New research has shown that in fact, there is much more water vapor in Europa's atmosphere than was previously thought, and it is probably not associated with geysers gushing out from under the ice.
An international team of researchers analyzed data obtained in previous years with the Hubble Space Telescope and for the first time found evidence of the persistent presence of water vapor in the atmosphere of Europa, Jupiter’s icy moon. Scientists have been working on this research since 2013 when they detected geysers on the surface of Europa.
Hubble Finds Persistent Water Vapor on Jupiter’s Moon Europa
Geysers on Europa
The geysers on Europa turned out to be similar to geysers on Earth, but in size, they are much larger than those here. Earlier, it was estimated that the height of such fountains can reach 90 km. Calculations also showed that these geysers fill the atmosphere with water droplets, but the total volume of such water is negligible. It is only one billionth of the volume of water vapor present in Earth’s atmosphere.
More water vapor than anticipated
However, new research has shown that in fact, there is much more water vapor in Europa’s atmosphere than was previously thought, and it is probably not associated with geysers gushing out from under the ice. Scientists came to this conclusion after analyzing Hubble data obtained from 1999 to 2015. The analysis showed that water vapor is constantly present in the atmosphere of Europe.
At the same time, astronomers received a new riddle. Hubble’s data indicate that water vapor is present in the atmosphere only in one hemisphere of the icy moon of Jupiter – on that part of it, which is always opposite to the direction of motion in orbit. The reason for this asymmetry has not yet been established.
Water vapor on Ganymed
We add that earlier, astrophysicists from Sweden discovered the presence of water vapor in the atmosphere of another satellite of Jupiter – Ganymede. It was also made based on the study of archival data from the Hubble telescope. Then, the scientists managed to achieve success thanks to a fundamentally new method of analyzing archived images. The same method was used in a new study to study the composition of the atmosphere of Europa.
Difference between Europa and Ganymede
Experts explained that Europa reflects more sunlight than Ganymede, so it is much colder than its neighbor. The daily record recorded in Europa is minus 126 degrees Celsius. The average surface temperature of Ganymede is about 16 degrees Celsius higher than that of Europa.
Water ice on Europa
Despite extremely low temperatures, water ice on Europa, as shown by new observations, sublimates, that is, it passes from a solid state directly into vapor, bypassing the liquid phase. In this respect, both moons of Jupiter are similar to each other.
How did researchers make their discoveries?
We add that it was possible to discover the constant presence of vapor in Europa using the STIS spectrograph installed on the Hubble telescope. It allows observations in the ultraviolet spectrum. Thanks to this, astronomers first identified a fairly high content of oxygen – one of the components of water – in the atmosphere of Europa. And then, by varying the radiation at different wavelengths, they found evidence of the presence of water vapor.
Important facts about Europa
By the way, Europa has been intriguing scientists for many years. It is covered with ice all over its surface. Recent studies have shown that a huge ocean is hidden under the ice, which, in our opinion, is one of the prerequisites for the emergence and maintenance of life.
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• Dvorsky, G. (2021, October 15). Recurring water vapor potentially found on Europa-but just on one side. Gizmodo.
• Jenner, L. (2021, October 12). Hubble finds evidence of water vapor in one hemisphere of Europa. NASA.
• O’Neill, M. (2021, October 15). Hubble finds mysterious replenishment of water vapor on Jupiter’s moon europa. SciTechDaily.
• Phys.org. (2021, October 14). Hubble finds evidence of persistent water vapor in one hemisphere of Europa.
• Roth, L. (2021, October 14). A stable H2O atmosphere on Europa’s trailing hemisphere from HST Images. AGU Journals.