A team led by Southwest Research Institute has developed a model to explain how Venus has maintained a youthful surface despite the lack of plate tectonics. By comparing the collision histories of Venus and Earth, the team concluded that Venus likely experienced higher-speed, higher-energy impacts that resulted in a superheated core, leading to extended volcanism and resurfacing of the planet.
“Despite their similar size and density, Earth and Venus operate differently in moving materials through a planet,” said Dr. Simone Marchi, the lead author of a new paper published in Nature Astronomy regarding these findings.
Unlike Earth, which has shifting plates that continuously reshape its surface, Venus has only one continuous plate. However, Venus has more volcanoes than any other planet in the solar system, with over 80,000 volcanoes playing a significant role in renewing the planet’s surface through lava floods. Previous simulations struggled to explain this level of volcanism.
“Our latest models show that long-lived volcanism driven by early, energetic collisions on Venus provides a convincing explanation for its young surface,” said Professor Jun Korenaga, a co-author from Yale University. “This massive volcanic activity is fueled by a superheated core, resulting in vigorous internal melting.”
Earth and Venus were formed in the same area of the solar system, as solid materials collided and gradually combined to form both rocky planets. Differences in their distances from the Sun affected their impact histories and the number and outcome of these events. Venus’s closer proximity to the Sun and faster orbit energized impact conditions. Furthermore, the tail of collisional growth is mainly composed of impactors from beyond Earth’s orbit, requiring higher eccentricities to collide with Venus, resulting in more powerful impacts.
“Higher impact velocities caused up to 82% of Venus’ mantle to melt,” said Dr. Raluca Rufu, a Sagan Fellow and co-author from Southwest Research Institute. “This creates a mixed mantle of molten materials distributed globally and a superheated core.”
If impacts on Venus had significantly higher velocity than on Earth, a few large impacts could have had drastically different outcomes, which would have significant implications for subsequent geophysical evolution. The multidisciplinary team combined large-scale collision modeling and geodynamic processes to analyze the consequences of these collisions for Venus’s long-term evolution.
“Venus’s internal conditions are not well known, and previous geodynamic models required special conditions to explain the massive volcanism observed,” Korenaga said. “When energetic impact scenarios are included in the model, it easily predicts the extensive and prolonged volcanism without the need for parameter adjustments.”
These findings come at an opportune time, as NASA has committed to two new Venus missions, VERITAS and DAVINCI, and the European Space Agency is planning a mission called EnVision.
“There is currently significant interest in Venus,” Marchi said. “These findings will complement the upcoming missions, and the mission data may confirm the results of our research.”