Webb telescope's study suggests life on exoplanet remains unconfirmed

Webb telescope's study suggests life on exoplanet remains unconfirmed
by Clarence Oxford
Los Angeles CA (SPX) May 03, 2024

Excitement was high when NASA's James Webb Space Telescope reported potential signs of life on a distant exoplanet. However, a new study by UC Riverside researchers published in the Astrophysical Journal Letters tempers these claims, discussing both the limitations and future possibilities of confirming life on such planets.

The research focuses on the exoplanet K2-18b, which in 2023 appeared to host biosignature gases in its atmosphere. Unlike most exoplanets, K2-18b receives a similar amount of solar radiation as Earth and has a comparable temperature, making it a prime candidate for supporting life.

"The DMS signal from the Webb telescope was not very strong and only showed up in certain ways when analyzing the data," said UCR project scientist Shang-Min Tsai, discussing the challenges of detecting dimethyl sulfide (DMS) on K2-18b. DMS is a compound produced by ocean phytoplankton on Earth and is key to cloud formation.

Despite the optimistic reports, the atmosphere of K2-18b, rich in hydrogen and speculated to house water oceans, does not mirror Earth's nitrogen-based air. Last year, findings suggested the presence of methane and carbon dioxide, along with a possible detection of DMS on K2-18b.

"We wanted to know if we could be sure of what seemed like a hint about DMS," Tsai said. Tsai noted, "The signal strongly overlaps with methane, and we think that picking out DMS from methane is beyond this instrument's capability." According to their models, DMS could be a significant biosignature on planets with hydrogen-rich atmospheres like K2-18b.

The study emphasizes that detecting life on remote exoplanets is a formidable challenge due to their vast distances. Advanced instruments capable of analyzing infrared wavelengths more effectively are necessary for a definitive detection, which the Webb telescope is slated to use later this year.

Senior author Eddie Schwieterman, a UCR astrobiologist, explained, "The best biosignatures on an exoplanet may differ significantly from those we find most abundant on Earth today. On a planet with a hydrogen-rich atmosphere, we may be more likely to find DMS made by life instead of oxygen made by plants and bacteria as on Earth."

The team remains driven by the fundamental curiosity about what lies beyond our planet. "Why do we keep exploring the cosmos for signs of life? Imagine you're camping in Joshua Tree at night, and you hear something. Your instinct is to shine a light to see what's out there. That's what we're doing too, in a way," Tsai shared.

Research Report:Biogenic sulfur gases as biosignatures on temperate sub-Neptune waterworlds