Venus — a scorching planet dotted with tens of thousands of volcanoes — might be even more geologically dynamic near its exterior than previously believed. Recent calculations by scientists at Washington University in St. Louis indicate that the planet’s outer shell could be perpetually shifting, an unanticipated process known as convection that might elucidate numerous volcanoes and other characteristics of the Venusian terrain.
“No one had truly contemplated the potential for convection within Venus’ crust before,” remarked Slava Solomatov, a professor of earth, environmental, and planetary sciences in Arts & Sciences. “Our calculations imply that convection is feasible and perhaps even probable. If accurate, it offers us fresh perspectives on the planet’s development.”
The research was published in Physics of Earth and Planetary Interiors. Chhavi Jain, a postdoctoral associate at WashU, is a co-author.
Convection, a recognized process in geology, takes place when warmed material ascends toward a planet’s surface, while cooler materials descend, creating a perpetual conveyor belt effect. On Earth, deep mantle convection generates the energy responsible for plate tectonics.
The Earth’s crust, which is about 40 kilometers thick in continents and 6 km in ocean basins, is too thin and cool to facilitate convection, Solomatov clarified. However, he hypothesized that the crust of Venus might possess the appropriate thickness (possibly 30-90 km, varying by location), temperature, and mineral composition to sustain that conveyor belt.
To verify this possibility, Solomatov and Jain utilized new fluid dynamics theories developed in their laboratory. Their findings suggested that Venus’ crust could indeed accommodate convection — a completely new framework for considering the geology of the planet’s surface.
In 2024, the two researchers employed a similar methodology to establish that convection is unlikely to occur in Mercury’s mantle due to that planet’s small size and significant cooling since its formation 4.5 billion years ago.
In contrast, Venus is a searing planet both internally and externally. Surface temperatures can soar to 870 degrees Fahrenheit, and its volcanoes and other surface attributes demonstrate evident signs of melting. Scientists have long been curious about how heat from the planet’s core could be conveyed to the surface. “Convection within the crust could represent a crucial yet missing component,” Solomatov stated.
Convection close to the surface might also affect the type and distribution of volcanoes on the Venusian landscape, according to Solomatov. In 2023, Paul Byrne, an associate professor of earth, environmental, and planetary sciences in Arts & Sciences, released an atlas of 85,000 volcanoes on Venus based on radar imagery from NASA’s Magellan mission from the early 1990s. Solomatov mentioned that he and Byrne have contemplated potential future collaborations merging mathematical modeling with surface observations of Venus for enhanced understanding of the planet’s geology.
Solomatov is optimistic that future missions to Venus could yield even more comprehensive data on the crust’s density and temperature. If convection is happening as anticipated, certain regions of the crust should be hotter and less dense than others, variations that could be detected via high-resolution gravity measurements.
However, an even more captivating target is Pluto, the icy dwarf planet located at the far ends of the solar system. Imagery from the New Horizons mission unveiled extraordinary polygonal formations on Pluto’s Sputnik Planitia area, reminiscent of plate margins on Earth. These polygons form due to slow convection currents within a 4 km-thick layer of solid nitrogen ice. “Pluto is likely just the second planetary body in the solar system, aside from Earth, where the convection driving tectonics is visibly apparent on the surface,” Solomatov remarked. “It’s a compelling system that we still need to comprehend.”
Originally published on the Ampersand website
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