There are more than 200 moons in the solar system, but none like Io, the third largest of Jupiter’s 80 moons. Io is really volcanic. In fact, it is peppered with hundreds of powerful active volcanoes under whose crust there must be something extraordinary.
That thing could be a thick, moon-level layer of molten rock — or a “subterranean magma ocean,” according to a new study published in the journal Planetary Science Journal 16 from Yoshinori Miyazaki and David Stephenson, planetary scientists at Caltech.
This potentially superheated sea of molten rock—unique in the solar system—could hold secrets, strange mechanisms for forming moons and planets, and even recipes for strange alien life. Only further scrutiny of the 2,200-mile-diameter moon will tell.
Miyazaki and Stevenson weren’t the first scientists to guess what lurks beneath Io’s potentially 20-mile-thick crust. It has been the subject of heated debate for years. But their new, peer-reviewed study of the moon’s mantle may be the most comprehensive yet.
To look beneath the surface of Io, Miyazaki and Stephenson revisited reams of data from NASA’s Galileo probe, which orbited Jupiter for eight years starting in 1995. Initial analysis of the probe’s magnetic data led to a loose consensus that Io’s mantle—the layer beneath The moon’s crust—it includes a 30-mile-thick upper layer that should be “molten or partially molten,” according to NASA.
Compare this to Earth’s mantle, as well as the mantle of every other planetary body in the solar system, which is mostly solid and composed largely of ice or superheated rock. In general, planetary scientists reading Galileo’s data assumed that Io either has an ocean of magma underground or some sort of rocky, sponge-like outer mantle submerged in magma.
A new look at the data led by Miyazaki and Stephenson concludes that it is the molten sea. They based their conclusion on estimates of mantle temperature through analysis of Io’s volcanoes, which can spew magma hundreds of miles into the moon’s sulfur dioxide atmosphere. The top of the mantle may reach temperatures of 2,800 degrees Fahrenheit.
That’s hot. But not hot enough to preserve the squishy interior. The analysis is complex, but it boils down to this: Like a pot of gravy on a stovetop, Io will need a lot of heat to stay constantly spongy in the upper mantle. without Heat enough, the broth—the spongy rock—will separate: rock at the bottom and magma at the top.
Crunching the numbers, Miyazaki and Stephenson calculated the heat from Io’s core as well as the effects of its strange, steep orbit, which corrodes the mantle, spreading heat around it, and preventing Io from permanently cooling.
They concluded that the gravy would separate. “The amount of internal heating is insufficient to maintain a high melting point,” they wrote. Hence what they think could be the highest ocean of magma.
Fortunately, we’ll know more soon. NASA’s Juno probe, which arrived around Jupiter in 2016, is scheduled to take readings of Io in 2023 and 2024 — specifically measuring the “love number,” a measure of the planet’s hardness or lack thereof. “If a large number of love is found, we can say with more certainty that a magma ocean exists beneath Io’s surface,” Miyazaki told The Daily Beast.
We already knew Io was weird. It is possible that even weirder– And this weirdness could have implications across space science. “I don’t think it significantly changes understanding of planetary formation, but it does change how we see the internal structure and thermal evolution of heated objects like Io,” David Grinspoon, a senior scientist at the Arizona-based Planetary Science Institute, told The Daily Beast.
Astrobiologists lurk in the academic shadows. Experts in how and where life might have evolved in the universe. If there is extraterrestrial life out there somewhere and it looks like life on Earth, we should expect to find it — or evidence of its extinction — on planets and moons that had or had Earth-like environments. Mars. Venus. A moon of Saturn called Enceladus.
But volcanoes, with their extreme transfers of energy, are widely considered essential components of a living ecosystem. So planets and moons with lots of volcanoes are great places to look for ET in theory, that should include Io.
However, Io too much volcanoes. So if there’s life evolving there, it’s probably very alien life Really loves the heat. “Lava tubes can create a favorable condition for microbes,” said Miyazaki.
The question, for astrobiologists, is whether a magma ocean would create more or fewer lava tubes than a magma sponge would. “I don’t have an honest answer,” said Miyazaki. “But it’s interesting to think about such implications.”
Dirk Schulz-Macuch, an astrobiologist at the Technical University of Berlin, has long advocated a comprehensive search for life on Io. The magma ocean will not spoil this research unless it is very close to the surface. The thick, gentle crust should insulate the most remote regions of the planet from drying heat, and preserve the possibility of evolution. “There seems to be quite a bit of dandruff,” Schultz-McCouch told The Daily Beast.
If anything, the possibility of a magma ocean on Io only underscores how exciting and interesting the moon is — and why it should be a prime target for future space probes, Schulz-McCouch said. “Io is a unique type of moon, very dynamic, and we shouldn’t completely ignore it.”
#infernal #lurking #Jupiters #moons