Three of Venus’s largest rift valleys are widening right now — or stopped doing so so recently that the geological evidence is still fresh. That finding comes from the first high-resolution, three-dimensional computer simulations of Venusian rift dynamics, published July 24, 2026 in Nature Geoscience by researchers at ETH Zurich. The study gives mission planners their most precise map yet of where the planet’s geological engine is still running — and does it just as the missions designed to investigate those sites face significant funding uncertainty.
The concept at the core of the research is straightforward: on Earth, rift valleys grow tall ridges on their flanks as the crust pulls apart, but those ridges erode away over millions of years through rain, rivers, and ice. Venus has none of those agents. When a rift valley stops moving on Venus, its flanks don’t erode — they slowly subside through a process called isostatic relaxation, as the crust settles toward gravitational equilibrium. That means wide, tall flanks signal youth and activity. Flat, subdued flanks signal an ancient, tectonically dead rift. It is the first time this diagnostic mechanism has been tested with a realistic 3D model.
What Simulations Can Do That Earlier Models Could Not
Previous studies of Venusian rifting used two-dimensional models with simplified assumptions about how rock behaves: incompressible, and either purely viscous or purely plastic. The ETH Zurich team used a three-dimensional thermomechanical code called I3ELVIS, which treats rock as visco-elasto-plastic and compressible — meaning it can spring back elastically, flow permanently, or fracture, depending on conditions. The code also incorporates grain-size evolution in the mantle, modeling how the olivine and pyroxene minerals that make up the mantle weaken or strengthen as they deform.
The models ran on ETH Zurich’s Euler computing cluster and simulated a domain roughly 1,024 km (636 miles) wide by 512 km (318 miles) deep. The team tested three types of crustal material — plagioclase (weakest), dry diabase, and mafic granulite (strongest) — and three extension rates: 1, 3, and 10 centimeters (0.4 to 3.9 inches) per year. After the simulated rifts reached maturity, the team turned off the extension and watched how the topography evolved over tens to hundreds of millions of years of simulated relaxation. That relaxation phase — which had never been modeled in prior Venusian rift studies — turned out to be the key to the diagnostic.
The result: a rift valley with wide flanks (greater than 100 km, or 62 miles) can only have those flanks if it is still actively extending, or if it stopped extending within the past few tens of millions of years. After approximately 100 million years of relaxation, the models show rift flanks shrinking to widths below 30 to 50 km (19 to 31 miles), losing their diagnostic signature entirely. For a planet whose age is measured in billions of years, “a few tens of millions of years” is not deep geological time — it is geologically recent.
Ganis, Dali, and Devana Chasmata: Venus’s Three Suspects
With the diagnostic tool established, the team compared their model outputs to real topographic data from NASA’s Magellan spacecraft, which mapped more than 98% of Venus’s surface between 1990 and 1994. The comparison focused on three rift systems: Ganis Chasma and Dali Chasma, both located in the Atla Regio volcanic rise, and Devana Chasma in Beta Regio.
The median rift flank width for Ganis Chasma is approximately 160 km (99 miles). For Dali Chasma, it is approximately 110 km (68 miles). For Devana Chasma, the flanks exceed 180 km (112 miles) in median width. All three exceed the 100 km threshold the models establish as diagnostic of recent or ongoing activity. All three match the simulated signature of active rifts undergoing extension at rates of 3 to 10 centimeters (1.2 to 3.9 inches) per year.
Together, Venus’s rift systems span approximately 40,000 km (24,855 miles) and cover around 8% of the planet’s surface. Individual systems like Devana Chasma can extend for thousands of kilometers — rivaling the East African Rift Valley in scale (the African system stretches approximately 6,500 km, or 4,000 miles), though Venus’s versions appear to have formed and evolved without the plate-tectonic machinery that drives Earth’s continental rifting.
The extension rates the models require to match observed topography are notably high — comparable to fast terrestrial continental rifting, such as the rates measured in parts of the Afar region of East Africa. The ETH paper suggests this faster-than-expected rate is likely driven by active mantle plumes — rising columns of anomalously hot rock — rising beneath Atla and Beta Regiones. Prior optical and radar observations had already detected what appeared to be active volcanism at Ganiki Chasma, which is adjacent to Ganis Chasma, and at Ganis Chasma itself. The new simulations provide an independent geodynamic line of evidence that these regions are still geologically alive.
“The results help us to better assess the tectonic activity on Venus,” said Taras Gerya, Professor of Geodynamics at ETH Zurich’s Department of Earth and Planetary Sciences and senior author of the paper, in the ETH Zurich press release. “They also could help pinpoint active regions worthy of detailed investigation for the future missions to Venus.”
The lead author, Xi Yang, conducted the research as part of his Master’s studies under Gerya’s supervision. Co-author Anna J.P. Gülcher, now at the University of Freiburg and the University of Bern’s Center for Space and Habitability, contributed to result interpretation and scientific discussion.
