A new analysis of mysterious structures on Venus known as coronae has revealed the likely presence of tectonic activity on the cloudy planet.
While previous studies indicated Venus does not possess tectonic plates like Earth, the new analysis, which involved a fresh look at data collected by NASA’s Magellan mission, says the mysterious structures were likely caused by rising magma, inducing a tectonic shift in the planet’s upper mantle and crust, called the lithosphere.
According to the research team behind the new analysis, understanding how a corona forms on a planet without tectonic plates could fill in knowledge gaps about the planet’s history and potentially offer a glimpse into Earth’s enigmatic tectonic past.
Mysterious Structures on Venus Found in the 1990s
In 2020, scientists announced the detection of phosphine gas in Venus’ clouds, sparking a debate about potential biological origins. Several follow-up analyses have offered support for the original detection, but the controversy remains.
Decades earlier, NASA’s Magellan mission used a sophisticated radar system to look through Venus’ thick atmosphere at the surface below. Beginning in 1990, a team from NASA’s Jet Propulsion Laboratory tasked Magellan with mapping the planet’s surface. The effort resulted in a topographic map that detailed the hills and valleys of the planet, the most detailed look at Venus’ surface to date.
While Magellan did not detect any signs of life, the mission discovered several mysterious structures on Venus that confused mission scientists as to how they could have formed. Several follow-up analyses have found additional coronae on the planet, but the debate about how they were made is still unresolved.
“Coronae are abundant on Venus,” said study coauthor Anna Gülcher, an Earth and planetary scientist at the University of Bern in Switzerland. “They are very large features, and people have proposed different theories over the years as to how they formed.”
In their study, Gülcher and colleagues took a fresh look at the Magellan data to see if new techniques could reveal fresh insights. Their potentially ground-shaking results could reshape our understanding of the second planet from the sun and potentially offer fresh insights into Earth’s enigmatic tectonic history.
Gravity Data Reveals Tectonic Activity in the Majority of Coronae Studied
Since Magellan, hundreds of coronae have been identified on Venus. Oval in shape, with what the researchers described as a “concentric fracture system” surrounding them, the mysterious structures on Venus can range from a dozen miles to hundreds of miles across. Since many of the coronae have been found in locations where the planet’s lithosphere is thin and the heat flow beneath the surface is high, the research team looked for signs that these coronae may be caused by rising magma pushing against the lithosphere from below.
The team’s first step was to develop sophisticated 3D geodynamic models of the planet. Next, the researchers input the topography data captured by Magellan. Unlike previous models, the team also included gravity data captured by the 1990s mission.
After running several simulations for plume-induced coronae, the team compared the data to the raw Magellan data. According to a statement issued by the research team announcing their findings, the addition of the gravity data “proved crucial” in detecting less dense, less hot, and buoyant plumes beneath the planet’s surface that “couldn’t be discerned from topography data alone.”
“By combining gravity and topography data, this research has provided a new and important insight into the possible subsurface processes currently shaping the surface of Venus.” said the study’s lead author, Gael Cascioli, assistant research scientist at the University of Maryland, Baltimore County, and NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
Further analysis showed that 52 of the 75 coronae studied had indications of hot, buoyant material beneath them. The team believes this material is the likely cause of these coronae. Other potential processes for the coronae are also discussed, including subduction (where one layer pushes another down) and lithospheric dripping, “where dense accumulations of comparatively cool material sink from the lithosphere into the hot mantle.” However, the researchers believe the likeliest cause of most coronae involves tectonic activity resulting from rising magma.
“The most exciting thing for our study is that we can now say there are most likely various and ongoing active processes driving their formation,” Gülcher said. “We believe these same processes may have occurred early in Earth’s history.”
In Venus Veritas
Although Magellan’s mission ended over 30 years ago in 1994 when mission planners commanded the spacecraft to plunge into the planet’s atmosphere, NASA’s JPL is aiming to launch another mission to study the planet in 2031. Dubbed VERITAS (Venus Emissivity, Radio science, InSAR, Topography, and Spectroscopy), the mission will use synthetic aperture radar to generate 3D global maps. The team hopes these sharper images of the mysterious structures on Venus will offer more detail about the planet’s tectonic activity.
According to study coauthor Suzanne Smrekar, a planetary scientist at JPL and principal investigator for VERITAS, the mission’s most tantalizing data may come from its radio tracking system. Designed to measure the planet’s gravitational field, this system could reveal critical insights about the planet’s interior that may affect the coronae’s formation
“The VERITAS gravity maps of Venus will boost the resolution by at least a factor of two to four, depending on location — a level of detail that could revolutionize our understanding of Venus’ geology and implications for early Earth,” Smrekar explained.
Study coauthor Erwan Mazarico, also at Goddard, will co-lead the VERITAS gravity experiment. Depending on the findings, the team believes their work could provide a “unique window” into Earth’s own tectonic past.
“Coronae are not found on Earth today,” Cascioli said. “However, they may have existed when our planet was young and before plate tectonics had been established.”
Christopher Plain is a Science Fiction and Fantasy novelist and Head Science Writer at The Debrief. Follow and connect with him on X, learn about his books at plainfiction.com, or email him directly at christopher@thedebrief.org.