Europa is slightly smaller than Earth’s moon and orbits Jupiter every 3.5 days. It is believed to have an iron core, a rocky mantle, and an ocean of salt water, just like Earth. It is quite light in color due to the abundance of ice on its surface. In Europe, days can reach high temperatures that are excessively low, -163 ºC at the equator and -223 ºC at the poles. But even at such stunning temperatures, recent observations show that water sublimates or undergoes a phase change directly from solid to vapor, bypassing the liquid state. And it is something that is happening directly from the surface of Europa, just like Ganymede.
Although the presence of water vapor on Jupiter’s moon Europa was identified in 2013, these Hubble observations confirm that water vapor is persistent in one of the satellite’s hemispheres; in the final hemisphere, that is, the part that is always opposite to its direction of motion in the orbit.
Only in one of its hemispheres
Half of Europe is under a thin veil of water vapor. And data from NASA’s Hubble Space Telescope suggest that the moon has water vapor on its surface in a stable manner, according to a recent study published in the journal Geophysical Research Letters .
Interestingly, it’s only present in one hemisphere, something researchers don’t yet understand. Why is water vapor only in the final hemisphere and not in the main hemisphere? They do not know it. This information could have a significant influence on NASA’s upcoming missions to Europa and the search for life on alien worlds.
The study used archival images and spectra from Hubble, courtesy of a novel technique that also recently detected water vapor in the atmosphere of Jupiter’s other moon, Ganymede. The presence of water vapor in Europa, Jupiter’s fourth largest moon, was established as early as 2013. However, this new finding indicates that there is water vapor in a significantly larger portion of the moon than previously thought , with data spanning between 1999 and 2015. This means that the Jovian moon supports a long-term atmosphere of water vapor , on the opposite side of the direction of the orbit of the host planet’s icy body, Jupiter.
“Observing water vapor on Ganymede, and on the back side of Europa, advances our understanding of the atmospheres of icy moons. However, detecting a stable water abundance in Europa is a bit more surprising than in Ganymede because Europa’s surface temperatures are lower than Ganymede’s, ”explains Lorenz Roth of the Royal Institute of Technology, Space Physics. and KTH Plasma and study author.
With missions to Europa like NASA’s Clipper, European Space Agency (ESA) Jupiter Icy Moons Explorer (JUICE) and a few more underway, whether or not they find signs of life on Jupiter’s moons, we will certainly learn more about evolution. of the Jovian system.
Clipper will reach the Jovian moon in 2030 , so we may not have to wait too long to find out if this icy body is habitable for humans and capable of supporting life.
Referencia: Lorenz Roth, A stable H 2 O atmosphere on Europa’s trailing hemisphere from HST images, Geophysical Research Letters (2021). DOI: 10.1029/2021GL094289
