A recent study led by astrobiologist Catherine Neish from the Western Institute for Earth and Space Exploration has dealt a blow to hopes of finding life in the outer solar system, particularly on Titan, Saturn’s largest moon. Neish’s team found that the subsurface ocean on Titan, though vast, is likely a non-habitable environment, dashing the optimism of many in the scientific community.
This discovery has significant implications for space scientists and astronauts, as it reduces the likelihood of finding life in the outer solar system, home to the gas giants Jupiter, Saturn, Uranus, and Neptune. “Unfortunately, we will now need to temper our optimism when searching for extraterrestrial life within our own solar system,” remarked Neish, an Earth sciences professor leading the study.
The outer solar system has long been of interest to planetary scientists, astronomers, and space agencies like NASA due to the presence of icy moons with subsurface oceans. Titan, in particular, is thought to harbor a vast ocean beneath its icy surface, over 12 times the volume of Earth’s oceans.
The study, published in Astrobiology, focused on quantifying the transfer of organic molecules from Titan’s surface to its subsurface ocean, using data from impact cratering. Comets striking Titan’s surface throughout its history have melted the ice, creating pools of liquid water that may have mixed with surface organics and percolated down to the subsurface ocean.
By estimating the rates of impacts on Titan’s surface, Neish and her team calculated the flow rate of water carrying organics from the surface to the interior. The results were sobering—only a small amount of organics, including the simplest amino acid glycine, are transferred to the subsurface ocean each year, equivalent to the mass of a male African elephant.
“This minimal transfer of organics is insufficient to sustain life in Titan’s subsurface ocean,” explained Neish. “While water is crucial for life as we know it, the presence of other elements, particularly carbon, is equally important.” This finding underscores the complexity of the search for extraterrestrial life and highlights the need to consider a broader range of factors beyond just the presence of water.