Reshaping of Venus: High-Energy Cosmic Collisions May Have Powered Ancient Volcanism

A study led by the Southwest Research Institute (SwRI) has explored the early collisional history of Venus and Earth, concluding that Venus encountered more high-energy impacts, which led to the formation of a superheated core. This core, according to models, could have facilitated Venus’ prolonged volcanism and a younger-looking surface. Credit: Southwest Research Institute

The models propose that the overheated core of Venus might have triggered extended volcanism and a long-term process of resurfacing.

An SwRI-led group has utilized models of Venus’s early impact history to elucidate how the planet has maintained a young surface, despite not having plate tectonics, much like Earth. By contrasting the early impact histories of both Earth and Venus, it is posited that Venus was subjected to more potent, high-speed impacts. These impacts paved the way for a superheated core, which initiated long-lasting volcanism and a planetary resurfacing.

Deciphering Inner Planetary Contrasts

Dr. Simone Marchi, the lead author of the new paper published in Nature Astronomy, said, “Despite their similar size and bulk density, Earth and Venus operate in fundamentally different ways, especially concerning the processes that transport materials through a planet. This has always been a mystery of the inner solar system.”

The recent model suggests that the respective distances of the planets from the Sun led to high-energy and high-velocity impacts on Venus. The resultant powerful collisions forged a superheated core that spurred expansive volcanism and a planetary resurfacing. Credit: Southwest Research Institute

Plate Tectonics and Volcanism on Venus and Earth

Earth’s dynamic plates continuously reconfigure its surface by colliding to form mountain ranges and sometimes sparking volcanism. Venus, however, despite being home to more volcanoes than any other planet in the solar system, has only one continuous surface plate. Over 80,000 volcanoes – 60 times the number on Earth – have significantly contributed to surface renewal through volcanic activity, possibly persisting to this day. Previous models struggled to accommodate this level of volcanism.

High-Energy Collisions and Prolonged Volcanism

Professor Jun Korenaga, a co-author from Yale University, said, “Our latest models provide a compelling explanation for Venus’s young surface age, suggesting that extended volcanism was driven by early high-energy collisions. This massive volcanic activity was sustained by a superheated core, leading to intense internal melting.”

Earth and Venus, formed in the same region of the solar system, came about through a series of collisions of solid materials. The slight differences in their distances from the Sun altered their respective impact histories, mainly the frequency and the outcomes of these collisions. Venus’s closer proximity to the Sun and faster orbit resulted in high-energy impact conditions. More powerful impacts occurred due to Venus’s susceptibility to impactors originating from beyond Earth’s orbit, requiring higher orbital eccentricities.

Internal Structures of Venus

According to Dr. Raluca Rufu, a Sagan Fellow and SwRI co-author, “High-velocity impacts can melt a large amount of silicate, melting up to 82% of Venus’s mantle. This results in a globally redistributed mixed mantle of molten materials and a superheated core.”

If Venus’s impacts had significantly higher velocities than those on Earth, a few large collisions could lead to drastically different outcomes, greatly influencing the planet’s geophysical evolution. The team combined their expertise in large-scale collision modeling and geodynamic processes to evaluate the long-term evolution of Venus post these collisions.

Consequences for Upcoming Studies

Before the inclusion of energetic impacts in the model, geodynamical models required special conditions to account for Venus’s massive volcanism, Korenaga said. “However, when you factor in the energetic impact scenarios into the model, it easily explains the extensive and prolonged volcanism without requiring significant parameter adjustments.”

This discovery coincides with increased interest in Venus. NASA committed to two Venus missions, VERITAS and DAVINCI, in 2021, and the European Space Agency (ESA) is planning another mission, EnVision.

“There’s a high level of interest in Venus currently,” Marchi said. “These findings can complement the upcoming missions, and the data from these missions may help confirm our findings.”

Reference: “Long-lived volcanic resurfacing of Venus driven by early collisions” by Simone Marchi, Raluca Rufu, and Jun Korenaga, 20 July 2023, Nature Astronomy.
DOI: 10.1038/s41550-023-02037-2

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More about Venus’ Volcanism

• Southwest Research Institute
• NASA’s VERITAS mission to Venus
• NASA’s DAVINCI mission to Venus
• European Space Agency’s EnVision mission
• Nature Astronomy Journal