Why Venus Lacks Erosion — and Why That Matters
The reason Venus’s rift flanks preserve a geological record that Earth’s do not comes down to a single difference: Venus has no water cycle. Surface temperatures average about 465°C (869°F) — hot enough to melt lead — and the atmosphere is a dense blanket of carbon dioxide pressing down at roughly 90 times Earth’s sea-level pressure. There is no rain, no ice, no river systems, and no ocean. The geological processes that reshape Earth’s topography continuously are simply absent on Venus.
That absence is precisely what makes rift flank width diagnostic on Venus in a way it cannot be on Earth. On Earth, an ancient rift valley like the East African Rift has its flanks shaped partly by tectonic history and partly by tens of millions of years of erosion and sedimentation. Separating the two signals is impossible without extensive additional data. On Venus, the signal is almost entirely tectonic — the topography is a direct record of the planet’s mechanical and thermal history, uncontaminated by surface weathering. The ETH Zurich team’s 3D models are the first to formally exploit that property as a chronometer.
The study also establishes that Venus’s crust in rifted regions is likely composed of dry diabase or mafic granulite — a strong, iron- and magnesium-rich rock consistent with the basaltic composition estimated from Soviet-era Venera lander measurements. The weaker plagioclase crust cannot produce the steep, wide rift flanks observed in the Magellan data. And the models require a lithosphere at least about 150 km (93 miles) thick to allow rifting at all — a thinner lithosphere fails to localize strain efficiently in the mantle. This 150 km figure is consistent with prior independent estimates from flexure and geodynamic studies.
Why Earth’s Sister Planet Went Wrong — and What Venus Can Tell Us
Venus and Earth are almost identical in size and bulk composition, formed from similar materials in the same region of the early solar system. Yet they became radically different worlds. Earth developed liquid oceans, a biosphere, and plate tectonics — the recycling engine that regulates atmospheric carbon and makes the planet’s surface habitable over billions of years. Venus became a dry, crushingly hot hellscape with no sign of plate tectonics and an atmosphere that traps heat far beyond what sunlight alone would produce.
Understanding why those two trajectories diverged is one of the central questions of planetary science. Active geological processes on Venus — an interior still warm enough to drive mantle plumes and rift extension — provide fresh constraints on the models scientists use to study that question. If Venus’s interior is still losing heat through rifting and volcanism, it has not undergone the kind of catastrophic resurfacing event some models predict (in which the planet’s entire surface would be replaced in a geological instant, roughly 500 to 800 million years ago, and then go geologically quiet). Instead, it may be operating in a more continuous regime — different from Earth’s plate tectonics but not simply a stagnant, dead planet either.
The ETH Zurich study’s findings also carry implications beyond Venus. As astronomical instruments improve and the catalog of confirmed rocky exoplanets grows, planetary scientists increasingly need tools to infer the interior states of distant worlds from surface observations alone — because we cannot send spacecraft to all of them. The rift-flank-width diagnostic developed in this study is in principle applicable to any planetary body imaged at sufficient resolution. A world with wide, fresh-looking rift flanks and no erosion agents is a world with a geologically recent interior signature — a framework exportable to rocky exoplanet characterization.
Does This Mission Fleet Have the Right Targets — and Will It Fly?
The ETH Zurich study’s most immediate practical consequence is for mission targeting. Ganis, Dali, and Devana Chasmata are now the highest-confidence candidates for recent or ongoing tectonic activity on Venus, confirmed by independent geodynamic modeling for the first time. The orbital instruments needed to investigate these sites at higher resolution than Magellan — particularly synthetic aperture radar capable of detecting centimeter-scale surface changes — are precisely what the upcoming Venus mission fleet is designed to carry.
ESA’s EnVision mission, which is currently under construction by Thales Alenia Space, is scheduled to launch in November 2031 aboard an Ariane 64 rocket. After a 15-month cruise and an 11-month aerobraking phase, it will begin science operations in approximately 2034, orbiting Venus once roughly every 90 minutes. The mission carries a radar sounder, a spectrometry suite, and — in the original plan — a synthetic aperture radar called VenSAR, contributed by NASA, that would map the surface at a resolution more than ten times sharper than Magellan’s. ETH Zurich geophysics professors Gerya and Paul Tackley are directly involved in instrument development for the mission.
The mission’s total budget is €610 million (approximately $705 million USD; exchange rate approximate as of article production).
NASA’s DAVINCI mission, an orbiter and atmospheric probe, received $99 million in funding through the 2026 U.S. congressional appropriations bill and is targeting launch in the 2030 to 2031 window. NASA’s VERITAS mission, also a Venus orbiter, is targeted for 2031 but as of March 2026 was described by NASA’s planetary science division director as “ramping up slowly,” following years of setbacks stemming from workforce issues at the Jet Propulsion Laboratory.
