Venus uninhabitable due to high-speed impacts?

New models suggest that large, high-speed impacts during Venus' ancient history could reconcile the differences between Venus and its rocky sister planet, Earth. The two planets are similar in many ways. They have similar dimensions, masses and densities and are relatively similar distances from the Sun. Yet some key differences - such as habitability, atmospheric composition and plate tectonics - have remained unexplained. High-speed impacts could help explain why the Earth is habitable while Venus is not, according to new research presented at the AGU Fall Meeting 2021.

Recent work by another research group has shown that the Impacting objects during Venus' late accretion phase, about 4.5-4.0 billion years ago, could have hit the planet at much faster speeds, on average, than those colliding with Earth. More than a quarter of collisions with Venus would have occurred at speeds of at least 30 kilometers per second (approximately 67,100 miles per hour).

Photo credit - Depositphotos.com New research shows that large impacts at high velocities on Venus lead to twice the melting of the mantle compared to the melting induced by the impact on Earth. High-speed impacting objects hitting Venus at a shallow angle would have caused the mantle to melt completely, according to the new research.

Venus could have gone from a solid rock body to a molten mess in moments, altering the mineralogy and physical structure of the interior and surface of the planet. Any pre-existing atmosphere would have been largely wiped out and replaced by volatile gases emerging from the merger. A single high-speed impact could have determined whether or not tectonic plates formed, which is an important aspect of habitability.

While major impacts likely affected both Earth and Venus, the latter may have undergone substantial melting and disruption due to the high speed of its impacts, setting the planets on divergent evolutionary paths. For both planets, and for the Solar System as a whole, these early collisions had major consequences on their habitability.