Ganymede has become a place that we are paying a lot of attention to lately. And is not for less. Scientists have just detected water vapor in the atmosphere of Jupiter’s largest moon. While Ganymede has been known for years to harbor water, it was previously believed that most of it had frozen to the moon’s surface or was potentially trapped as a liquid under massive ice sheets. Now, after looking at the last two decades of data from the NASA / ESAm Hubble Space Telescope, scientists have announced the discovery of evidence of water vapor in Ganymede’s atmosphere for the first time in history. That is, in this exciting new discovery, scientists have found evidence of the result of sublimation of ice from the moon’s surface.
“Until now only molecular oxygen had been observed,” explained Lorenz Roth of the KTH Royal Institute of Technology in a press release. “This occurs when charged particles erode the surface of the ice. The water vapor we have measured is caused by sublimation of ice caused by the thermal escape of water vapor from hot and icy regions.”
Previous research suggested that the ice on Ganymede’s surface could go from solid directly to gas, jumping into a liquid form, so that water vapor could become part of the giant moon’s thin atmosphere. However , evidence for this water has proven elusive, until now.
By examining data from Hubble, which captured the first ultraviolet images of Ganymede in 1998, astronomers were able to measure the amount of atomic oxygen in Ganymede’s atmosphere and found that there is hardly any atomic oxygen (that is, individual oxygen atoms). , which suggests that there must be another explanation for the UV signals above.
It turns out that water vapor could cause this feature, and the location of this difference would be exactly where the water vapor would be if it were degassed at the moon’s equator. This indicates that instead of coming from the subsurface ocean, water vapor, not just oxygen, may be escaping from warmer areas of the moon by turning from a solid to a gas.
These enlightening findings contribute to scientists’ understanding of Ganymede’s atmosphere and add to the excitement surrounding ESA’s planned JUICE (JUpiter ICy Moons Explorer) mission to launch in 2022 and reach Jupiter in 2029. . in this mission, JUICE will pass the least three years studying the planet and three of its largest moons, with special emphasis on the moon in question, Ganymede.
“Our results can provide the JUICE instrument teams with valuable information that can be used to refine their observation plans to optimize the use of the spacecraft,” said Roth.
Understanding the Jovian system and unraveling its history, from its origin to the possible appearance of habitable environments, will provide us with a better understanding of how gas giant planets and their satellites form and evolve.
Referencia: “A sublimated water atmosphere on Ganymede detected from Hubble Space Telescope observations” by Lorenz Roth, Nickolay Ivchenko, G. Randall Gladstone, Joachim Saur, Denis Grodent, Bertrand Bonfond, Philippa M. Molyneux and Kurt D. Retherford, 26 July 2021, Nature Astronomy.
DOI: 10.1038/s41550-021-01426-9
