Models are shown Venus‘A superheated core can produce extended volcanism and long-term reactivation.
The Southwest Research Institute-led team modeled the early impact history of Venus, explaining how Earth’s sister planet maintained a youthful surface despite the absence of plate tectonics. By comparing the early collision histories of Earth and Venus, Venus is believed to have experienced faster and higher-energy impacts. These impacts led to the formation of a superheated core, which stimulated a long period of volcanism and caused the rebirth of the planet.
Understand internal planetary differences
“One of the mysteries of the inner Solar System is that, despite their size and bulk density, Earth and Venus behave differently, particularly as they affect the processes that move matter through a planet,” said Dr. Simone Marchi said.
The Southwest Research Institute-led team modeled the early impact history of Venus, explaining how Earth’s sister planet maintained its youthful surface despite the absence of plate tectonics. The new model suggests that the planets’ distance from the Sun resulted in high-energy, high-velocity impacts to Venus. These powerful collisions created a superheated core that fueled extensive and extensive volcanism and rewarmed the planet. Credit: Southwest Research Institute
Plate tectonics and volcanism on Venus and Earth
Earth’s shifting plates are constantly reshaping its surface, parts of the crust colliding to form mountain ranges, and in places promoting volcanism. Venus has more volcanoes than any other planet in the solar system, but it has only one continuous plate on its surface. More than 80,000 volcanoes — 60 times more than Earth — have played a major role in renewing the planet’s surface through floods of lava that may continue to this day. Previous simulations have struggled to create conditions to support this level of volcanism.
Early collision and volcanism
“Our latest models show that volcanism fueled by early energetic collisions on Venus provides a compelling explanation for its young surface age,” said co-author Professor Jun Korenaga from Yale University. “This massive volcanic activity is fueled by a superheated core, which causes intense internal melting.”
This high-resolution (1 million particles) computer simulation shows an 1,800-mile-diameter (3,000-km) projectile accelerating toward Venus at 18 miles per second (30 km/s). On the left, colors indicate different objects — brown for Venus’ core; the core of the projectile is white; The silicate mantle of both materials is green. The colors on the right indicate the temperature of the material. Credit: Southwest Research Institute
Planet formations and impact histories
Earth and Venus formed in the same neighborhood of the Solar System when solid material collided with each other and gradually coalesced to form the two rocky planets. Small differences in the planets’ distances from the Sun altered their impact histories, particularly the number and effect of these events. These differences occur because Venus is closer to the Sun and moves faster around it, energizing the shock state. Furthermore, the tail of collisional growth is usually dominated by shocks originating beyond Earth’s orbit, which require a higher orbital concentration to collide with Venus than with Earth, resulting in more powerful shocks.
Internal conditions of Venus
“Higher impact velocities melt more silicate, up to 82% of Venus’ mantle,” said Sagan Fellow and SwRI co-author Dr. Raluka Rufu said. “It produces a mixed mantle of globally redistributed molten material and a superheated core.”
If impacts on Venus had much higher velocities than on Earth, some large impacts would have had important consequences for subsequent geophysical evolution. The multidisciplinary team combined expertise in large-scale collision modeling and geodynamic processes to assess the consequences of those collisions for the long-term evolution of Venus.
Implications for future studies
“Venus’ internal conditions are not well known, and before considering the role of energetic impacts, geodynamic models require special conditions to achieve the massive volcanism we see on Venus,” Korenaga said. “Once you input the energetic impact scenarios into the model, it easily comes up with an extensive and extended volcanism without having to adjust the parameters.”
The timing of this new explanation is unusual. In 2021, NASA has committed to two new Venus missions, Veritas and DaVinci. European Space Agency (ESA) is planning one called Envision.
“Interest in Venus is high right now,” Marchi said. “These findings will be synergistic with future missions, and mission data will help confirm the findings.”
Reference: “Long-term Volcanic Revival of Venus, Driven by Early Collisions” by Simone Marchi, Raluca Rufu, and Jun Korenaga, 20 July 2023, Natural Astronomy.