Volcanoes may have transformed Venus into a bubble landscape: ScienceAlert

Is there anything good about volcanoes? They can be violent, dangerous and unpredictable. For modern humans, volcanoes are mostly a nuisance, sometimes an interesting visual display, and sometimes deadly.

But when there are enough of them, and when they are strong and prolonged, they can kill the planet that hosts them.

Modern Venus is a mesmerizing hellscape. The temperature rises above 464 °C (850 °F, 737 °K), which, as Universe Today readers know, is hot enough to melt lead (and spaceships).

That’s why, of all the missions Russia sent to the surface of the planet, only four managed to transmit photos before quickly succumbing to the extreme conditions of Venus.

But modern Venus can be dramatically different from ancient Venus. Some research suggests that ancient Venus had an atmosphere similar to that of ancient Earth.

The planet may also have had significant amounts of water on its surface. It is possible that simple life once existed on Venus, but there is not yet enough evidence to prove or disprove it.

A new study suggests that massive volcanic eruptions over an extended period of time may be responsible for changing the planet to what it is today. If there was simple life on ancient Venus, volcanism was its undoing.

The study also shows how strong volcanic activity has played a role in shaping Earth’s habitability, and how Earth narrowly avoided the same fate as Venus.

The study is titled “Large-Scale Volcanic Volcanism and the Heat Death of Terrestrial Worlds” and is published in The Planetary Journal. Dr. Michael J. Way of NASA’s Goddard Institute is the lead author. Way has been researching Venus for years and is the author and co-author of several papers on the planet, especially its ancient habitability.

“By understanding the record of large igneous provinces on Earth and Venus, we can determine whether these events may have caused the current state of Venus,” Way said in a press release announcing the study.

The Earth has experienced prolonged periods of continuous volcanic eruptions in its history. Large Igneous Provinces (LIPs) are the evidence for the periods, which can last hundreds of thousands of years – perhaps even millions of years.

LIPs can deposit more than 100,000 cubic miles of rock at the surface. That’s enough to bury Texas half a mile deep. On Earth, we know of many LIPs, and we know that over the last 500 million years, they have coincided with periods of climate change and mass extinctions.

The study suggests that Venus itself underwent massive volcanic eruptions that created the modern Venusian atmosphere, with its extreme temperatures and pressures. More specifically, he says intense eruptions over a period of just a million years created an invisible greenhouse effect.

The greenhouse effect is when an atmosphere prevents a planet’s heat from radiating into space. With no way to cool down, the temperature rises to extreme levels, like a greenhouse with all the vents closed.

The greenhouse effect of Venus is exacerbated by the apparent lack of tectonic plates. Earth’s plate tectonics allows heat from the planet’s interior to reach the surface by periodically opening the blanket of the mantle.

It also removes carbon dioxide from the atmosphere and into rocks through erosion and subsidence.

Our planet’s five mass extinctions, all linked to increased volcanic activity, according to this paper. (Some researchers point to a sixth mass extinction just beginning, as human activity causes increased species loss.)

The Chicxulub impact event was the main driver of the Permian-Triassic extinction that wiped out the dinosaurs, but volcanic activity also played a role. While the extinction of the Chicxulub dinosaurs is well known and widely publicized, volcanic activity has been the main driver of extinctions on Earth.

Life on Earth suffered greatly from strong and sustained volcanic activity. But it always recovered and the volcanoes never caused an overt greenhouse effect, while Venus still suffers from the effect to this day. What’s the difference?

The scale of the explosions had something to do with it. The surface of Venus is 80% covered with solidified volcanic rock. Sulfur in the atmosphere is also evidence of intense volcanic activity. And the surface of Venus has fewer craters than expected, indicating abundant volcanic activity over the past hundreds of millions of years.

But the study should make anyone uncomfortable. Although the Earth has avoided the invisible greenhouse effect, it may have narrowly avoided it.

Untangling the history of volcanism, impacts, and extinctions in Earth’s history is challenging because craters are erased. There are scientific efforts to understand the conditions in the Earth’s mantle that lead to LIPs, but this is also a difficult task.

The magmatic events that create LIPs are typically short-lived on a geologic time scale, less than 5 million years in duration. They can also be a series of pulses over a few tens of millions of years. Although they push a lot of rock to the surface, it’s the chemicals they emit into the atmosphere that drive the extinctions.

