For the first time, scientists have observed direct evidence of active volcanic activity on Venus, Earth’s twin planet. This discovery sets the stage for NASA’s VERITAS mission to investigate further. The evidence was found by analyzing archival radar images from NASA’s Magellan mission taken over 30 years ago, which revealed a volcanic vent changing shape and increasing significantly in size in less than a year.
Despite being similar in size and composition to Earth, Venus has a hostile surface with a thick atmosphere of carbon dioxide and sulfuric acid clouds, making it sometimes referred to as Earth’s “evil twin.” The extreme greenhouse effect on Venus has caused its surface temperature to rise to over 900 degrees Fahrenheit, making it unsuitable for life as we know it.
Scientists study active volcanoes to understand how a planet’s interior can shape its crust, drive its evolution, and affect its habitability. NASA’s upcoming VERITAS mission will study Venus from surface to core to understand how a rocky planet of similar size to Earth took a very different path, developing into a world covered in volcanic plains and deformed terrain hidden beneath a thick, hot, toxic atmosphere. Led by the agency’s Jet Propulsion Laboratory in Southern California, the mission is set to launch within a decade.
According to Robert Herrick, a research professor at the University of Alaska Fairbanks and member of the VERITAS science team, NASA’s selection of the VERITAS mission inspired him to search for recent volcanic activity in Magellan data. Despite not expecting to be successful, Herrick spent about 200 hours manually comparing images from different Magellan orbits and eventually found two images of the same region taken eight months apart exhibiting geological changes caused by an eruption.
The search and its conclusions are discussed in a new study published in the journal Science, and Herrick presented the findings at the 54th Lunar and Planetary Science Conference in the Woodlands, Texas, on March 15. The proposed VERITAS spacecraft will use its radar to produce high-resolution maps of Venus’ topographic and geological features.
This computer-generated, three-dimensional perspective of the surface of Venus shows Maat Mons, a massive volcano on the planet’s surface. The viewpoint is located 634 kilometers (393 miles) north of Maat Mons at an elevation of 3 kilometers (2 miles) above the terrain. Lava flows extend for hundreds of kilometers across the fractured plains shown in the foreground, to the base of Maat Mons.
The image was created by combining NASA Magellan mission synthetic aperture radar data with radar altimetry to develop a three-dimensional map of the surface. The vertical scale in this perspective has been exaggerated 10 times to better visualize the terrain.
Modeling a Volcano
The geological changes that Herrick found occurred in Atla Regio, a vast highland region near Venus’ equator that hosts two of the planet’s largest volcanoes, Ozza Mons and Maat Mons. While the region has long been thought to be volcanically active, there was no direct evidence of recent activity until now.
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 covered an area of less than 1 square mile (2.2 square kilometers). It had steep interior sides and showed signs of drained lava down its exterior slopes, which hinted at activity. In radar images captured eight months later, the same vent had doubled in size and become misshapen. It also appeared to be filled to the rim with a lava lake.
Although the two observations were from opposite viewing angles, they had different perspectives, making them difficult to compare. Additionally, the low resolution of the three-decade-old data made the work more complicated. To overcome these challenges, Herrick teamed up with JPL’s Scott Hensley, the project scientist for VERITAS and a specialist in analyzing radar data like Magellan’s. Together, they created computer models of the vent in various configurations to test different geological event scenarios, such as landslides.
From those models, they concluded that only an eruption could have caused 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.”
The size of the lava flow generated by the Maat Mons activity is likened by the scientists to the 2018 Kilauea eruption on the Big Island of Hawaii. Altitude data for the Maat and Ozza Mons region on the Venus surface is shown on the left, with the area of study indicated by the black box. On the right are the before (A) and after (B) Magellan observations of the expanded vent on Maat Mons, with possible new lava flows after an eruptive event.
This annotated, computer-simulated global map of Venus’ surface is assembled from data from NASA’s Magellan and Pioneer Venus Orbiter missions. Maat Mons, the volcano that has exhibited signs of a recent eruption, is located within the black square near the planet’s equator. The map provides a detailed view of the planet’s surface features, including its vast highland regions, volcanic plains, and impact craters. The data from the missions has been combined to create a three-dimensional map of the surface, allowing scientists to study the planet’s geology and understand its evolution.
Magellan’s Legacy
The VERITAS team, including Herrick and Hensley, are excited to see how the mission’s suite of advanced science instruments and high-resolution data will complement Magellan’s remarkable trove of radar imagery, which transformed humanity’s knowledge of Venus. VERITAS will use state-of-the-art synthetic aperture radar to create 3D global maps and a near-infrared spectrometer to determine the surface composition of Venus. The spacecraft will also measure the planet’s gravitational field to determine the structure of its interior, offering clues about the planet’s past and present geological processes.
Unlike Magellan’s data, which was originally cumbersome to study, VERITAS’ data will be available online to the science community. This will enable researchers to apply cutting-edge techniques, such as machine learning, to analyze the planet and help reveal its innermost secrets. These studies will be complemented by EnVision, an ESA mission to Venus set for launch in the early 2030s. The spacecraft will carry its own synthetic aperture radar (called VenSAR), which is being developed at JPL, as well as a spectrometer similar to the one VERITAS will carry. Both Hensley and Herrick are key members of the VenSAR science team.
More About the Mission
In 2021, NASA selected the VERITAS and DAVINCI missions as their next ventures to Venus under the Discovery Program. VERITAS has collaborated with several organizations, including Lockheed Martin Space, the Italian Space Agency, the German Aerospace Center, and France’s Centre National d’Études Spatiales. The Planetary Missions Program Office at NASA’s Marshall Space Flight Center in Huntsville, Alabama, manages the Discovery Program for NASA’s Science Mission Directorate’s Planetary Science Division in Washington.
The VERITAS mission is scheduled to launch in 2028 and will study Venus’ surface geology, composition, and structure using its advanced suite of instruments. The DAVINCI+ mission, which is also scheduled to launch in 2028, will study the planet’s atmosphere and search for signs of past and present life using a descent sphere and mass spectrometer. Both missions are expected to provide significant new insights into the enigmatic planet Venus.
