An SwRI-led team compared the early impact history of Venus and Earth, determining that Venus experienced higher-energy impacts creating a superheated core. Models show these conditions could create Venus’ extended volcanism and younger surface.
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.
Newswise — SAN ANTONIO —July 20, 2023 —A team led by the Southwest Research Institute has conducted a study to shed light on the youthful appearance of Venus' surface, despite the absence of plate tectonics. By comparing the early collision histories of Earth and Venus, they have uncovered that Venus likely experienced more intense and high-energy impacts, leading to a superheated core that triggered extensive volcanism, effectively renewing the planet's surface.
Dr. Simone Marchi, the lead author of a Nature Astronomy paper detailing these findings, highlighted the intriguing contrast between Earth and Venus in terms of their processes for moving materials within the planets, considering their similar size and density.
Earth's dynamic shifting plates continuously reshape its surface, creating mountain ranges and promoting volcanism at specific locations. In contrast, Venus, with just one continuous plate, boasts an astonishing number of over 80,000 volcanoes—60 times more than Earth. This abundance of volcanoes plays a crucial role in resurfacing the planet through lava floods, an ongoing process that has puzzled scientists until now.
The team's latest models propose that the source of this long-lasting and vigorous volcanic activity on Venus can be attributed to the energetic collisions it experienced during its early history. These powerful impacts caused the planet's core to become superheated, leading to extensive internal melting and continuous volcanism. This groundbreaking insight provides a compelling explanation for the surprisingly young appearance of Venus' surface. Professor Jun Korenaga from Yale University, a co-author of the study, emphasized that the massive volcanic activity on Venus owes its existence to this superheated core, driving the planet's rejuvenating processes.
Earth and Venus emerged from the same region in the solar system, where solid materials collided and gradually coalesced to give rise to these two rocky planets. However, subtle variations in their distances from the Sun influenced their impact histories, leading to distinct outcomes for each planet. The proximity of Venus to the Sun and its swifter orbital movement resulted in more energized impact conditions. Moreover, during the later stages of their formation, Venus encountered more impactors originating from beyond Earth's orbit due to its closer proximity to the Sun. These impactors required higher orbital eccentricities to collide with Venus, leading to more powerful impacts compared to those experienced by Earth.
The Sagan Fellow and SwRI co-author, Dr. Raluca Rufu, explained that the higher impact velocities on Venus caused a substantial melting of its silicate, melting up to 82% of the planet's mantle. This process created a mixed mantle of molten materials that redistributed globally and a superheated core.
The study's multidisciplinary team combined expertise in large-scale collision modeling and geodynamic processes to investigate the long-term consequences of these impacts on Venus' evolution. Prior to considering the role of energetic impacts, geodynamical models struggled to account for the extensive volcanism observed on Venus. However, once the energetic impact scenarios were incorporated into the models, they naturally explained the abundance of volcanic activity without the need for special parameter adjustments.
The timing of this new explanation is fortuitous, as NASA has committed to two new Venus missions—VERITAS and DAVINCI—in 2021, while the European Space Agency is planning its own mission called EnVision. These missions will provide valuable insights into the mysteries of Venus and help validate the findings from this research.
Dr. Marchi expressed that there is currently a significant surge in interest regarding Venus. He anticipates that these recent discoveries will complement the forthcoming missions, and the data gathered during these missions could serve to validate the findings further.
The paper “Long-lived volcanic resurfacing of Venus driven by early collisions” appears in Nature Astronomy and can be accessed at https://doi.org/10.1038/s41550-023-02037-2.
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Credit: Southwest Research Institute
Caption: An SwRI-led team compared the early impact history of Venus and Earth, determining that Venus experienced higher-energy impacts creating a superheated core. Models show these conditions could create Venus’ extended volcanism and younger surface.
Credit: Southwest Research Institute
Caption: 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.
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