Given the diversity and complexity of endogenous and extrinsic processes that contribute to the maintenance of habitable conditions over geological and biological timescales, it is unclear how rocky planets become habitable and their status. Fully understanding how it is maintained is a fundamental challenge for planetary scientists and astrobiologists. In the face of this challenge, it is essential to exploit the full range of atmospheric evolution data for rocky planets within the solar system. Although Venus represents an apparent fringe member of planetary habitability, its contribution to understanding the prevalence of long-term temperate surface conditions in large rocky worlds remains poorly recognized. Upcoming missions to Venus, including NASA's VERITAS and DAVINCI, and ESA's EnVision mission, will begin to crystallize this understanding.
Kane and Byrne describe Venus as an anchor point where planetary scientists can better understand the conditions that prevent life on exoplanets. Image credit: Kane & Byrne, doi: 10.1038/s41550-024-02228-5.
“We often assume that Earth is a model of habitability, but when we consider this planet in isolation, we don’t know where the boundaries and limits are. Venus gives us that. '' said Dr. Stephen Cain, an astrophysicist at the University of California, Riverside.
“Although they also feature a pressure cooker-like atmosphere that could flatten humans in an instant, Earth and Venus share some similarities.”
“They have roughly the same mass and radius. Given their proximity to the planet, it’s natural to wonder why Earth looked so different.”
Many scientists believe that solar flux, the amount of energy Venus receives from the sun, caused a runaway greenhouse effect that doomed Earth.
“If Earth receives 100% of the solar energy, Venus collects 191%. Many people think that’s why Venus looks different,” Dr. Kane said.
“But wait a minute. Venus doesn’t have a moon, but that gives Earth something like ocean tides and affects the amount of water here.”
In addition to some of the known differences, more NASA missions to Venus will also clarify some of the unknowns.
Planetary scientists have no idea how big its core is, how it arrived at its current relatively slow rotational speed, how its magnetic field has changed over time, or the chemistry of its lower atmosphere. i don’t know.
“Venus has no detectable magnetic field. That may be related to the size of its core,” Dr. Kane said.
“The size of the core also gives us information about how the planet cools. Earth has a mantle, and heat circulates through its core. What’s going on inside Venus? I don’t know.”
“The interior of a rocky planet also influences its atmosphere. That is the case for Earth, and our atmosphere is primarily the result of volcanic gas emissions.”
Schematic cross-section of Earth and Venus. Major internal and atmospheric components are shown to scale. Image credit: Kane & Byrne, doi: 10.1038/s41550-024-02228-5.
NASA is planning two missions to Venus (DAVINCI and VERITAS) for the end of this decade, and Dr. Cain is supporting both.
The DAVINCI mission will explore the acid-filled atmosphere and measure noble gases and other chemical elements.
“DAVINCI measures the atmosphere from top to bottom. This is extremely useful for building new climate models and predicting this type of atmosphere elsewhere, including on Earth, as the amount of carbon dioxide continues to increase. ,” Dr. Kane said.
Although the Veritas mission will not land on the surface, it will allow scientists to reconstruct detailed 3D terrain, which could reveal whether the planet has active plate tectonics or volcanoes.
“Currently, our global map is very incomplete. Understanding how active a surface is and understanding how it has changed over time are very different. We need both types of information,” Dr. Kane said.
Ultimately, Dr. Kane and his co-author, Dr. Paul Byrne of Washington University in St. Louis, advocate such a mission to Venus for two main reasons.
One is that with better data, we can use Venus to confirm that our inferences about life on distant planets are correct.
“The somber thing about searching for life elsewhere in the universe is that we will never have in-situ data on exoplanets. We will never go there, land on them, or measure them directly. I don’t intend to,” Dr. Kane said.
“If we think there is life on the surface of another planet, we may never realize we are wrong and end up dreaming of a planet without life.” I guess.”
“We can only get it right by understanding the Earth-sized planets we can visit. Venus gives us that chance.”
Another reason to study Venus is that it can predict what Earth’s future will be.
“One of the main reasons we study Venus is because of our sacred duty as stewards of this planet to protect its future,” Dr. Kane said.
“My hope is that by studying how Venus came to be today, we can learn lessons from it, especially if it had a benign past that is now in ruins. The question is when and how.”
of review paper It was published in the magazine natural astronomy.
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Stephen R. Cain and Paul K. Byrne. 2024. Venus as an anchor point for planetary habitability. Nat Astron 8, 417-424; doi: 10.1038/s41550-024-02228-5
Source: www.sci.news
