the Canary Islands, etc.”
Although it is possible that an earthquake may have triggered the collapse of the walls of the volcanic vent, the researchers believe that such activity would also have caused a volcanic eruption.
Volcanoes act as 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 gain a better understanding of Venus, just as Magellan did decades ago.
The new mission will be equipped with radar to create global 3D maps of Venus, capturing details of its surface composition, gravitational field and what played out in the planet’s past.
“Venus is an enigmatic world, and Magellan teased out so many possibilities,” Jennifer Whitten, VERITAS associate deputy scientist and assistant professor of earth and environmental sciences at Tulane University in New Orleans, said in a statement. “Now that we are very certain that the planet experienced a volcanic eruption just 30 years ago, this is a small taste of the incredible discoveries VERITAS will make.”