James-Webb searches for life in the giant water plume of Saturn’s moon Enceladus

We remember the spectacular announcement in December 2013 of the observation by the telescopetelescope Hubble of two 200 kilometer high water vapor plumes rising from thesouthern hemispheresouthern hemisphere of Europe, the moonmoon ice of Jupiter possessing a global ocean covered with a pack icepack ice. As Futura explained in the previous article below, the James Webb Space TelescopeJames Webb Space Telescope follows in the footsteps of HubbleHubble regarding the exploration of Solar systemSolar system and it allowed planetologists to discover and determine the extent of a plume of water vapor rising this time from Enceladus, another icy moon similar to Europa but in orbitorbit around SaturnSaturn.

A publication was expected and we now know that it is in the form of an article by Nature Astronomy. As a NASA press release explains, Enceladus and its geysersgeysers therefore generate a plume whose size is more than 9,600 kilometers above this moon whose diameter is about 500 kilometers. The geysers behind this plume have already been detected for several years by the defunct Cassini probe and it is estimated today that they inject into space, in the form of steam and ice, around 300 liters of water per second.

A video about the discovery of hydrothermal vents on Enceladus. To obtain a fairly accurate French translation, click on the rectangle with two horizontal bars at the bottom right. The English subtitles should then appear, if they haven’t already. By then clicking on the nut to the right of the rectangle, you should see the expression “Translate subtitles”. Click to bring up the menu for choosing the language, choose “French”, then click on “OK”. © NASA, JPL-Caltech

Hydrothermal springs that harbor life elsewhere than on Earth?

As we had explained in a previous article the astrochemist, exobiologist and planetologist OlivierOlivier Poch, the analysis of water plumes from the interior of Europe and Enceladus could give us in the near future valuable information to support the hypothesis that there are life forms around hydrothermal vents. in the oceans of these two moons.

The James-Webb instruments being more sensitive than those of Hubble, they already make it possible to obtain some constraints from the ground on the composition, size and dynamics of the giant plume produced by Enceladus, a plume which not only feeds a torus of steam of water around Saturn but also the rest of the Saturnian system, that is to say its multiple rings and other small moons. Observations and measurements of the James-Webb make it possible to estimate that approximately 30% of the water remains in this torus.

We are only at the beginning of the Enceladus observation program with the James-Webb and it will certainly help us to learn more about this moon while waiting for the return of a space mission of the scale of Cassini. . In the meantime, the biggest surprises for theexobiologyexobiology may come from Europe with NASA’s Europe-Clipper probe.

An animation showing the moons of Saturn with the plume of Enceladus. © NASA, ESA, CSA, G. Villanueva (NASA’s Goddard Space Flight Center), A. Pagan (STScI), L. Hustak (STScI)

Identified by the Cassini probe in 2005, the plumes of water ice ejected by Enceladus could turn out to be much more powerful than previously thought. Saturn’s small moon would thus spit out a quantity of water and moleculesmolecules organisms far away in space. A phenomenon once again testifying to potentially favorable conditions of habitability under the frozen surface of this moon.

Article of Morgane GillardMorgane Gillardpublished on May 23, 2023

Orbiting Saturn, Enceladus fascinates with its amazing features and the mystery that lies beneath its thick crustcrust of ice. Because it has been assumed for a long time now that this small satellite of only 500 kilometers in diameter could well shelter a vast ocean of salty liquid water, with, why not, extraterrestrial life. Because all the conditions seem met: water, presence of organic molecules and heat.

All the ingredients necessary for life gathered under the frozen surface

In 2005, the Cassini probe made an astonishing discovery during its overviewoverview of Saturn’s satellite. The immense cracks traversing the frozen surface of the small moon indeed eject particles of water ice, producing a snow coming to be deposited continuously on the frozen crust of a hundred meters in thickness. In addition to providing proof that Enceladus is in some way an “ocean world”, this observation shows that the bowels of the moon are subject to intense geothermal activity, a source of heat. Add to that the presence of organic molecules (methane, carbon dioxidecarbon dioxide and ammonia) in the ejected plumes of water and you have all the ingredients necessary for the development of life.

Huge geysers that expel water and organic molecules into space

New JWST observations (James Webb Space Telescope) now support this hypothesis. They also show that the plumes could be much more powerful than previously thought, spewing huge amounts of water and organic molecules far into space. If the dimensions of these plumes were not revealed during the press conference given on May 17, they should soon appear in a scientific article. This should also review the chemical compounds identified in these cloudsclouds of water ice. Results that promise to be interesting!

In the meantime, scientists are scheduling new observation sessions using the JWST. The objective is now to detect chemical compounds associated with biological activity or indicative of favorable conditions of habitability under the protective layer of ice.