How has Venus, Earth’s sibling planet, managed to retain a young-looking surface despite its lack of plate tectonics?
It’s a puzzle within our inner solar system that Earth and Venus, despite having comparable sizes and mass densities, function in markedly different ways, especially when it comes to the processes that mobilize materials across a planet.
Plate tectonics continually remodel Earth’s surface through the movement and collision of crustal segments, forming mountain ranges and, in certain locations, inducing volcanic activity. Venus, while possessing more volcanoes than any other planet in our solar system, only has one continuous plate covering its surface.
It’s over 80,000 volcanoes — a whopping 60 times more than Earth — have been key in rejuvenating Venus’ surface via widespread lava flows, which may still persist today.
Earlier simulations, however, struggled to validate this degree of volcanism.
To verify this, a team led by the Southwest Research Institute constructed a model of Venus’ early impact history in order to comprehend how this planet, often referred to as Earth’s twin, has managed to maintain a young-looking surface despite the absence of plate tectonics.
By comparing the primordial collision histories of Earth and Venus, they concluded that Venus likely underwent impacts of greater speed and energy, resulting in a core that’s exceedingly hot and encouraging extended periods of volcanic activity, thereby resurfacing the planet.
Professor Jun Korenaga from Yale University, a co-author of the study, said, “Our latest models show that long-lived volcanism driven by early, energetic collisions on Venus offer a compelling explanation for its young surface age. This massive volcanic activity is fueled by a superheated core, resulting in vigorous internal melting.”
Earth and Venus came into being in the same region of the solar system, formed from the gradual combination of colliding solid materials. Slight differences in their distances from the Sun altered their impact histories, especially in terms of the number and effects of these events.
This is primarily because Venus, being closer to the Sun and orbiting it faster, experienced more energetic impact conditions. Moreover, the majority of the impacts during their formative phase came from beyond Earth’s orbit, requiring higher orbital eccentricities to collide with Venus than with Earth, leading to stronger impacts.
Dr. Raluca Rufu, a Sagan Fellow and co-author from SwRI, noted, “Higher impact velocities melt more silicate, melting as much as 82% of Venus’ mantle. This produces a mixed mantle of molten materials redistributed globally and a superheated core.”
If impacts on Venus occurred at significantly higher speeds than those on Earth, a handful of major impacts could have led to drastically different consequences, influencing the subsequent geophysical evolution of the planet. The multidisciplinary team integrated their expertise in large-scale collision modeling and geodynamic processes to evaluate the long-term effects of these collisions on Venus’ evolution.
Before the consideration of high-energy impacts, geodynamic models needed specific conditions to replicate Venus’ extensive volcanism, said Korenaga.
However, “Once you input energetic impact scenarios into the model, it easily comes up with the extensive and extended volcanism without really tweaking the parameters.”
These findings come at an opportune moment as NASA committed to two new Venus missions, VERITAS and DAVINCI, in 2021, and the European Space Agency is planning another mission named EnVision.
“Venus is attracting a lot of attention at the moment,” remarked lead author Dr. Simone Marchi.
“These findings will complement the upcoming missions, and the data collected during these missions could help validate our conclusions.”
The findings of the study were published in Nature Astronomy.
Image Credit: