Hellish Venus Might Have Been Habitable for Billions of Years

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Tom Kalbfus

What if Venus had life for billons of years before Earth even developed life? This could matter if there were ancient artifacts left by the Venusians.

Hellish Venus Might Have Been Habitable for Billions of Years

A team of astronomers think the torrid and toxic world was once a cozy home for potential life

By Shannon Hall on August 10, 2016


Maat Mons is displayed in this three-dimensional perspective view of the surface of Venus. Credit: NASA/JPL

Venus is—without a doubt—Earth’s toxic sibling. Although both worlds are similar in size and density, our planetary neighbor has temperatures so high they can melt lead, winds that whip around it some 60 times faster than the planet itself rotates and an atmosphere that slams down with more than 90 times the pressure found on Earth’s atmosphere. But there have been a few tantalizing hints that billions of years ago Venus might have been more akin to Earth’s twin. In addition to their comparable sizes, the worlds also formed close together, which suggests that they are made out of the same bulk of materials. The big difference is their proximity to the sun. Because Venus is roughly 41 million kilometers closer, it receives twice as much sunlight as Earth. But a few billion years ago a slightly fainter sun might have allowed for a relatively cool Venus, one where liquid water could have pooled in vast oceans that were friendly to life.

A new study recently accepted in Geophysical Research Letters suggests that not only was Venus habitable in the distant past, it could have remained habitable for billions of years. Michael Way from NASA’s Goddard Institute for Space Studies and his colleagues applied the first three-dimensional climate model—the same computer simulations used to predict human-caused climate change on Earth—to early Venus. Because previous research only looked at one-dimensional climate models on Venus (which consider incoming and outgoing radiation but do not visualize the complexities, like clouds, within an atmosphere), the results are a huge step forward compared with previous studies, scientists say. “There's a real difference between a back-of-the-envelope calculation and actually plugging it into a more sophisticated model,” says Jason Barnes, an astronomer from the University of Idaho, who was not involved in the study.

The team first simulated how the Venusian climate might have looked 2.9 billion years ago. Such an ancient date required the researchers to make a few educated guesses about the early planet, such as assuming it had a shallow ocean just 10 percent the volume of that on Earth today. But the results were clear—2.9 billion years ago the second rock from the sun could have had a balmy Earth-like temperature that hovered around 11 degrees Celsius. The team then ran the model for a later Venus some 715 million years ago and found that even under the sun’s heightened heat, the planet would have warmed by only 4 degrees Celsius since that earlier time. Such a slight increase in temperature would have allowed the planet’s liquid ocean to persist for billions of years.

What allowed Venus to stay wet for so long? According to the models, clouds played a key role. They likely piled up on the dayside of the planet, acting as a bright shield that reflects incoming sunlight, and never formed on the nightside, letting heat radiate off into space. “To me the real takeaway message is that Venus could have been habitable for a significant period of time, and time is one of the key ingredients to being able to originate life on a planet,” says Lori Glaze, an astronomer at NASA Goddard Space Flight Center who was not involved in the study. This suggestion adds a new element to the question of habitability: time. “Habitability is not something that's static,” says David Grinspoon, an astronomer from the Planetary Science Institute and a co-author of the paper. “It's not just a question of a point in space, it's a point in space and time and how long a planet could potentially retain oceans, and if that’s long enough to be considered a good candidate to have had an origin and evolution of life.”

Those cool conditions, however, depend on whether Venus looked the same in its youth as it does today—although the researchers added an ocean, they kept Venus’s present-day topography intact—and whether it has always spun as slowly as it does now, taking 243 Earth days to complete a single rotation. Because the answers to both questions are fairly uncertain, the research team also modeled what Venus’s climate would have looked like 2.9 billion years ago if it had an Earth-like topography or spun at a slightly faster pace. The differences were huge. With mountain ranges and ocean basins similar to Earth’s, the temperature was 12 degrees warmer than with Venus’s topography. And if the rotation rate was 16 Earth days, the temperature skyrocketed 45 degrees higher than the level with its current rotation rate. The cloud pattern that kept the climate cool only formed if the planet was rotating slugglishly.

This result has vast implications for the world of exoplanets. “The community should be careful about ignoring worlds that are very close to their stars, like Venus-type worlds,” Way says. If a few key characteristics such as an exoplanet’s topography and rotation rate are just right, then the inner edge of the habitable zone—the region in a solar system where conditions conducive to life can arise—will be closer to the host star than is usually thought. The finding is especially important given that these close-in worlds are much easier to observe and characterize than other types of planets. The much-anticipated James Webb Space Telescope—often referred to as Hubble’s successor—for example, will likely only study worlds that hug their host stars, making observations of planets with wider orbits like Mars or even Earth out of the question. Or as Ravi Kopparapu, an astronomer at The Pennsylvania State University puts it: “The closest to Earth we can get with the James Webb Space Telescope is Venus around cool stars.”

