Michael Lee
CTVNews.ca Writer
Thursday, December 23, 2021
Signs of life on Venus?
Thursday, December 23, 2021
Signs of life on Venus?
A team of researchers discovered the presence of phosphine, a gas that is produced without oxygen on Earth, in Venus’ clouds.
This file photo, made available by NASA, shows the planet Venus made with data from the Magellan spacecraft and Pioneer Venus Orbiter. (NASA/JPL-Caltech FILE via AP)
A team of researchers has put forward a new theory suggesting possible life on the planet Venus could be making the environment more hospitable.
Published in the journal Proceedings of the National Academy of Sciences, the team from Cardiff University in Wales, MIT in Cambridge, Mass., and Cambridge University in England say potential life may be creating its own habitable environment in the clouds of Venus through a "cascade of chemical reactions," which in turn may also explain other "strange anomalies" that have puzzled scientists for decades.
Among those puzzling questions has been the presence of ammonia, a gas that was "tentatively" detected in the 1970s, and which the team says by all accounts shouldn't be produced through any chemical process known on Venus — the second planet from the sun after Mercury and before Earth.
Simply put, the group says: "Life could be making its own environment on Venus."
"We know that life can grow in acid environments on Earth, but nothing as acid as the clouds of Venus were believed to be," William Bains of Cardiff University's School of Physics and Astronomy, and a co-author of the study, said in a news release.
"But if something is making ammonia in the clouds, then that will neutralize some of the droplets, making them potentially more habitable."
The scientists note that certain life forms on Earth have the ability to produce ammonia in order to neutralize and make an otherwise highly acidic environment livable.
As part of their work, the researchers modelled a set of chemical processes to show that if ammonia is present on Venus, the gas would set off a series of chemical reactions, neutralizing surrounding droplets of sulfuric acid.
The pH level of the clouds, or how acidic or basic they are, would then increase from roughly -11 to 0, the team says. While still very acidic, the researchers say this would be within the range of acidity that life could tolerate.
The team also tested whether dust could be sweeping minerals into the clouds of Venus and causing them to interact with the sulfuric acid.
However, it was determined that a massive amount of dust would be needed, which led the team to consider ammonia.
If life were producing ammonia, the researchers say the associated chemical reactions would naturally yield oxygen, which has been identified as one anomaly on the planet.
Once ammonia is in the clouds, it would dissolve in droplets of sulfuric acid and effectively neutralize it, creating a salt-like slurry.
The most plausible explanation for where ammonia would originate from, the researchers hypothesize, is biological, as opposed to a non-biological source such as lightning, volcanic eruptions or even a meteor strike.
"Ammonia shouldn't be on Venus," study co-author Sara Seager from MIT's Department of Earth, Atmospheric and Planetary Sciences said.
"It has hydrogen attached to it, and there's very little hydrogen around. Any gas that doesn't belong in the context of its environment is automatically suspicious for being made by life."
The group says a set of proposed privately funded missions, called the Venus Life Finder Missions, of which Seager is principal investigator, could serve as an opportunity to check for the presence of ammonia — and signs of life — in the next several years.
"There are many other challenges for life to overcome if it is to live in the clouds of Venus," Bains adds.
"There is almost no water there for a start, and all life that we know of needs water. But if life is there, then neutralizing the acid will make the clouds just a bit more habitable than we thought."
This file photo, made available by NASA, shows the planet Venus made with data from the Magellan spacecraft and Pioneer Venus Orbiter. (NASA/JPL-Caltech FILE via AP)
A team of researchers has put forward a new theory suggesting possible life on the planet Venus could be making the environment more hospitable.
Published in the journal Proceedings of the National Academy of Sciences, the team from Cardiff University in Wales, MIT in Cambridge, Mass., and Cambridge University in England say potential life may be creating its own habitable environment in the clouds of Venus through a "cascade of chemical reactions," which in turn may also explain other "strange anomalies" that have puzzled scientists for decades.
Among those puzzling questions has been the presence of ammonia, a gas that was "tentatively" detected in the 1970s, and which the team says by all accounts shouldn't be produced through any chemical process known on Venus — the second planet from the sun after Mercury and before Earth.
Simply put, the group says: "Life could be making its own environment on Venus."
"We know that life can grow in acid environments on Earth, but nothing as acid as the clouds of Venus were believed to be," William Bains of Cardiff University's School of Physics and Astronomy, and a co-author of the study, said in a news release.
"But if something is making ammonia in the clouds, then that will neutralize some of the droplets, making them potentially more habitable."
The scientists note that certain life forms on Earth have the ability to produce ammonia in order to neutralize and make an otherwise highly acidic environment livable.
As part of their work, the researchers modelled a set of chemical processes to show that if ammonia is present on Venus, the gas would set off a series of chemical reactions, neutralizing surrounding droplets of sulfuric acid.
The pH level of the clouds, or how acidic or basic they are, would then increase from roughly -11 to 0, the team says. While still very acidic, the researchers say this would be within the range of acidity that life could tolerate.
The team also tested whether dust could be sweeping minerals into the clouds of Venus and causing them to interact with the sulfuric acid.
