The results paint a rather depressing result as far as habitability is concerned: At least two thirds of the simulated planets build a crust that is too buoyant to sink. But one plate will never subduct below another to remove excess carbon dioxide or form the volcanoes that spew more carbon dioxide into the atmosphere. As such, the planet will not be able to regulate its own temperature and will easily escalate into a world that resembles a snowball or a sauna.
Just think back 2. One of those uncertainties, Foley notes, is geologists still argue over how plate tectonics ignited on Earth and what continues to drive it today.
The issue is that even if a plate is dense enough to sink into the mantle, the lithosphere—the strong and rigid outer shell of the planet—has to crack first. But what causes the lithosphere to crack is hotly debated in the field.
Unterborn sidestepped this complication by looking for planets that might be able to undergo plate tectonics for billions of years—should it begin in the first place. Foley agrees that it is a clever workaround, and Unterborn argues that it is more interesting from a scientific point of view because we are more likely to find life where it has evolved over billions of years.
But the assumption plate tectonics magically begins does show that even the proper elemental cocktail does not guarantee a shifting and rumbling surface. Still, Unterborn argues it does maximize our chances of finding plate tectonics and therefore life. Just last week Foley, Unterborn and colleagues submitted a proposal to the NASA Astrobiology Institute to further assess how materials of different compositions react under high pressures and temperatures.
That would allow them to paint a more accurate picture and even explore how changing the composition might crack the lithosphere—the other important criterion for kick-starting plate tectonics.
Shannon Hall is an award-winning freelance science journalist based in the Rocky Mountains. She specializes in writing about astronomy, geology and the environment. Credit: Nick Higgins. Already a subscriber? Sign in. Thanks for reading Scientific American. If the scientists' interpretation — laid out in a study published online today Sept.
An active system of plate tectonics could also explain two puzzling facts about Europa, Kattenhorn said: 1 why its surface is so young less than 90 million years, as estimated by meteorite-impact rates , and 2 how the moon accommodates the creation of new ice on its shell, which has been observed previously. Europa isn't getting any bigger, so some process must be balancing out the production of new material. He and Prokter said Europa likely has a system of cold, brittle plates moving around above convecting warmer ice.
The mechanisms behind Europan plate tectonics are unclear at the moment, Kattenhorn said, stressing the need for modeling work. But tidal heating generated by the tug of Jupiter's immense gravity, the same phenomenon that keeps Europa's interior ocean from freezing up, may be one of the ultimate drivers, he added.
Some scientists think plate tectonics were essential to the rise of life on Earth. For example, the idea goes, the movement of plates replenishes nutrients and helps stabilize the planet's climate by recycling carbon.
So it's natural to wonder if Europan plate tectonics may make the icy moon more habitable for simple lifeforms, Selvans wrote. Europa's ice shell is thought to be 12 to 19 miles 20 to 30 kilometers thick, and subducting plates likely dive down only a mile so, Kattenhorn said.
Age isn't everything, though. Just like Earth, Venus has its own ridges, faults and possibly active volcanoes. A study argued that Venus owes much of its topography to prehistoric mantle plumes. These are columns of molten rock that sometimes reach a planet's crust. When they do, they often generate a "hot spot" of volcanic activity. Here on Earth, the lava released by mantle plumes created the Hawaiian Islands as well as Iceland. In theory, the volcanic material unleashed by hot spots could explain the presence of coronae : large, oval-shaped structures found on Venus' surface.
The plumes may have even led to the formation of unorthodox subduction zones around coronae rims. Not exactly plate tectonics, but still pretty neat. Some scientists think the existence of plate tectonics could be a prerequisite for life. As we've discussed, the plates tend to promote volcanic eruptions, which release carbon dioxide into the atmosphere. Such emissions help keep Earth's temperature nice and stable.
And that's just one of the benefits they provide to organisms. Who knows? Earth is the only planet known to harbor life. Maybe its abnormal tectonic makeup is one of the reasons why. Sign up for our Newsletter! Mobile Newsletter banner close. Mobile Newsletter chat close. Mobile Newsletter chat dots. Mobile Newsletter chat avatar. Mobile Newsletter chat subscribe. The Solar System. The largest canyon in the solar system, Valles Marineris, cuts a wide swath across Mars and extends more than 1, miles 3, kilometers long and miles kilometers across.
Could it have been created by tectonic plates? Now That's Interesting.
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