Huge amounts of CO2 the Earth’s atmosphere heated dramatically and sulfur dioxide (SO2) heating worsened. Toxic compounds such as hydrogen sulfide (H2S) and carbon monoxide (CO) also come from explosions, but only in small amounts.

Earth’s volcanic activity is similar to that of Venus because the planets are “sister planets”. They are very close in size and are both rocky planets in the inner Solar System.

But the crucial thing they share when it comes to volcanism is their bulk composition. Since they formed in the same region of the Solar System, they have very similar compositions.

In their study, the authors recreated Earth’s volcanic history in random simulations based on what is known about Earth’s volcanic activity and LIPs. “In one approach, we make a conservative estimate of the rate at which sets of near-simultaneous LIPs (pairs, triplets, and quadruplets) appear in a random history statistically the same as that of Earth,” the authors write.

“We find that LIPs closer in time than 0.1-1 million years are possible; significantly, this is less than the time over which the environmental effects of terrestrial LIPs are known to persist.”

This means that the LIP events overlap and before the planet can remove CO2 released into its atmosphere by one event, another is busy releasing more. Combine enough of these together and you have the invisible greenhouse effect. Separate lips in different parts of the planet, even under the oceans, compound the effect.

A key part of their study concerns volatility. Are LIPS causally related? This matters because if the LIP rate is variable, then this increases the possibility of overlapping or simultaneous events, which would contribute to an invisible greenhouse effect.

“How Will LIP Rate Variability Over Time Affect Concurrent Event Probabilities?” the authors write.

“During times of increased rate, the probability of simultaneous events is enhanced relative to that for the average rate. On the other hand, during times of decreased rate, this probability is reduced relative to the average. It is not obvious which of these effects prevails.”

An interesting point in all of this concerns Earth’s longest-lived LIPs. The longer one lasts, the more likely it is to overlap with another.

“[W]Find that the probability of overlapping the largest LIP in Earth’s recorded history with an event of similar size (in area) is about 30 percent. Multiple simultaneous LIPs may be important drivers of the transition from a quiescent habitable surface to a greenhouse state for terrestrial worlds, assuming they have Earth-like geochemistries and mantle convection dynamics,” the paper states.

There is a point where all of these differ. While we have fairly complete and reliable data for Earth’s lips, we have nowhere near that for Venus. But the research shows that, even with the lack of detailed data, it is possible that Venus suffered from overlapping lips that led to her destruction.

Fortunately, upcoming missions to Venus will open up this research with better data.

The Venus VERITAS (Venus Emissivity, Radio Science, InSAR, Topography, and Spectroscopy) mission is an orbiter being developed by NASA. Its launch date has yet to be scheduled, but it will be a three-year mission to image the surface of Venus in high resolution using radar and near-infrared spectroscopy.

It will provide detailed information on the planet’s impact history, volcanism, geochemistry, and more.

The DAVINCI (Deep Atmosphere Venus Investigation of Noble gases, Chemistry and Imaging) mission is also a NASA mission, but will have an atmospheric probe along with an orbiter. Once scientists have more detailed information about Venus’ atmosphere and surface, they can begin to unravel the planet’s past.

“A primary goal of DAVINCI is to constrain the history of water on Venus and when it may have disappeared, providing more information on how the climate of Venus has changed over time,” Way said.

Both DAVINCI and VERITAS will be released in the late 2020s, with DAVINCI first.

ESA is also planning an orbiter mission to Venus. It’s called EnVision, and it’s expected to launch in the early 2030s. EnVision will also study the atmosphere of Venus, but it will dig deeper, using its suite of instruments to probe the planet’s internal structure.

These results will also play a role in understanding exoplanets. Exoplanets are a growing area of ​​research, and the James Webb Space Telescope is beginning to provide better data on exoplanet atmospheres.

But it will be difficult for scientists to interpret the JWST findings without better overall models, and a more detailed understanding of our sister planet’s history will certainly improve our models of planetary atmospheres.

For some reason, Earth has remained habitable for billions of years and Venus is much worse. If Venus ever hosted ancient, simple life, it’s long gone.

(Apologies to the people who think life can go on in the clouds of Venus.)

While we may never have a full understanding of all the factors that made Earth and Venus so different from each other, volcanic activity clearly played a role. Once VERITAS, DAVINCI and EnVision have done their work, we should understand the divergent course of Venus in more detail.

This article was originally published by Universe Today. Read the original article.

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