A moon of Jupiter concerning the dimension of Mercury doubtless has a several-miles-deep ocean underneath its icy shell, in keeping with a brand new examine.
This Jovian moon, Callisto, is the outermost of 95 circling the fuel big planet. Again within the Nineteen Nineties, NASA‘s Galileo spacecraft found one thing unusual about it: The moon appeared to react to Jupiter’s altering magnetic subject. Understanding that saltwater can conduct electrical energy, scientists suspected the world might need a layer of liquid ocean deep down.
Nevertheless it wasn’t an open-and-shut case. Callisto additionally appeared to have an ionosphere, a layer of electrically charged particles excessive in its ambiance. That meant scientists could not rule out the chance it was the ionosphere — not a subsurface ocean — inflicting the magnetic reactions.
Now researchers are extra optimistic than ever that Callisto is among the many pantheon of water worlds within the photo voltaic system. And the place there’s water, there’s the possibility for all times as we all know it.
From left, moons Ganymede, Callisto, and Io are seen orbiting Jupiter in a Hubble House Telescope picture.
Credit score: NASA / ESA / Hubble Heritage Workforce (STScI / AURA)
Callisto, the third largest moon in your complete photo voltaic system, orbits Jupiter from about 1.2 million miles away. The rocky world, found in 1610 by Italian Renaissance man Galileo Galilei, has earned a repute as essentially the most closely cratered moon in our photo voltaic system.
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The brand new proof relating to Callisto comes from a considerably shocking place: outdated information. NASA’s Galileo mission, which launched into area in 1989, was designed to review Jupiter, its moons, and its surrounding invisible magnetic bubble, referred to as the magnetosphere. The spacecraft had 35 encounters with Jupiter’s main moons, together with eight with Callisto, earlier than the mission led to 2003.
Lately, a staff of scientists took one other have a look at Galileo’s information, utilizing superior laptop fashions and statistical strategies. In contrast to prior research, the staff analyzed all of the magnetic measurements from the shut flybys of Callisto. Their findings revealed that Callisto’s ionosphere alone couldn’t clarify the magnetic reactions — and once they factored in an underground ocean, the info made extra sense. The analysis, printed within the journal AGU Advances, helps substantiate the ocean idea.
The staff predicts the ocean is locked beneath a stable ice shell that could possibly be tens to a whole bunch of miles thick. The flowing water doubtless wraps round a stable rocky core. If true, that will make Callisto an in depth sibling to Europa, one other moon of Jupiter.
Although the existence of an ocean stays inconclusive, future spacecraft measurements ought to be capable to verify as soon as and for all whether or not Callisto is hiding liquid water. NASA’s Europa Clipper and the European House Company’s JUICE, a wonky acronym for Jupiter Icy Moons Explorer, are anticipated to seize information once they make flybys. China’s deliberate Tianwen-4 mission can also observe Callisto.
After a profitable October 2024 launch, Europa Clipper has been hurtling by area. It is on schedule to make its first flyby of Mars on Feb. 27, the place it would get a gravity help to proceed its journey. The craft will not arrive at Europa till 2030. JUICE, which launched in 2023, can have a Venus flyby this August. The spacecraft is not anticipated to achieve Jupiter to start its science mission till 2031.
Whether or not the moon might harbor life is unknown, however it’s “on the list” of potential locations NASA wish to look. Not solely does it in all probability have a salty ocean, however a layer of rocks greater than 150 miles beneath the floor. Each are key situations identified for resulting in life on Earth. Oxygen and hydrogen have additionally been detected in Callisto’s extraordinarily skinny ambiance.