But Glaze could not contain her excitement about the latest study because of the light it sheds on a rock back home. “Venus is the planet next door, the sister next door, and it's so surprising how little we know,” she says. “We know Mars so much better than we do Venus. Those [plus Earth] are our three terrestrial planets in our own backyard. If we don't understand those three planets and what makes them the same and what makes them different, we're going to be hard-pressed to interpret the new planets that we're discovering outside our own solar system.” Luckily, there are two Venus missions currently in competition for potential flight: One is a geophysical mission, which would map the planet in higher resolution than before. The other is one led by Glaze herself that would measure the makeup of the Venusian atmosphere and even return samples to Earth. Both could shed light on what Venus looked like in the past. “There is still more important data that we need to collect in order to put tighter constraints on these models, and we have the ability to collect those data now. We just need the missions,” Glaze says.
So theoretically what are the odds both Mars and Venus were inhabitable?
Does this mean the Earth was terraformed and then colonised following whatever events left both Venus and Mars uninhabitable?
Or is this evidence that all three worlds have evidence they were all terraformed but only Earth remains inhabitable?
Hopeless said:
So theoretically what are the odds both Mars and Venus were inhabitable?
Does this mean the Earth was terraformed and then colonised following whatever events left both Venus and Mars uninhabitable?
Or is this evidence that all three worlds have evidence they were all terraformed but only Earth remains inhabitable?
There was not much on Earth more than a billion years ago! There were no plants on land, single-celled organisms in the ocean, the land was a desert, no vegetation, when it rained the water just washed right into the ocean. The atmosphere had little oxygen in it, maybe the high carbon-dioxide content of the atmosphere kept the Earth from being a frozen ball of ice. Mars could have had a thicker atmosphere than the Earth, hence more greenhouse effect. If Venus had a higher oxygen content, there would have been less greenhouse effect. Venus could have been quite a bit warmer than Earth is today and still have liquid oceans. Remember that water boils at 100 degrees Celsius, and at higher temperatures at higher pressures. What if a Civilization developed on Venus, what if they explored the stars, and then the died? They could have left artifacts in our Solar System, that humans might later exploit.
Reading about this, the reports say Venus may have had water in its atmosphere but during that time it was a molten ball. The time when the planet cooled enough to form oceans and begin the creation of the very beginning of life and when the water in the atmosphere was breaking down to disperse into space would have been very brief. I believe Mars would have suffered such a brief moment too before it's atmosphere left. Earth is the right size in the right location. If Venus was in the third orbit it may have become viable where the smaller Mars would not.

We should be very grateful so many things worked JUST right. Remember too everything worked up to a short time ago in Earth's history when humanity was almost at the minimum population limit to continue. How many billions or hundreds of billions of worlds may have just missed having intelligent life for the same reasons?

On a similar note to this thread, there was a report saying we may actually be unique because many star systems are still young and life take billions of years to develop to our stage. We could be in a galaxy that is still evolving higher life and any intelligent life capable of beaming signals could be so far away, it will take years or tens of thousands of years.
In this alternate timeline, the asteroid belt is the remains of a formerly inhabitable planet.

So you would have had four.
There was a scifi story I read a looong time ago in which the belt was an inhabited planet. Wish I could remember the details. Some of the inhabitants exist in the 'modern' times of the story.
Or you could just post a link to the original article on Scientific American instead of just copying the entirety of copyrighted articles... (and not even crediting the original source).


EDIT: And according to the rights and permissions link at the bottom of that page, you're not even allowed to copy the article on another website. You really need to stop being so cavalier with other people's IP.
This post just got reported. Copyright violation. The original post just got lifted from another website, in violation of the remote site's terms and conditions against wholesale copying.

Report reason: Warez
Reported by **************************** « 2016-08-10 6:15 pm
This is an article from Scientific American, copied in its entirety without credit.
They've got a "rights and permissions" link at the bottom of the original article at http://www.scientificamerican.com/artic ... -of-years/ which explicitly says that you can't just copy the whole thing wholesale and put it on a website.

Tom, I'm afraid this thread's going to have to be shut down and removed.

And there I was, hoping I'd go a day without somebody reporting something. Come on, where's the beach, no braid on my shoulder?
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