(ORDO NEWS) — High-speed collisions early in Venus’s history could help understand the differences between Venus and its rocky sister planet Earth, according to new simulations.
The two planets are similar in many aspects. They have similar sizes, masses and densities, and they are also located at approximately the same distance from the Sun. However, some of the key differences – such as habitability, atmospheric composition, and plate tectonics – have yet to be explained.
High-speed cosmic collisions could help explain why Earth is habitable and Venus is not, according to a new study.
“In the early stages of the solar system’s formation, collisions between space bodies were inevitable,” said Simone Marche, a planetary scientist at the Southwest Research Institute, USA. – If a space body that collided with a planet had a diameter greater than, say, hundreds of kilometers, then such a collision had a profound effect on the layers of material located deep in the interior of the planet, as well as on its surface and atmosphere. Such gigantic collisions affected the entire planet. ”
Recent work by another group of researchers showed that cosmic bodies during the late accretionary phase of the evolution of Venus, from 4.5 to 4.0 billion years ago, could bombard the planet, moving, on average, at higher speeds than bodies that bombarded the Earth. More than a quarter of collisions of space objects with Venus took place at speeds in excess of 30 kilometers per second (about 107,000 kilometers per hour).
This new study shows that large, high-speed collisions of space bodies with Venus resulted in the formation of twice as much melt when compared to Earth. High-speed collisions with Venus at acute angles to the vertical could lead to complete melting of the mantle, according to this new work.
Even one such powerful collision with Venus could interrupt and even completely “reset” evolution on the planet, according to Marche. At times, Venus could transform from a solid rocky body into a molten ball, as a result of which there was a change in the mineralogy and physical structure of the planet’s interior and its surface.
Any early-formed atmosphere could have been completely lost into space as a result of a collision and replaced with volatile gases released from the melt. A single high-speed collision could ultimately determine the possibility of plate tectonics on the planet, contributing greatly to the creation of habitable conditions on the planet, Marche suggests.
Work presented at the 2021 American Geophysical Union Fall Meeting.
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