Planetary researcher Tereza Konstantinou and colleagues at the University of Cambridge examined the chemical composition of Venus’s atmosphere and found that the planet’s interior today is too dry to support oceans on its surface. I reasoned that it wasn’t. Rather, Venus is thought to have been a scorching and harsh world throughout its history.
This composite image taken by JAXA’s Akatsuki spacecraft shows Venus. Image credit: JAXA / ISAS / DARTS / Damia Bouic.
From a distance, Venus and Earth look like siblings. It is a rocky planet, about the same size as Earth.
But up close, Venus is more like its evil twin. Venus is covered in thick clouds of sulfuric acid, and its surface has an average temperature of nearly 500 degrees Celsius.
Despite these extreme conditions, astronomers have wondered for decades whether Venus once had a liquid ocean capable of supporting life, or whether some mysterious form is now hidden within its thick clouds. I have been investigating whether there are “airborne” life forms.
“Until we send a probe at the end of this decade, we won’t know if Venus could support life, or if it actually could support life,” Constantineau said.
“However, given that Venus likely did not have an ocean, it is unlikely that Venus could have supported Earth-like life that required liquid water.”
When looking for life elsewhere in the galaxy, astronomers focus on planets orbiting their host stars within the habitable zone. There, temperatures are such that liquid water can exist on the planet’s surface.
Venus provides strong constraints on where this habitable zone exists around the star.
“Despite being our closest planet, Venus is important for exoplanet science because it allows us to explore planets at the edge of the habitable zone that have evolved quite differently than us. Because it gives us a unique opportunity,” Constantinou said.
A dichotomous climate pathway for Venus is proposed. Image credit: Konstantinou others., doi: 10.1038/s41550-024-02414-5.
There are two main theories about how conditions on Venus have evolved since its formation 4.6 billion years ago.
First, surface conditions on Venus were once warm enough for liquid water to exist, but a runaway greenhouse effect caused by widespread volcanic activity has caused Venus to become increasingly hot. is.
The second theory is that Venus was born at such a high temperature that liquid water could not condense on its surface.
“Both of these theories are based on climate models, but we wanted to take a different approach based on observations of Venus’s current atmospheric chemistry,” Constantinou said.
“To keep Venus’s atmosphere stable, the chemicals that are removed from the atmosphere must also be replaced, because the interior and exterior of Venus are constantly in chemical communication with each other.”
The researchers calculated the current rate of destruction of water, carbon dioxide, and carbonyl sulfide molecules in Venus’s atmosphere, which must be repaired by volcanic gases to keep the atmosphere stable.
Volcanic activity provides a window into the interiors of rocky planets like Venus through the supply of gases into the atmosphere.
As magma rises from the mantle to the surface, it releases gases from deep within the planet.
Since the Earth’s interior is rich in water, volcanic eruptions on Earth produce mostly water vapor.
However, based on the composition of the volcanic gases needed to maintain Venus’s atmosphere, scientists have found that Venus’s volcanic gases are at most 6% water.
These dry eruptions suggest that Venus’s interior, the source of the magma that releases volcanic gases, is also dry.
By the end of this decade, NASA’s DAVINCI mission will be able to test and confirm whether Venus has always been an arid and inhospitable planet by sending a series of flybys and probes to the surface. Dew.
The results could help astronomers narrow their search for planets capable of supporting life in orbits around other stars in the galaxy.
“If Venus was habitable in the past, that means other planets we have already discovered may also be habitable,” Constantineau says.
“Instruments like NASA/ESA/CSA’s James Webb Space Telescope are ideal for studying the atmospheres of planets close to their host stars, like Venus.”
“But if Venus was never habitable, Venus-like planets elsewhere are less likely to have habitable conditions or candidates for life.
“We wanted to know that Venus was once a planet much closer to ours, so it’s sad in a way to find out that it wasn’t, but in the end it turned out that most of it was a planet closer to Earth. It would be more profitable to focus our exploration on planets that could probably support life, at least life as we know it. ”
of study Published in this month’s magazine natural astronomy.
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T. Constantinou others. The arid interior of Venus, constrained by atmospheric chemistry. Nat Astronpublished online on December 2, 2024. doi: 10.1038/s41550-024-02414-5
This article is based on a press release provided by the University of Cambridge.
Source: www.sci.news
