Thursday, September 23

Ganymede’s atmosphere contains water, a potential sign of life

Ganymede's atmosphere contains water, a potential sign of life

Ganymede’s atmosphere contains water, a potential sign of life

For the first time, NASA astronomers have detected water vapor in the atmosphere of Ganymede, one of Jupiter’s four moons. The surface temperature of this moon varies greatly throughout the day: around noon, near the equator, it can get hot enough that the icy surface releases small amounts of water molecules.

And where there is water there can be life, although by itself it is not enough: it would also need carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur, the six elements constitute 98% of the living matter on Earth. Ganymede It is located more than 600 million kilometers from our planet.

To make the discovery, scientists have intertwined new observations and previous data provided by the Hubble Space Telescope. The thermal water vapor evasion of Ganymede’s icy surface has been verified after decades of observations: scientists have summarized their work and presented their conclusions in a study recently published in the journal Nature Astronomy.

Ganymede: the giant satellite and its mysteries

What was known so far about this moon of Jupiter? For example, that Ganymede is the largest natural satellite of the gaseous planet and even of the entire solar system. At the same time, it is the only one that has a magnetic field, a detail by no means less. Said magnetic field would have originated from convection movements inside the cast iron core.

Its diameter reaches 5,268 kilometers, although it represents less than half its mass. About 30% of the satellite is made up of regions filled with impact craters, which were formed about 4 billion years ago. Other areas with clear terrain would be the product of tectonic activity caused by tidal warming.

According to a Press release from NASA, previous studies have suggested that Ganymede would contain more water than all the oceans on Earth. However, the extreme cold causes the water to freeze on the surface: the huge ocean of Jupiter’s moon would be hidden approximately 100 miles below the crust of the satellite. Consequently, the steam from Water discovered would not be linked to the evaporation of this ocean.

Related topic: In search of the secrets of Jupiter.

Towards Jupiter and its moons

Meanwhile, the discovery is also of central importance to ESA, the European space agency. According to a release, it is expected that around 2022 the mission will be underway JUICE, intended for detailed observations of Jupiter and three of its largest moons. Ganymede is a priority target, depending on its characteristics and the possibility of harboring life.

The European mission, which would reach Jupiter in 2029, will search Ganymede the information necessary to try to understand the evolution of the frozen worlds in the universe, as well as more details regarding the possible presence of some form of life. It will also focus on magnetic interactions and plasma that occur between Ganymede, Jupiter and their surroundings: specialists believe that they are unique and that they could provide valuable data.


A sublimated water atmosphere on Ganymede detected from Hubble Space Telescope observations. Roth, L., Ivchenko, N., Gladstone, G.R. et al. Nature Astronomy (2021).DOI:

Video: Astronomers have used new and archival data sets from NASA’s Hubble Space Telescope to discover evidence of water vapor in the atmosphere of Ganymede, one of Jupiter’s moons. Vapor is present due to thermal excitation of water molecules on the icy surface of the satellite. Credit: NASA’s Goddard Space Flight Center.

Photo: artistic recreation of the image of Ganymede. Credit: ESA / Hubble, M. Garlick, B. Jónsson.

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