Ancient High-Energy Impacts May Have Driven Volcanic Activity on Venus
A Southwest Research Institute-led research team has modeled the early impact history of Venus to explain how Earth’s sister planet has maintained a youthful surface despite its lack of plate tectonics. Comparing the early impact histories of the two bodies, the team determined that Venus likely experienced faster, higher-energy impacts that created a superheated core that fueled volcanic activity and caused the planet to resurface.
Dr. Simone Marchi, lead author of the new paper on the finding, said, “One of the mysteries of the inner solar system is that Earth and Venus, despite their similar size and bulk density, operate in strikingly different ways, particularly affecting mass transfer processes within the planet.” told the journal Nature Astronomy.
Earth’s shifting plates are constantly reshaping its surface as chunks of crust collide to form mountain ranges and, in some places, promote volcanic activity. Venus has more volcanoes than any other planet in the solar system, but only one continuous plate on its surface; its more than 80,000 volcanoes, 60 times more than on Earth, have played a major role in renewing its surface through lava floods. Previous simulations have struggled to create scenarios that support this level of volcanic activity.
Our latest model shows that long-lived volcanism triggered by an early energetic impact on Venus is a compelling explanation for its young surface age,” said Professor Jun Korenaga of Yale University. This massive volcanic activity is fueled by an ultra-hot core, resulting in vigorous internal melting.”
This high resolution (1 million particles) computer simulation illustrates an 1,800-mile-diameter (3,000-kilometer) projectile striking Venus head-on at 18 miles per second (30 km/s). On the left, the colors indicate different materials — brown for Venus’ core; white for the projectile’s core; and green for the silicate mantle of both objects. The colors on right side indicate the temperature of the materials. Credit: Southwest Research Institute
Earth and Venus are two rocky planets formed by the gradual merging of solid materials that collided with each other in the same vicinity of the solar system. Slight differences in distance from the Sun changed the history of the collisions, especially the number and consequences of the collisions.
These differences arise because Venus is closer to the Sun and is moving around the Sun at higher speeds, making the collision conditions more energetic. In addition, the collisional growth tails are generally dominated by impactors originating from outside Earth’s orbit, which require higher orbital eccentricity to impact Venus than Earth, resulting in more powerful collisions.
The higher impact velocity can dissolve as much as 82% of the silicates in the Venusian mantle.” “This produces a mixed mantle of molten material redistributed on a global scale and a superheated core.”
A Southwest Research Institute-led team has modeled the early impact history of Venus to explain how Earth’s sister planet has maintained a youthful surface despite lacking plate tectonics. The new model suggests that the planets’ distances from the Sun resulted in higher-energy, higher-velocity impacts to Venus. These powerful collisions created a superheated core that promoted extended, extensive volcanism and resurfaced the planet. Credit: Southwest Research Institute
Ancient High-Energy Impacts May Have Driven Volcanic Activity on Venus
If impacts on Venus were significantly faster than on Earth, it is possible that some of the larger impacts could have had dramatically different consequences with important implications for the subsequent geophysical evolution of the planet. The interdisciplinary team combined expertise in large-scale impact modeling and geodynamic processes to assess the consequences of collisions on the long-term evolution of Venus.
The team’s team member, Dr. J. M. Harris, said, “The internal conditions on Venus are not well known, and before we could consider the role of high-energy impacts, the geodynamic model needed special conditions to achieve the kind of large-scale volcanic activity seen on Venus. “Once the high-energy collision scenario is input into the model, extensive and extended volcanic activity can be easily derived without adjusting any parameters.
And the timing of this new explanation is serendipitous: in 2021, NASA will embark on two new Venus missions, VERITAS and DAVINCI, and the European Space Agency is planning a mission called EnVision.
There is a lot of interest in Venus right now,” said Dr. Lindsey. These discoveries are synergistic with the upcoming missions, and the mission data will help confirm the discoveries.
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