The budget picture is not reassuring. In March 2026, NASA planetary science division director Louise Prockter acknowledged that the agency’s 2026 appropriation is approximately $200 million below the 2025 level, and stated directly: “It is going to be a challenge to get all three Venus missions to continue.” Under active discussion is whether NASA will be able to deliver VenSAR — the radar instrument for EnVision — on schedule. Missing EnVision’s launch window, which has no flexibility beyond 2033 due to planetary alignment constraints, would delay the mission by at least three years.
The ETH Zurich study has just handed mission planners the most precise scientific justification yet for investigating the three chasmata. Whether that justification translates into funded, launched, and operational instruments remains an open question that depends on budget negotiations in Washington, not on geology on Venus.
What Is Next for Venusian Rift Research
The ETH team acknowledges several limitations of the current models. They use a homogeneous initial lithosphere, which does not account for the real heterogeneity in crustal thickness and composition that exists across Venus — variations that could affect how quickly rifts develop and how fast they relax. The models also do not incorporate the interaction between rifting and mantle plumes in three dimensions, nor the multidirectional extension that appears to be present at Atla and Beta Regiones. Future studies will need to address those complexities.
At the same time, the study’s approach points toward increasingly powerful geodynamic tools. As computational capacity grows, models will be able to include more realistic lithospheric structures and more complete thermochemical systems. And when EnVision and VERITAS eventually reach Venus — if they are funded and launched as planned — the high-resolution radar mapping they carry will provide a new global topographic dataset that makes the rift-flank diagnostic far more precise. The Magellan data the ETH team used has a lateral resolution of approximately 10 to 25 km (6 to 16 miles); future instruments will resolve features more than ten times smaller.
The study was funded partly by the Swiss National Science Foundation (grants 200021_192296 and 200021-231594) through the EnVision VenSpec-H ESA project, and by the Volkswagen Foundation. The modeling data are publicly available via Zenodo.
Venus, it turns out, is not a finished story. Three of its largest rift valleys are still growing — or were so recently that even the geological clock has barely moved. The machines scientists are building to read that story more clearly are either under construction or at financial risk. Whether the instruments arrive before the funding window closes is now as pressing a question as the science itself.
Frequently Asked QuestionsHow do scientists know Venus’s rift valleys are still active if no spacecraft is there now?
They used the topography from NASA’s Magellan radar mission, which mapped more than 98% of Venus’s surface at roughly 10 to 25 km (6 to 16 miles) resolution between 1990 and 1994. The ETH Zurich team built 3D computer simulations showing that rift valleys develop wide ridges on their flanks when they are actively extending or have recently stopped, and that those ridges flatten relatively quickly once tectonic movement ceases. Comparing the simulations to Magellan measurements of Ganis, Dali, and Devana Chasmata, they found that all three systems still have flanks wide enough to indicate recent or ongoing activity. No spacecraft has to be watching in real time — the topography itself is the record.
What is a rift valley, and why are Venus’s rift valleys so much bigger than Earth’s?
A rift valley forms when the lithosphere — the rigid outer layer of a planet — is pulled apart by extensional forces, causing the crust between two faults to drop down relative to the surrounding rock. On Earth, this process is driven by plate tectonics: moving plates create divergent boundaries where the crust stretches and thins. Venus has no Earth-style plate tectonics, so its rifting is driven instead by mantle plumes and localized extensional forces. Because Venus’s crust appears to be composed of strong mafic rock (dry diabase or granulite), it can sustain larger fault offsets before breaking, producing rift flanks with greater elevation differences. The total Venusian rift system extends roughly 40,000 km (24,855 miles).
Will the upcoming Venus missions actually be able to study these rift systems?
Potentially, yes — but mission funding is uncertain. ESA’s EnVision mission is currently under construction and scheduled to launch in November 2031, with science operations starting around 2034. It is designed to map Venus’s surface at much higher resolution than Magellan. However, NASA’s contribution to EnVision — a synthetic aperture radar called VenSAR — is under budgetary pressure. NASA’s planetary science division director stated in March 2026 that getting all three Venus missions (EnVision, DAVINCI, and VERITAS) funded and flying simultaneously “is going to be a challenge.” Ganis, Dali, and Devana Chasmata are now the best scientifically justified targets, but whether the instruments designed to characterize them will actually arrive depends on budget decisions, not science.
What does Venus’s active geology tell us about why it became so different from Earth?
It tells us that Venus’s interior is still generating enough heat to drive geological processes — rifting, volcanism, and possible mantle plume activity — billions of years after the planet formed. This rules out models in which Venus underwent a complete, catastrophic resurfacing event and then went entirely geologically quiet. Instead, Venus appears to operate in a more sustained but non-plate-tectonic geological regime — sometimes described as “squishy lid” tectonics, in which the lithosphere deforms and loses heat through localized mechanisms rather than through the global recycling system Earth uses. Understanding that regime more precisely is one of the key scientific goals of the upcoming Venus mission fleet, because it constrains models of how rocky planets in general — including those being discovered around other stars — evolve over geological time.