Jupiter’s forgotten Moon Callisto remains the Planet’s Moon

Long touted as a potential place in human history in science fiction, Jupiter’s icy moon Callisto largely remains a mystery to real-life planetary scientists. As one of Jupiter’s least studied and Saturn’s largest moons, many researchers consider it a corpse.

But a new page is emerging Journal of Geophysical Research: Planets reveals a new mystery about Callisto. The new models show that it has more molecular oxygen in its atmosphere than previous models over the decades had shown.

The American Geophysical Union says: “Earlier observations on Jupiter’s second largest moon, Callisto, found molecular oxygen in Callisto’s atmosphere.” “Scientists think that the oxygen in the atmosphere is created by Jupiter’s magnetism interacting with the moon’s ice,” says AGU.

But this new study shows that there is not enough molecular oxygen to match the observations. Thus, Callisto’s moon must be O2 in some way.

This suggests that Callisto’s source of O2 and/or calculations of molecular oxygen lifetimes should be re-examined, Shane Carberry Mogan, a postdoctoral scholar in planetary science at the University of California at Berkeley and lead author of the paper, told me by phone. and email.

“Satellites like this store ice, made up mainly of H20, whose molecular bonds are broken by incoming impacts and the influx of charged particles,” said Carberry Mogan. This hydrogen and oxygen will then recombine and form new molecules, such as H2 and O2, and sometimes even H2O2, he says.

But Callisto has never been a Candidate for life

It is very cold, there is no inner magnetosphere, and there are no signs of active cryovolcanism. Callisto retains water, however.

Life on Earth needs water and Callisto has H2O, says Carberry Mogan. But because of the cold temperatures in the outer solar system, H20 is primarily in the form of ice, with an additional portion of water vapor from the ice being released from the surface, he says.

As for the surface of Callisto?

“We hypothesize that Callisto’s surface is divided into cold, bright icy regions and relatively warm, dark non-icy or non-icy material,” the authors wrote.

Based on data from NASA’s Galileo spacecraft, it appears that Callisto’s interior is a mixture of ice and undifferentiated rock. In other words, Callisto’s interior does not have a bulk mass separation, such as a core and a mantle.

Why does Callisto get so little attention?

There are a few reasons, says Carberry Mogan. When two of NASA’s Voyager spacecraft flew by in the late 1970s, all they saw was a torn body and that was it, he says.

Jupiter’s moons Europa and Ganymede were particularly interesting, says Carberry Mogan. “Callisto is in this region of all other exotic bodies, and it’s such a complex moon that it’s hard to explain,” he said.

Two future missions, NASA’s Europa Clipper, to Jupiter and the European Space Agency’s Jupiter Icy Moons Explorer will visit the Jovian system. JUICE will fly by Callisto more than twenty times, and the Europa Clipper will fly by the icy moon a few times as well.

But understanding Callisto is important for the study of other large, icy moons, Carberry Mogan said. And it will be useful in interpreting the data we eventually get from JUICE and the Europa Clipper, he says.

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