James Webb spots carbon on Europa, boosting case for life
The best places in our solar system to search for life beyond Earth aren’t planets like Mars – they’re icy moons like Europa. The case for life on this watery world just got stronger, as the James Webb Space Telescope has detected a fresh carbon source there.
It might not look very hospitable, but Jupiter’s moon Europa is high on the list of promising places to find extraterrestrial life. Astronomers believe that beneath its icy shell lies a global ocean that’s surprisingly similar to those here on Earth. And where there are Earth-like conditions, there could be Earth-like lifeforms.
Now, the James Webb telescope has discovered new evidence of carbon, an element that’s essential for life as we know it, on Europa. And most importantly, it appears to have come from the ocean below, rather than meteorites or other sources from above.
“We now think that we have observational evidence that the carbon we see on Europa’s surface came from the ocean," said Samantha Trumbo, lead author of a study analyzing the data. "That's not a trivial thing. Carbon is a biologically essential element."
The discovery was made using the spacecraft’s Near-Infrared Spectrograph (NIRSpec) instrument, which took infrared measurements of the moon’s surface. Scientists can then analyze the specific patterns of how the light reflects back to determine which specific chemicals are present and where they are.
In doing so, the team found large deposits of crystallized carbon dioxide and complex, amorphous carbon dioxide in several regions of Europa’s surface. The CO2 is most abundant in an area called Tara Regio, which is marked with “chaos terrain” where the surface ice is disrupted and interacts with the subsurface ocean below. Bolstering the ocean origin hypothesis is the fact that CO2 isn’t stable on the surface, indicating it was deposited there relatively recently.
“Previous observations from the Hubble Space Telescope show evidence for ocean-derived salt in Tara Regio,” said Trumbo. “Now we’re seeing that carbon dioxide is heavily concentrated there as well. We think this implies that the carbon probably has its ultimate origin in the internal ocean.”
Previous studies have detected what could be plumes of water shooting out through the ice from the ocean below, which could be one mechanism for how the carbon dioxide ends up on the ice. These observations didn’t catch any plumes in the act though, but that doesn’t mean there aren’t any – just that they could be intermittent.
More evidence for the presence of life on this intriguing icy moon could be discovered sooner rather than later, as NASA plans to launch the Europa Clipper mission in October 2024.