Jupiter’s icy moon, Europa, may contain carbon, a key ingredient for life, data collected by NASA’s James Webb Space Telescope (JWST) has revealed.
Europa, the sixth-largest moon in the solar system, is one of the most-promising worlds in the search for life outside our planet. The evidence uncovered to date suggests that a salty ocean of liquid water with a rocky seafloor lies hidden below the moon’s thin water-ice crust.
Scientists think this subsurface ocean could potentially harbor conditions that are suitable for extraterrestrial life. However, the chemical composition of this ocean and whether it contained the ingredients needed for life, particularly carbon, have remained poorly known.
SETI Institute / JPL-Caltech / NASA /
Now, a pair of independent studies published in the journal Science, based on observations made by JWST, have uncovered evidence that the subsurface ocean may contain carbon.
Scientists determined that carbon dioxide (CO2) found in a specific region on the icy surface of Europa likely originated in the subsurface ocean. It was not delivered by meteorites or other mechanisms. The results have important implications for the potential habitability of the moon’s ocean.
“I think these results are a step in the right direction,” Samantha Trumbo, an author of one of the studies with the Department of Astronomy at Cornell University in Ithaca, New York, told Newsweek.
“They provide further evidence that material sourced from the ocean has made it to the surface, where we can study its composition and thereby gain insight on the chemistry of that internal ocean. Building up a more-complete picture of what that chemistry is like will be important for eventually understanding the potential ocean habitability,” Trumbo said.
Scientists have known that there is carbon dioxide on the surface of Europa since the discoveries of NASA’s Galileo mission, which arrived at Jupiter in 1995. The probe studied the planet and its numerous moons for several years before its mission came to an end in 2003.
Despite the data collected by the Galileo probe, researchers were still not sure whether the CO2 on Europa’s surface came from the interior of the moon—and was therefore related to the subsurface ocean chemistry—or if it instead originated from an external source.
“We were really interested in answering this question by looking at the distribution of CO2 across the surface with the JWST data. We wanted to understand if the CO2—the only carbon-bearing species so far detected on Europa’s surface—was related to the ocean composition,” Trumbo said.
In their study, she and her colleagues analyzed near-infrared data collected by JWST to map the distribution of CO2 on Europa’s surface, finding the highest abundance in a region known as Tara Regio. This covers an area of roughly 700 square miles, characterized by what planetary scientists call “chaos terrain”—meaning that it is geologically young and features resurfaced materials.
The amount of CO2 found in this region—which represents some of the youngest terrain on Europa’s surface—indicates that it came from an internal source of carbon. The implication of the findings is that the carbon dioxide formed within Europa’s subterranean ocean and was brought to the surface relatively recently, geologically speaking.
“Europa’s CO2 appears to lie preferentially within large-scale disrupted ‘chaos’ terrains on the surface, particularly the region known as Tara Regio, which we previously showed to also contain ocean-derived table salt using data from the Hubble Space Telescope,” Trumbo said. “This really suggests to us that the CO2 is sourced from the interior.
“Our findings suggest that carbon, likely in the form of CO2, is present in Europa’s internal ocean and has reached the surface on a geologically recent timescale,” Trumbo added. “Indeed, the average surface age of Europa is estimated to be less than 90 million years old—very young compared to the 4.5-billion-year history of the solar system—and chaos terrains like Tara Regio represent some of the youngest regions.”
In another study based on the same JWST data, Geronimo Villanueva—with the NASA-Goddard Space Flight Center—and colleagues found that the CO2 on Europa’s surface is mixed with other compounds.
This team also discovered that this CO2 is concentrated in Tara Regio and came to the conclusion that this provides evidence for the carbon being sourced from within.
The results of both studies support the conclusion that Europa’s subsurface ocean contains abundant carbon.
In October 2024, NASA plans to launch its Europa Clipper spacecraft, which will conduct several flybys of the moon. The aim is to shed more light on the potential habitability of the icy world.