Why it matters: Carbon is one of the primary building blocks of life as we know it. Therefore, the detection of carbon signs on celestial bodies other than Earth is always a significant discovery. Thanks to JWST's powerful instruments, scientists now have evidence that carbon should be abundant on one of the most promising targets for extraterrestrial life research.
Two new studies suggest that the Jovian moon Europa hosts one of the essential elements needed for life. Based on observations and data collected by the James Webb Space Telescope, the authors of these papers explain that they have detected a newly identified source of subsurface carbon in a specific region of Europa's icy surface.
Europa is the smallest of the four Galilean moons orbiting Jupiter and the sixth-largest moon in the entire solar system. It is one of the few celestial bodies in our solar system that could potentially harbor life, as it possesses a subsurface, salty ocean of liquid water beneath its icy crust. Prior to Webb, there were no direct confirmations that Europa's ocean contained the elements necessary for life.
Astronomers have made a historic confirmation that Europa indeed possesses carbon sources, most likely originating from the moon's subterranean ocean. Webb successfully detected significant traces of carbon dioxide in a region known as Tara Regio, characterized by its geologically young, resurfaced terrain, often referred to as "chaos terrain."
Surface ice in Tara Regio has been disrupted, as explained by scientists, possibly indicating an exchange of materials between the subsurface ocean and the surface. Previous observations from the Hubble Space Telescope supported the presence of ocean-derived salt in Tara Regio. Now, we have definitive evidence that the region also hosts "heavy" sources of carbon dioxide.
Both studies identified carbon dioxide using the integral field unit of Webb's Near-Infrared Spectrograph (NIRSpec) instrument. This tool provides spectral data with a resolution of 320 x 320 kilometers, while Europa has a diameter of 3,128 kilometers. Since carbon dioxide cannot maintain a stable state on Europa's surface, scientists conclude that this recently discovered concentration is relatively "young" on a geological timescale.
The researchers also attempted to find evidence of water vapor plumes emanating from Europa's surface, similar to what JWST has already detected on Saturn's moon Enceladus. Up to this point, no "definitive" proof of water plumes has been uncovered on Europa.
These new findings will assist scientists in designing and planning their upcoming space missions aimed at studying the Jovian moon. ESA's Juice spacecraft was launched on April 14, 2023, and NASA's Europa Clipper is scheduled for launch in October 2024.