An example of a simulation of a large planet hitting a Venus-like planet. The middle and right panels show Venus. The colors indicate the temperature. Simone Marchi and Raluca Rufu are credited with the Southwest Research Institute.
New modeling suggests that large, high-speed impacts during Venus' early history could reconcile the differences between Venus and Earth.
The two planets are very similar. They are similar in size, mass and densities to the Sun. Key differences such as habitability, atmospheric composition and plate tectonics are unexplained.
New research will be presented at the AGU Fall Meeting in 2021.
Simone Marchi, a planetary scientist at Southwest Research Institute, will be presenting a study on impactors on Thursday, December 16 at 9:10 a.m. There is a time for this. If an impactor was larger than a few hundred kilometers in diameter, it could have affected the deep interior of a planet. Everything about a planet would be affected by these huge collisions.
The research group found that impactors could have hit the planet at much higher speeds than those colliding with Earth. More than one-quarter of Venus's surface would have been hit at a speed of at least 30 kilometers per second.
An artistic rendering of a collision on Venus. Modelling shows that high-speed impacts could have re-melted Venus' mantle, altering its planetary evolution. Simone Marchi is the Southwest Research Institute's credit.
The research shows that the large, high-speed impacts on Venus lead to twice as much mantle melting as impact-induced melting on Earth. According to the new research, high-speed impactors hitting Venus at a shallow angle would have melted the mantle.
According to Marchi, if just one of these impactors hit Venus, it would have halted the planet's evolution. Venus could have gone from a solid rocky body to a molten mess in a matter of moments. The atmosphere would have been blasted away and replaced by gasses from the melt. Habitability is important and a single high-speed impact could determine whether or not tectonic plates formed.
The high speed of the impacts could have set the planets on different evolutionary pathways, melting and disrupting the Earth and Venus. These early collisions had consequences for both planets and the Solar System as a whole.
The Solar System was shaped by these collisions. Marchi said that it's not a stretch of the imagination to say that without these processes, we would live in a completely different environment. We need to ask how much of the planet we live on was shaped by these events.
Venus' history may have been shaped by high-speed impacts.
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