However, it was determined that a massive amount of dust would be needed, which led the team to consider ammonia.
If life were producing ammonia, the researchers say the associated chemical reactions would naturally yield oxygen, which has been identified as one anomaly on the planet.
Once ammonia is in the clouds, it would dissolve in droplets of sulfuric acid and effectively neutralize it, creating a salt-like slurry.
The most plausible explanation for where ammonia would originate from, the researchers hypothesize, is biological, as opposed to a non-biological source such as lightning, volcanic eruptions or even a meteor strike.
"Ammonia shouldn't be on Venus," study co-author Sara Seager from MIT's Department of Earth, Atmospheric and Planetary Sciences said.
"It has hydrogen attached to it, and there's very little hydrogen around. Any gas that doesn't belong in the context of its environment is automatically suspicious for being made by life."
The group says a set of proposed privately funded missions, called the Venus Life Finder Missions, of which Seager is principal investigator, could serve as an opportunity to check for the presence of ammonia — and signs of life — in the next several years.
"There are many other challenges for life to overcome if it is to live in the clouds of Venus," Bains adds.
"There is almost no water there for a start, and all life that we know of needs water. But if life is there, then neutralizing the acid will make the clouds just a bit more habitable than we thought."
Alien Life Could Theoretically Survive Within Venus's Clouds, Scientists Say
(NASA/Jet Propulsion Laboratory-Caltech)
DAVID NIELD
23 DECEMBER 2021
With an atmosphere acidic enough to strip the skin from your bones, Venus is far from what we might imagine as hospitable. But a new study backs up the idea that cocoons of life could potentially exist in the planet's corrosive clouds.
Researchers have identified a chemical pathway through which the droplets of sulfuric acid lingering in the clouds of Venus could become neutralized – perhaps to the extent that life would be able to survive on this hostile world.
At the start of this chemical pathway is the biological production of ammonia, hints of which probes detected when passing by Venus in the 1970s. According to this new study, small amounts of ammonia could dissolve into the sulfuric acid droplets. This process would transform at least some of the acid into salts, turning the liquid drops into a slurry with a pH we know life can tolerate.
"As a result, the clouds are no more acidic than some extreme terrestrial environments that harbor life," write the researchers in their published paper. "Life could be making its own environment on Venus."
An illustration of hypothetical microbial life in the clouds of Venus. (J. Petkowska)
Ammonia shouldn't occur in any significant amounts on Venus, given the limited hydrogen required would be competitively snapped up in other reactions. The researchers suggest that life might have chemical advantages to overcome this, accounting for the ammonia signal that we've recorded on Venus, among other anomalies.
These other anomalies include small concentrations of oxygen that shouldn't be there, higher-than-expected levels of water vapor, and non-spherical particles that don't match the round droplets of sulfuric acid. Chemical modeling in the lab confirmed that these strange occurrences could be explained by ammonia-producing life on Venus.
A similar sort of process happens in certain places on Earth, and indeed our own stomachs, where ammonia also has the role of neutralizing an acidic environment to make it more hospitable. On paper at least, it checks out.
Lightning, volcanic eruptions, and meteorite strikes are all other possible sources of ammonia on Venus, but according to the researchers' calculations, they would not produce enough of the stuff. Biological life potentially could.
"No life that we know of could survive in the Venus droplets," says planetary scientist Sara Seager from the Massachusetts Institute of Technology (MIT). "But the point is, maybe some life is there, and is modifying its environment so that it is livable."
This is a long way from saying that there is life on Venus, but it's an interesting hypothesis that fits the observations we have right now. What's more, the researchers have put together a list of further checks that future Venus probe missions can make to test whether this new theory holds.
And this is by no means the only interesting discussion going on about Venus. There are suggestions that there might also be phosphine in the atmosphere – which, again, could hint at biological life – but we're going to have to wait for a closer look at the planet to clear up a lot of these unknowns.
"Venus has lingering, unexplained atmospheric anomalies that are incredible," says Seager. "It leaves room for the possibility of life."
The research has been published in PNAS.
Ammonia shouldn't occur in any significant amounts on Venus, given the limited hydrogen required would be competitively snapped up in other reactions. The researchers suggest that life might have chemical advantages to overcome this, accounting for the ammonia signal that we've recorded on Venus, among other anomalies.
These other anomalies include small concentrations of oxygen that shouldn't be there, higher-than-expected levels of water vapor, and non-spherical particles that don't match the round droplets of sulfuric acid. Chemical modeling in the lab confirmed that these strange occurrences could be explained by ammonia-producing life on Venus.
A similar sort of process happens in certain places on Earth, and indeed our own stomachs, where ammonia also has the role of neutralizing an acidic environment to make it more hospitable. On paper at least, it checks out.
Lightning, volcanic eruptions, and meteorite strikes are all other possible sources of ammonia on Venus, but according to the researchers' calculations, they would not produce enough of the stuff. Biological life potentially could.
"No life that we know of could survive in the Venus droplets," says planetary scientist Sara Seager from the Massachusetts Institute of Technology (MIT). "But the point is, maybe some life is there, and is modifying its environment so that it is livable."
