Jupiter’s moon Callisto has a thousand times more oxygen than it should, and scientists can’t explain it

2023-09-18 12:54:15

Jupiter’s four largest moons are, in addition to being large, some of the most attractive worlds in the Solar System. There we have IO, dotted with its more than 400 active volcanoes, or Europa, with its gigantic underground ocean that many believe hides strange forms of life. Or Ganymede, the largest moon in our planetary system, or Callisto itself, the object with the largest number of craters in the entire Solar System.

But Callisto also harbors another mystery, one that scientists have long tried, unsuccessfully, to explain: its dense atmosphere contains a surprisingly high amount of oxygen, and no one knows for sure why. This excess is assumed to have something to do with Jupiter’s powerful magnetosphere, which could be spewing water, hydrogen and oxygen molecules from the moon’s surface into its atmosphere. But the latest data has shown that it is not.

The data doesn’t lie

To prove it, in fact, Shane Carberry Mogan, from the University of California at Berkeley, led a team of researchers, did the numbers and discovered that Jupiter’s magnetism is not enough to explain the amount of oxygen detected in the observations. The work has just been published in ‘JGR Planets‘.

“There is a huge discrepancy,” explains Carberry Mogan. “Our data were off by two, even three orders of magnitude.” Which means that there is between 100 and 1,000 times more molecular oxygen in Callisto’s atmosphere than would be expected if Jupiter’s magnetosphere were solely responsible.

The presence of oxygen on this strange world could put Callisto on the list of candidates in the Solar System to host life, but researchers believe that, despite everything, this moon of Jupiter is too cold for life as it exists. we know. Despite this, this oxygen could be very useful for future generations of explorers to use as fuel or life support in their deep space missions.

Looking for an explanation

Be that as it may, it is not clear what is happening on Callisto to produce so much oxygen, but researchers will further study the processes acting on the surface to find an explanation.

“The most enigmatic feature of Calisto is probably its surface,” says Carberry Mogan. “It’s supposed to be an icy body, but when you look at it, what you see is mainly a dark surface, with a depth of between millimeters and kilometers.”

The question of whether there is more rock or more ice on Callisto’s surface remains a matter of debate. The predominant dark material, in fact, could also be rich in ice, and that could be the source of the mysterious amount of atmospheric oxygen. Researchers hope that, to verify this, the next robotic missions Juice, from ESA, or Europa Clipper, from NASA, can get close enough to clarify the mystery.