Will scientists searching for signs of life elsewhere in the solar system live to regret their recent decision to send NASA to Saturn’s moon Enceladus instead of Jupiter’s moon Europa?
Both moons are known to have oceans of salty water beneath their thick icy surfaces, and both appear to have geysers that send some of that water, as steam, into space. The recent Decadal Survey for Planetary Science and Astrobiology decided that Enceladus’ plumes were more reliable and easier to sample than Europa’s, thus bypassing the $5.8 billion Europa Lander mission in favor of Enceladus Orbilander. of 4.9 billion dollars.
It now appears that Europa may have a large number of “pockets of water” just below its ice cap, and possibly oxygen in its ocean.
Published in nature communications, a new study used ice-penetrating radar in Greenland. They did so because they noticed that the ridges on the icy moon closely resembled a minor feature on the surface of the Greenland ice sheet, which they had already studied in detail.
It suggests that Europa’s ice sheet may not be a barrier to exploration, but a more dynamic place that could be habitable.
“Because it’s closer to the surface, where you get interesting chemicals from space, from other moons, and from volcanoes on another moon of Jupiter called Io, there’s a chance that life has a chance if there are pockets of water on Earth. shell”. said Dustin Schroeder, lead author of the study and an associate professor of geophysics in the Stanford University School of Earth, Energy and Environmental Sciences. “If the mechanism we see in Greenland is how these things happen in Europe, it suggests that water is everywhere.”
The researchers were working on the science of climate change when they noticed that an M-shaped ridge in Greenland could be a miniature version of an obvious feature in Europe.
You can see them in any image of Europa, like this one below, as dramatic cuts in the icy surface. They reach nearly 1,000 feet and are separated by valleys about a half-mile wide.
Shallow pockets of water in Europe
The image above is actually from NASA’s Galileo orbiter, which was the first spacecraft to detect the features on Europa in the 1990s.
The next big close-up that scientists will get of Europa will be of Juno. By the end of September 2022, it will reach just 355 kilometers (221 miles) above the surface of Europa.
“In Greenland, this double ridge formed in a place where water from surface lakes and streams frequently drains near the surface and refreezes,” said Riley Culberg, the study’s lead author and a doctoral student in electrical engineering. at Stanford. “One way that similar shallow pockets of water could form on Europa could be through subterranean ocean water being forced up into the ice sheet through fractures, and that would suggest there could be a reasonable amount exchange within the ice sheet.
For a long time, Europe was thought to be a geologically active and dynamic place. “We are taking a much bigger step in the direction of understanding what processes actually dominate the physics and dynamics of the Europa ice sheet,” said study co-author Gregor Steinbrügge, a planetary scientist at the Jet Propulsion Laboratory (JPL). of NASA, who began working on the project as a postdoctoral researcher at Stanford.
But could there be something living in the underground ocean?
Europa’s ocean life?
Another recent study of Europa, this time using computer simulations of its “chaotic terrain” surface, was published in Geophysical Investigation Letters during March 2022. It suggests that oxygen could be traveling in salt water to its subterranean ocean.
In fact, their results show that the amount of oxygen reaching Europa’s ocean could be similar to that in Earth’s oceans. Cue the possibility of aquatic aerobic organisms.
“Our research puts this process in the realm of possibility,” said lead researcher Marc Hesse, a professor in the Department of Geological Sciences at the UT Jackson School of Geosciences. “It provides a solution to what is considered one of the outstanding problems of habitability of the subterranean ocean of Europe.”
Two missions to Europe
Although the Europa Lander concept is dead for now, Europa is not being totally ignored. NASA’s Europa Clipper mission will launch in October 2024 and arrive in late 2027 to make some 45 flybys, each time photographing the icy surface of the moon in high resolution.
It may help improve estimates of oxygen and other ingredients for life on the icy moon.
Meanwhile, the European Space Agency’s JUpiter ICy moons Explorer (JUICE) will launch in May 2022, arrive in 2029 and take three and a half years to survey Europa, as well as two of Jupiter’s other Galilean moons, Ganymede and Callisto. .
I wish you clear skies and wide eyes.