Jupiter’s Hellish Moon, Io: Volcano Epi-Center of Our Solar System –“Could Harbor Extreme Life” (Weekend Feature)




“Everyone right away tends to categorically exclude the possibility of life on Io,” said astrobiologist Dirk Schulze-Makuch at Washington State University. “Conditions on Io might have made it a friendlier habitat in the distant past. If life did ever develop on Io, there is a chance it might have survived to the present day.”

Jupiter’s Io is the volcanic epi-center of our solar system. But once you absorb the fact that the Jupiter’s innermost moon is slathered in sulfurous lava erupted from 400 active volcanoes, you might turn your attention to scattered bumps and lumps that turn out, on closer inspection, to be Io’s version of mountains.There are about 100 of them, and they don’t look anything like the low lying volcanoes.


They also don’t look like mountains on our home world. While we favor majestic ranges stretching from horizon to horizon, the mountains on Io are isolated peaks of great height that jut up out of nowhere. From space, they look rather like the blocky chips in the fancier kind of chocolate chip cookie.


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For planetary geophysicists like William McKinnon, professor of earth and planetary science at Washington University in St. Louis, the mountains of Io are an intriguing puzzle. By what process consistent with everything that is known about Io could these bizarre mountains have formed?




Since Io buries the evidence of its tectonic processes under a continually refreshed coating of lava (adding 5 inches a decade), the scientists have turned increasingly to computer simulations to solve the problem. In the May 16 online advance issue of Nature Geoscience, McKinnon and Michael T. Bland, a research space scientist at the USGS Astrogeology Science Center in Flagstaff, Ariz., publish a computer model that is able to make numerical mountains that look much like the jutting rock slabs on Io. Active volcanoes are shown in the image above; constant lava flows in NASA image below.




“The planetary community has thought for a while that Io’s mountains might be a function of the fact that it is continuously erupting lava over the entire sphere,” McKinnon said. “All that lava spewed on the surfaces pushes downward and, as it descends, there’s a space problem because Io is a sphere, so you end up with compressive forces that increase with depth.”

Was Earth once like Io? If all of this seems very alien, it is. “It’s a novel mountain-forming mechanism that we don’t see elsewhere in the solar system,” McKinnon said.”But the same kind of thing could have happened on Earth, when it was very young and entirely covered by a shallow ocean, because there was still lots of volcanism, mountains like those on Io might have burst through the ocean. They might have been the first emergent land on Earth,” McKinnon added.

So Io might be a time portal to the early Earth. But could it also harbor life?

“Life on the surface is all but impossible, but if you go down further into the rocks, it could be intriguing,” said Dirk Schulze-Makuch. “We shouldn’t categorize it as dead right away just because it’s so extreme.”

Computer models suggest Io formed in a region around Jupiter where water ice was plentiful. Io’s heat, combined with the resulting possibility of liquid water, could have made life plausible.

“There must have been quite a lot of water on Io shortly after formation, judging from the amount of water ice on Europa and Ganymede,” said Schulze-Makuch.

Jupiter’s radiation would have stripped this water from Io’s surface, perhaps within 10 million years. At this point life could have retreated underground, where water might still be abundant, and geothermal activity and sulfur compounds could provide microbes with sufficient energy to survive.

Although no organic molecules have been detected on the moon’s surface, that does not mean they do not exist underground, Schulze-Makuch said. Any organic compounds that once existed on the surface or that may today still emanate from the subsurface — which probably were naturally present in this region of space during Io’s formation — would get quickly destroyed by Jupiter’s radiation.

The many lava tubes thought to exist on Io could serve as an especially favorable environment for life, Schulze-Makuch suggested, by protecting organisms from radiation. The lava tubes also could provide thermal insulation, trapping moisture and providing nutrients such as sulfurous compounds. Microbes are common in lava tubes on Earth, from ice and volcano zones in Iceland to hot sand-floored tubes in Saudi Arabia, and lava tubes are the most plausible cave environment for life on Mars, he added.

The primordial soup that any life on Io might have originated from was likely based on water, but the solvent of choice for organisms there might have drastically changed later on as the moon transformed. Hydrogen sulfide is one choice, as it is reasonably abundant in Io’s shallow subsurface and remains liquid from negative 123 to negative 76 degrees F (-86 to -60 degrees C), falling within the environmental conditions that would prevail there. While it is not especially efficient as a solvent for ions, it does dissolve many substances, including many organic compounds. Other possibilities include sulfur dioxide and sulfuric acid.

“I’m exploring with colleagues whether sulfur compounds could work as solvents of life,” Schulze-Makuch noted. Given the wild extremes Io can swing through as it orbits Jupiter, one possible survival strategy for life in this challenging environment would be to remain dormant most of the time, only reverting back when nutrients were rich. “It’d be much easier for life to take a beating if it goes dormant regularly,” Schulze-Makuch said.

The Daily Galaxy via Washington State University and Washington University, St. Louis

Image credits: NASA’s Goddard Space Flight Center, NASA/JPL/University of Arizona


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