By understanding the record of large magmatic provinces on Earth and Venus, we can determine whether these events could have caused the current state of Venus,” said Dr. Michael J. Way of NASA’s Goddard Institute for Space Studies in New York. Way is lead author of a paper published April 22 in the Planetary Science Journal. Large igneous provinces are the products of periods of extensive volcanism lasting tens of thousands or even hundreds of thousands of years. They can deposit more than 100,000 cubic miles of volcanic rock on the surface. At the high end, that could be enough molten rock to bury the entire state of Texas half a mile deep.
Venus today boasts surface temperatures averaging around 864 F and an atmosphere that is 90 times the surface pressure of Earth. According to the study, these massive volcanic eruptions may have initiated these conditions sometime in the ancient history of Venus. In particular, the occurrence of several such eruptions in a short geological period (over a million years) could have led to an uncontrolled greenhouse effect, which started the transition of the planet from wet and mild to hot and dry.
Large fields of solidified volcanic rock cover a total of 80% of Venus’ surface, Way said. “While we’re not yet sure how often the events that created these fields occurred, we should be able to narrow it down by studying Earth’s own history.” Life on Earth has gone through at least five major mass extinction events since the emergence of multicellular life about 540 million years ago, each wiping out more than 50% of animal life on the planet.
According to this study and others before it, most of these extinction events were caused or exacerbated by the types of eruptions that produce large magmatic provinces. In the case of Earth, the climate disruptions caused by these events were not sufficient to cause a runaway greenhouse effect, as it did on Venus, for reasons that Way and other scientists are still working on.
Other NASA missions to Venus, scheduled for launch in late 2020 – the Deep Atmosphere Venus Investigation of Noble gass, Chemistry and Imaging (DAVINCI) mission and the Venus Emissivity, Radio science, InSAR, Topography, And Spectroscopy (VERITAS) mission – aim to study the origin, history and current state of Venus in unprecedented detail.
“DAVINCI’s primary goal is to narrow down the history of water on Venus and when it may have disappeared, providing more information about how the climate of Venus has changed over time,” Way said.
The DAVINCI mission will precede VERITAS, an orbiter designed to explore the surface and interior of Venus from above to better understand its volcanic and volatile history and thus Venus’ journey to its current state. Data from both missions could help scientists narrow down the exact record of how Venus may have transitioned from a wet, temperate climate to a dry, hot one. It can also help us better understand how volcanism has affected life here on Earth in the past and how it may continue to do so in the future. This study was supported by the Sellers Exoplanet Environments Collaboration (SEEC) Goddard Space Flight Center and was part of the NASA Nexus for Exoplanet System Science (NExSS) RCN.