There are over 200 moons in the solar system, but none quite like Io, the third largest of Jupiter’s 80 moons. Io is really, really volcanic. In fact, it’s dotted with so many hundreds of mighty active volcanoes that there must be something unusual beneath its crust.
According to a new study published in the Journal of Planetary Science Nov. 16 by Yoshinori Miyazaki and David Stevenson, planetary scientists at the California Institute of Technology.
This possible super-hot sea of molten rock – which is unique in the solar system – could harbor secrets, strange mechanisms for forming moons and planets, and even recipes for exotic extraterrestrial life. Only a closer look at the 2,200 mile diameter moon will tell.
Miyazaki and Stevenson aren’t the first scientists to make an educated guess about what lies beneath Io’s potentially 20-mile-thick rocky crust. This has been the subject of heated debate for years. But their new peer-reviewed study of the moon’s mantle may be the most thorough yet.
To look beneath Io’s surface, Miyazaki and Stevenson revisited reams of data from NASA’s Galileo probe, which orbited Jupiter for eight years beginning in 1995. Initial analysis of the probe’s magnetic data led to a loose consensus that Io’s mantle, the layer beneath the lunar crust — includes an upper layer 30 miles thick that should be “melted or partially melted,” according to NASA.
Compare that to the Earth’s own mantle, as well as the mantles of all other planetary bodies in the solar system, which are mostly solid and made up largely of ice or superheated rock. Generally speaking, planetary scientists reading the Galileo data assumed that Io had either an ocean of subterranean magma or some sort of rocky, sponge-like outer mantle soaked in magma.
A fresh look at the data leads Miyazaki and Stevenson to conclude that it is the molten sea. They based their conclusion on mantle temperature estimates via analysis of Io’s volcanoes, which can spew magma hundreds of miles into the moon’s sulfur dioxide atmosphere. The top of the mantle can reach 2,800 degrees Fahrenheit.
It’s hot. But not warm enough to maintain a spongy interior. The analysis is complicated, but it boils down to this: like a saucepan on a stove, Io would need a lot of heat to stay constantly spongy in its upper mantle. Without enough heat, the sauce – uh, the squishy rock – would separate: rock down, magma up.
Miyazaki and Stevenson crunched the numbers, calculating the heat of Io’s core as well as the effects of its odd, highly elliptical orbit, which laps the mantle, spreading heat and preventing Io from cooling permanently.
They concluded that the sauce would separate. “The amount of internal heating is insufficient to maintain a high degree of fusion,” they wrote. Hence what they believe to be an ocean of magma at the top.
Fortunately, we will know more soon. NASA’s Juno probe, which arrived around Jupiter in 2016, is expected to take measurements of Io in 2023 and 2024, specifically measuring the ‘love number’, a gauge of stiffness or lack thereof. of a planet. “If a large number of loves are found, we can say with more certainty that an ocean of magma exists beneath the surface of Io,” Miyazaki told The Daily Beast.
We already knew that Io is weird. It is possible that it is even weirder— and that weirdness could have implications in space science. “I don’t think it changes the understanding of planetary formation much, but it does change how we perceive the internal structure and thermal evolution of tidal-heated bodies like Io,” said David Grinspoon, senior scientist at the Planetary Science Institute, based in Arizona. told The Daily Beast.
Astrobiologists hide in the academic shadow. Experts on how and where life might evolve in the universe. If there is extraterrestrial life out there and it looks like terrestrial life, we should expect to find it – or evidence of its extinction – on planets and moons that have, or had, Earth-like environments. March. Venus. A moon of Saturn called Enceladus.
But volcanoes, with their extreme energy transfers, are widely considered key components of a living ecosystem. So planets and moons with lots of volcanoes are great places to look for ET. In theory, this should include Io.
However, Io might have too volcanoes. So if there’s life going on there, it’s probably some very strange life going on. really like the heat. “The lava tubes could create a favorable condition for microbes,” Miyazaki said.
The question for astrobiologists is whether an ocean of magma would create more or fewer lava tubes than a sponge of magma. “I don’t have an explicit answer,” Miyazaki said. “But it’s interesting to think about such implications.”
Dirk Schulze-Makuch, an astrobiologist at the Technical University of Berlin, has long advocated a thorough search for life on Io. An ocean of magma would only spoil this search if it was really close to the surface. A nice, thick crust should insulate the planet’s outermost regions from scouring heat and preserve evolutionary potential. “There seems to be quite a bit of a crust,” Schulze-Makuch told The Daily Beast.
If anything, the possibility of an ocean of magma on Io underscores just how interesting and exciting the moon is and why it should be a prime target for future space probes, Schulze-Makuch said. “Io is a unique type of moon, very dynamic, and we shouldn’t rule it out entirely.”
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