The planet Venus, the second planet in the solar system according to its distance from the Sun, could have harbored life for 2,000 to 3,000 years, as it met the ideal conditions (stable temperature and water) for that to happen, according to a study presented in Congress. European Planetary Science Institute (EPSC-DPS) by two members of NASA’s Goddard Institute for Space Science (GISS).
Unfortunately, Venus is today a planet reminiscent of Dante Alighieri’s seventh ring of hell.
Venus is slightly smaller than Earth and is covered in mountains and large lava plains with scorching temperatures and a heavy atmosphere composed mostly of carbon dioxide with thick clouds of sulfuric acid. But this new study suggests that the planet may once have been characterized by warm conditions and liquid water capable of supporting life. That is, until a dramatic transformation more than 700 million years ago restructured the atmosphere of Venus.
“Our hypothesis is that Venus may have had a stable climate for billions of years. It is possible that the near-global resurfacing event is responsible for its transformation from an Earth-like climate to the hellish greenhouse that we see today, ”said Michael Way of the Goddard Institute for Space Studies in a press release.
1978 Pioneer Mission
The work builds on previous research from NASA’s Pioneer Venus mission that suggested the planet once had shallow oceans of water. On this occasion, the scientists ran five computer simulations that assumed different levels of water coverage across the planet to see if a stable climate would have been able to withstand it. Three of the five scenarios assumed that Venus had a topography similar to what we see today, but with an ocean averaging 310 meters, a shallow water layer averaging 10 meters, and a small amount of water blocked in the I usually. They then compared them to a scenario that represents a planet with the topography of the Earth and a world with oceans reaching 158 meters deep.
Subsequently, the researchers simulated environmental conditions 4.2 billion years ago, 715 million years ago, and today, adapting a 3D general circulation model to account for the increase in solar radiation seen in our Sun throughout the changing weather and atmospheric compositions on Venus .
Computer simulations
According to simulations, Venus could have maintained stable temperatures between 20 and 50 ° C for about 3 billion years. Around 4 billion years ago, Venus would have cooled rapidly after its formation, resulting in an atmosphere dominated by carbon dioxide. For the next 3 billion years, the planet may have evolved like Earth and locked CO2 in silicate rocks on the planet’s surface. At some point, about 715 million years ago, researchers believe that the atmosphere may have been dominated by nitrogen with traces of CO2 and methane, just as Earth is today.
“Venus currently has almost twice the solar radiation that we have on Earth. However, in all the scenarios that we have modeled, we have found that Venus could still withstand surface temperatures susceptible to liquid water, ”clarified Way.
Dramatic event
These conditions may have remained until today if a mysterious cataclysmic event had not occurred . Between 700 and 750 million years ago, a series of events released, or “degassed”, carbon dioxide stored in the rocks of the planet. Although the exact cause is unknown, scientists believe it was likely related to volcanic activity , such as what happens when magma bubbles and releases CO2 from molten rocks into the atmosphere. If these rocks were to solidify before reaching the surface, a barrier would have been created that would prevent the gas from being reabsorbed into the rocks, causing a greenhouse effect.
“On Earth, we have some examples of large-scale degassing, for example the creation of the Siberian traps or ladders 500 million years ago that is linked to mass extinction, but nothing on this scale. It completely transformed Venus ”, concluded the expert.
How this process occurred depends on a deeper understanding of how quickly Venus initially cooled after its formation and whether it was able to condense liquid water on its surface in the first place. It is unknown whether the degassing event occurred in one event or over the course of several. All in all, the researchers say that a deeper understanding of the rocky planet is needed to answer these questions.
If they’re right, it doesn’t just mean that Venus could have supported life at some point, it means that planets like Venus, generally considered uninhabitable due to proximity to their host stars, might not be so sterile after all.
“This opens up all kinds of implications for exoplanets found in the so-called ‘Venus Zone’ , which can host liquid water and temperate climates,” Way clarifies.
Referencia: A view tothe possible habitability of ancient Venus over three billion years The Europlanet Society. The research was presented last week at the EPSC-DPS Joint Meeting 2019 in Geneva, Switzerland. https://meetingorganizer.copernicus.org/EPSC-DPS2019/EPSC-DPS2019-1846-1.pdf
