No signs of life on Venus despite strange behaviour of sulphur in atmosphere
The long-held belief that life could exist in Venus’ clouds has been rejected by a new study, which claims that sulfur’s unusual behavior in the atmosphere cannot be explained by an “air” form of aliens.
Any life form in sufficient abundance is expected to leave chemical fingerprints on a planet’s atmosphere as it consumes food and expels waste.
But scientists at the University of Cambridge found no evidence of this, after using a combination of biochemistry and atmospheric chemistry to test the “life in the clouds” hypothesis.
Astronomers have speculated for decades that sulfur in the clouds of the sun’s second planet could support life and act as a potential food source.
However, researchers said “air” life cannot explain the makeup of Venus’ atmosphere and why sulfur is “sucked” from the air.
“We wanted life to be a possible explanation, but when we ran the models, it turned out not to be a viable solution,” said lead author Sean Jordan of the Cambridge Institute of Astronomy.
The belief that life could exist in Venus’ clouds has been rejected by a new study, which claims that sulfur’s unusual behavior in its atmosphere cannot be explained by an “air” form of aliens. Pictured is an artistic impression of what microbial life might look like
VENUS: THE BASE
Venus, the second planet from the sun, is a rocky world about the same size and mass as Earth.
However, the atmosphere is radically different from ours: It consists of 96 percent carbon dioxide and has a surface temperature of 464 °C and a pressure 92 times that on Earth.
The inhospitable planet is shrouded in clouds of sulfuric acid that make its surface impossible to glimpse.
It has been suggested in the past that Venus probably had oceans similar to Earth’s — but these would have evaporated when it underwent a runaway greenhouse effect.
The surface of Venus is a dry desert landscape, which changes periodically due to volcanic activity.
Facts and numbers
Turnaround time: 225 days
Surface: 460.2 million km²
Distance from Zon: 108.2 million km
Duration of the day: 116d 18h 0m
Ray: 6,051.8 km
Mass: 4.867 × 10^24 kg (0.815 M⊕)
Their models looked at a special feature of the dense atmosphere, namely the abundance of sulfur dioxide (SO2).
On Venus — the brightest natural object in Earth’s night sky after the moon — there are high levels of SO2 lower in the clouds, but it’s somehow “sucked out of the atmosphere” at higher elevations, the report said. scientists.
On Earth, most SO2 in the atmosphere comes from volcanic emissions.
dr. Oliver Shorttle of Cambridge’s Department of Earth Sciences and Institute of Astronomy and a co-author of the study, said: ‘If life is present, it must influence atmospheric chemistry.
“Could life be the reason SO2 levels on Venus are being reduced so much?”
Researchers used a combination of atmospheric and biochemical models to study the expected chemical reactions, given the known sources of chemical energy in Venus’ atmosphere.
The models contain a list of metabolic reactions that the life forms would carry out to obtain their ‘food’, and the waste by-products.
Scientists have used the model to see if the reduction in SO2 levels can be explained by these metabolic reactions.
They found that the reactions can result in a drop in SO2 levels, but only by producing other molecules in very large quantities that are not seen.
The results suggested a hard limit to how much life could exist on Venus without blowing apart our understanding of how chemical reactions work in planetary atmospheres.
“We looked at the sulfur-based ‘food’ available in Venus’ atmosphere — it’s not something you or I would want to eat, but it’s the main source of energy available,” Jordan said.
“If that food is being consumed by life, we should see evidence of it by specific chemicals being lost and gained into the atmosphere.
“If life were responsible for the SO2 levels we see on Venus, it would also break everything we know about Venus’ atmospheric chemistry.
“But if life isn’t responsible for what we see on Venus, it’s still a problem to be solved — there’s a lot of strange chemistry to follow up on.”
While there’s no evidence of sulphur-eating life hiding in Venus’ clouds, the researchers said their method of analyzing atmospheric signatures will be valuable when NASA’s $10 billion (£7.4 billion) James Webb Space Telescope (JWST) will begin returning images from other planetary systems later this year.
Some of the sulfur molecules in the current study are easy to spot with JWST, so learning more about our neighbor’s chemical behavior could help scientists find similar planets in the galaxy.
dr. Shorttle said, ‘To understand why some planets are alive, we need to understand why other planets are dead.
For nearly 50 years, experts have been baffled by the presence of ammonia, a colorless gas made of nitrogen and oxygen, which was tentatively detected in the atmosphere of Venus in the 1970s.
“If life could somehow sneak into the Venusian clouds, it would totally change the way we look for chemical signs of life on other planets.”
Even if Venus has no life, the researchers said their results could be useful for studying the atmospheres of similar planets in the galaxy and the eventual detection of life outside our solar system.
dr. Paul Rimmer, of Cambridge’s Department of Earth Sciences and Cavendish Laboratory, as well as a co-author of the study, said: ‘We have spent the past two years trying to explain the strange sulfur chemistry we see in the clouds of Venus.
“Life is pretty good at weird chemistry, so we explored whether there’s a way to make life a possible explanation for what we see.
Even if ‘our’ Venus is dead, it is possible that Venus-like planets in other systems harbor life.
“We can take what we’ve learned here and apply it to exoplanetary systems — this is just the beginning.”
The study is published in the journal nature communication†
CARBON DIOXIDE AND SULFURIC ACID DROPS IN THE ATMOSPHERE OF VENUS
The atmosphere of Venus is mostly carbon dioxide, with clouds of sulfuric acid droplets.
The thick atmosphere traps heat from the sun, resulting in surface temperatures over 470 °C (880 °F).
The atmosphere has many layers with different temperatures.
At the level of the clouds, about 50 km above the surface, it is about the same temperature as on the Earth’s surface.
As Venus moves forward in its orbit around the sun as it slowly spins backward on its axis, the highest level of clouds zips around the planet every four Earth days.
They are powered by hurricane-force winds at about 224 miles (360 km) per hour.
Atmospheric lightning bolts illuminate these fast-moving clouds.
Speeds in the clouds decrease with the height of the clouds, and on the surface they are estimated to be only a few miles (km) per hour.
On the ground, it would look like a very hazy, cloudy day on Earth, and the atmosphere is so heavy it’s like you’re a mile deep under water.