This is a long way from saying that there is life on Venus, but it's an interesting hypothesis that fits the observations we have right now. What's more, the researchers have put together a list of further checks that future Venus probe missions can make to test whether this new theory holds.
And this is by no means the only interesting discussion going on about Venus. There are suggestions that there might also be phosphine in the atmosphere – which, again, could hint at biological life – but we're going to have to wait for a closer look at the planet to clear up a lot of these unknowns.
"Venus has lingering, unexplained atmospheric anomalies that are incredible," says Seager. "It leaves room for the possibility of life."
The research has been published in PNAS.
William Bains, View ORCID ProfileJanusz J. Petkowski, View ORCID ProfilePaul B. Rimmer, and Sara Seage
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PNAS December 28, 2021 118 (52) e2110889118; https://doi.org/10.1073/pnas.2110889118
Contributed by Sara Seager; received November 6, 2021; accepted November 11, 2021; reviewed by David Grinspoon and Thomas Puzia
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Significance
This research provides a transformative hypothesis for the chemistry of the atmospheric cloud layers of Venus while reconciling decades-long atmosphere anomalies. Our model predicts that the clouds are not entirely made of sulfuric acid, but are partially composed of ammonium salt slurries, which may be the result of biological production of ammonia in cloud droplets. As a result, the clouds are no more acidic than some extreme terrestrial environments that harbor life. Life could be making its own environment on Venus. The model’s predictions for the abundance of gases in Venus’ atmosphere match observation better than any previous model, and are readily testable.
Abstract
The atmosphere of Venus remains mysterious, with many outstanding chemical connundra. These include the unexpected presence of ∼10 ppm O2 in the cloud layers, an unknown composition of large particles in the lower cloud layers, and hard to explain measured vertical abundance profiles of SO2 and H2O. We propose a hypothesis for the chemistry in the clouds that largely addresses all of the above anomalies. We include ammonia (NH3), a key component that has been tentatively detected both by the Venera 8 and Pioneer Venus probes. NH3 dissolves in some of the sulfuric acid cloud droplets, effectively neutralizing the acid and trapping dissolved SO2 as ammonium sulfite salts. This trapping of SO2 in the clouds, together with the release of SO2 below the clouds as the droplets settle out to higher temperatures, explains the vertical SO2 abundance anomaly. A consequence of the presence of NH3 is that some Venus cloud droplets must be semisolid ammonium salt slurries, with a pH of ∼1, which matches Earth acidophile environments, rather than concentrated sulfuric acid. The source of NH3 is unknown but could involve biological production; if so, then the most energy-efficient NH3-producing reaction also creates O2, explaining the detection of O2 in the cloud layers. Our model therefore predicts that the clouds are more habitable than previously thought, and may be inhabited. Unlike prior atmospheric models, ours does not require forced chemical constraints to match the data. Our hypothesis, guided by existing observations, can be tested by new Venus in situ measurements.
Volcanically extruded phosphides as an abiotic source of Venusian phosphine
N. Truong and J. I. Lunine
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PNAS July 20, 2021 118 (29) e2021689118; https://doi.org/10.1073/pnas.2021689118
Contributed by J. I. Lunine, June 8, 2021 (sent for review October 16, 2020; reviewed by James F. Kasting, Suzanne Smrekar, Larry W. Esposito, and Paul K. Byrne)
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Significance
Published observations suggest small amounts of phosphine in the atmosphere of Venus, and various abiotic mechanisms for its generation have been rejected in the literature, including active volcanism. We reexamine a volcanic source and find it to be sufficient to supply the observed amount of phosphine given that Venus might be subject to episodes of active volcanism and magmas originating deep in the mantle and brought up by plume volcanism.
Abstract
We hypothesize that trace amounts of phosphides formed in the mantle are a plausible abiotic source of the Venusian phosphine observed by Greaves et al. [Nat. Astron., https://doi.org/10.1038/s41550-020-1174-4 (2020)]. In this hypothesis, small amounts of phosphides (P3− bound in metals such as iron), sourced from a deep mantle, are brought to the surface by volcanism. They are then ejected into the atmosphere in the form of volcanic dust by explosive volcanic eruptions, which were invoked by others to explain the episodic changes of sulfur dioxide seen in the atmosphere [Esposito, Science 223, 1072–1074 (1984)]. There they react with sulfuric acid in the aerosol layer to form phosphine (2 P3− + 3H2SO4 = 2PH3 + 3SO42-). We take issue with the conclusion of Bains et al. [arXiv:2009.06499 (2020)] that the volcanic rates for such a mechanism would have to be implausibly high. We consider a mantle with the redox state similar to the Earth, magma originating deep in the mantle—a likely scenario for the origin of plume volcanism on Venus—and episodically high but plausible rates of volcanism on a Venus bereft of plate tectonics. We conclude that volcanism could supply an adequate amount of phosphide to produce phosphine. Our conclusion is supported by remote sensing observations of the Venusian atmosphere and surface that have been interpreted as indicative of currently active volcanism.
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