Titan in ultraviolet and infrared wavelengths, as captured by the Cassini probe in 2004
NASA/JPL/Space Science Institute
Researchers have discovered an enigmatic substance on the surfaces of Pluto and Saturn’s moon Titan, yet its identity remains unknown.
Due to Titan’s dense atmosphere, examining its surface is challenging. Identifying this unknown compound could shed light on the intricate chemistry occurring there. Titan is a compelling target in the search for extraterrestrial life, and understanding its chemical makeup is crucial.
Astronomers use spectroscopy to determine the composition of distant celestial bodies. This technique involves analyzing the wavelengths of light absorbed, reflected, or emitted by various substances.
Bruno Bézard from the Paris Observatory and his team identified this compound using data from the James Webb Space Telescope (JWST). They observed a specific narrow-wavelength band of light being absorbed on Titan’s surface and noticed a similar absorption, albeit with a wider spread, on Pluto.
While Pluto and Titan appear different—Pluto is colder, lacks surface liquid oceans, and has an atmosphere 15,000 times less dense—their atmospheric chemistry is surprisingly similar. “Both atmospheres are predominantly nitrogen and methane, which leads to the production of haze particles that can settle on the surface,” explained Bézard. This process likely contributes to the formation of the mysterious compound.
The researchers compared the spectral signature found on both celestial bodies with numerous spectra from astronomical observations and laboratory experiments. These represented known compounds in Titan’s atmosphere and potential ice forms on both surfaces. However, none provided a perfect match.
Some spectra were nearly matches, suggesting the mystery compound might be a slightly altered version or mixed with other molecules. Additionally, differences in the substance’s form on Pluto and Titan, such as grain size variations, might exist. “We have a few candidates, but it will not be a simple compound,” Bézard stated, adding, “Whatever it is, it will be a surprise.”
To further investigate, the researchers are pursuing a three-pronged strategy. They have acquired additional data from JWST, which might help determine the location of the substance on Titan’s surface. Geological features there may offer insights. Concurrently, laboratory experiments are being conducted to see if the near-matches can align with the mystery spectral feature. Lastly, NASA’s Dragonfly spacecraft, set to launch in 2028 and land on Titan in 2034, could provide definitive answers.
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