Venus’s reputation as a cautionary tale of Earth’s deterioration may be somewhat exaggerated.
We thought Venus might once have been habitable, with oceans of liquid water sparkling on its surface, before it became the toxic hellscape we know today. Earth’s so-called sister planet may not have had liquid oceans, according to a new study. This was not possible even when there was water.
In fact, analysis of the planet’s atmosphere shows that its interior and exterior have always been drier than bone.
“By calculating the current rate of atmospheric destruction of water, carbon dioxide and carbonyl sulfide that must be restored by volcanism to maintain atmospheric stability, we show that Venus’s interior is dry.” write a team Led by astronomer Tereza Constantinou of the University of Cambridge, England.
“The dry interior is consistent with Venus having had a dry surface for a long time after it ended its magma ocean era and desiccated, so the volcanic resupply of Venus’s atmosphere indicates that the planet has never been habitable for liquid-water. “
Venus has many similarities to Earth. They are similar in size, have similar mass and density, and have similar mineral composition. But the way it would make a big difference to habitability as we know it is very different. The average surface temperature is around 465 degrees Celsius (870 degrees Fahrenheit), and atmospheric pressure is 92 times that at sea level.
And that’s not into a suffocating, highly toxic cloud of carbon dioxide that pours out sulfuric acid. It’s literally a hot, unlivable mess. However, Venus’ similarity to Earth and its location at the edge of the solar system’s habitable zone make it an interesting research prospect. Have you ever been able to live there? could do it Is it habitable?
If the answer to both questions is “yes,” it could tell us about the evolutionary changes that Earth may one day undergo and the prospects for life elsewhere in the galaxy.
“Venus provides a natural laboratory for studying how habitability, or lack of habitability, evolves. This is applicable not only to habitable systems, but also to exoplanets. If Venus was habitable in the past, this means we could already be habitable. It turns out that other planets may be habitable,” Constantinou told ScienceAlert.
“But if Venus was never habitable, it is unlikely that planets like Venus would be candidates for habitable conditions or life elsewhere.”
frameborder=”0″allow=”Accelerometer; autoplay; Write clipboard; encrypted media; gyroscope; picture within picture; Web sharing”referrerpolicy=”strict-origin-when-cross-origin”allowfullscreen>
To study Venus’ water history, Konstantinou and her colleagues looked at how quickly water, carbon dioxide, and carbon sulfide in Venus’ atmosphere break down. Maintaining a stable atmosphere requires constant replenishment of these molecules through volcanic gas emissions.
On Earth, the volcanic gases entering the atmosphere are dominated by vapor because the Earth’s interior is so humid. Researchers have discovered that Venus’ volcanic gases consist of up to 6% vapor. From this, they deduced that Venus’ interior is very dry and that the planet cannot sustain liquid oceans.
This is consistent with surface observations showing a lack of water erosion compared to places like Earth or Mars. This is consistent with previous research that used modeling to study Venus’ early atmosphere.
This does not mean that water could not have existed on Venus. A recent study of Martian meteorites suggests that Earth and Mars may have experienced similar water transfers early in solar system history, suggesting that these transfer mechanisms were relatively ubiquitous. However, water transfer is not the same as water retention.
“If Venus once had a large water reservoir, our study suggests that it could never have condensed into a water ocean. Instead, early Venus may have had an atmosphere like this: lots of steam“, explained Constantine.
“Over billions of years, this atmospheric vapor would have undergone photolysis, splitting water molecules into hydrogen and oxygen, with the lighter hydrogen gradually escaping into space. This process gave Venus the dry atmosphere we observe today.”
If so, it means that exoplanets with atmospheres similar to Venus could be ruled out in the search for life outside our solar system, at least for now. If we discover microbes living their best lives in the clouds of Venus, we could take another look at that prospect.
“The lack of oceans on Venus in the past means that Venus never experienced the conditions necessary to develop and sustain Earth-like life. Any potential life in the Venusian atmosphere would have originated and evolved under completely different conditions, most likely sulfuric acid.” They must have adapted to survive in the clouds – there is so much life we don’t know about yet.” Constantinou told ScienceAlert.
“This possibility is exciting because it broadens the scope of astrobiology to include life forms that thrive in extreme, unconventional environments.”
This study was published in: nature astronomy.
