Models suggest that Venus’ overheated core could lead to prolonged volcanism and prolonged surface recovery. A team led by the Southwest Research Institute has modeled the early collision history of Venus, explaining how Earth’s sister planet retains a youthful surface despite its lack of plate tectonics.

By comparing the early collision histories of Earth and Venus, Venus is believed to experience higher velocity, high-energy impacts. These impacts led to sustained volcanism and the formation of an overheated core, which led to the resurfacing of the planet.

Understanding inner planet differences

Lead author of a new paper on the findings in Nature Astronomy, Dr. “One of the mysteries of the inner Solar System is that, despite their similar sizes and mass densities, Earth and Venus move in dramatically different ways, particularly influencing the processes that move materials across the planet,” said Simone Marchi.

A team led by the Southwest Research Institute has modeled the early collision history of Venus, explaining how Earth’s sister planet retains a youthful surface despite its lack of plate tectonics. The new model suggests that the planets’ distance from the Sun causes Venus to collide with more energy and speed. These powerful collisions created a superheated core that fueled extensive, large-scale volcanism and planetary healing. Authorship: South-Western Research Institute

Plate tectonics and volcanism on Venus and Earth

Earth’s shifting plates are constantly changing its surface, as parts of the Earth’s crust collide to form mountain ranges and encourage volcanism in places. Venus has more volcanoes than any other planet in the Solar System, but only has one solid plate on its surface. More than 80,000 volcanoes – 60 times more than on Earth – have played an important role in regenerating the planet’s surface through lava flows that can continue to this day. Previous simulations have attempted to create scenarios to support this level of volcanism.

Early collision and volcanism

“Our latest models show that the long-term volcanism caused by early energetic collisions on Venus is a convincing explanation for the young surface age,” said co-author Professor Jun Korenaga of Yale University. “This massive volcanic activity is fueled by an overheated core, leading to a powerful internal meltdown.”

This high-resolution computer simulation (1 million particles) shows a 1,800-mile (3,000-kilometer) diameter bullet hitting Venus at 18 miles per second (30 km/h). The colors on the left represent different materials — brown, the core of Venus; white for the shell core; and green for the silicate cover of both objects. The colors on the right show the temperature of the materials. Authorship: South-Western Research Institute

Planet formations and impact histories

Earth and Venus formed in the same part of the solar system when solid materials collided with each other and gradually coalesced to form two rocky planets. Small differences in the distances of the planets from the Sun changed the history of their influence, especially the number and outcome of these events. These differences occur because Venus is closer to the Sun and moves around it faster, creating the conditions for an impact. Additionally, the collision tail tends to be dominated by impactors originating from beyond Earth’s orbit, requiring higher orbital eccentricities to collide with Venus rather than Earth, causing stronger shocks.

internal conditions of Venus

Sagan collaborator and SwRI co-author Dr. “Higher impact velocities melt more silicate, melting as much as 82% of Venus’ mantle,” said Raluka Rufu. “This creates a globally redistributed mixed mantle of molten material and a superheated core.”

Had the collision with Venus been significantly faster than the one with Earth, several major collisions could have had significantly different outcomes, with important consequences for subsequent geophysical evolution. The multidisciplinary team combined its expertise in modeling large-scale collisions and geodynamic processes to evaluate the consequences of these collisions for the long-term evolution of Venus.

Implications for future research

“The internal conditions of Venus are not well known, and geodynamic models required special conditions to reach the massive volcanism we saw on Venus before we considered the role of energetic influences,” Korenaga said. Said. “If you add energy shock scenarios to the model, it can easily occur with large-scale and extended volcanism without much parameter adjustment.” Source