Recent NASA studies have revealed that there are oceans beneath the ice crust on the satellites of Jupiter, Europe, and Saturn, Enceladus. These oceans may support life and can preserve organic molecules, such as amino acids, under the surface ice despite the harsh radiation environment. This discovery indicates that future robotic probes will not need to drill deeply to search for signs of life on these moons.
The experiments conducted by NASA have shown that in Europe, a safe depth for collecting amino acid samples is around 20 centimeters in the high latitude region of the rear hemisphere, where the surface is less disturbed by meteorites. On Enceladus, amino acids can survive at a depth of less than a millimeter from the surface.
Although the surfaces of these moons are not conducive to life due to intense radiation, the subsurface oceans beneath the ice crust could potentially support life. The heat generated by tidal forces from the gravity of the planets and neighboring moons can create conditions suitable for life in these hidden oceans, which may contain essential elements and compounds.
Amino acids are crucial building blocks for proteins, which are essential for life. The experiments conducted by NASA showed that amino acids can reach the surface through geyser activity or slow mixing of the ice crust. To assess the survival of amino acids, researchers exposed them to gamma rays under low temperatures, simulating the conditions on Europe and Enceladus. They also tested amino acid samples mixed with dead bacteria and ice with silicate dust to account for potential meteorite or internal material mixing with the surface ice.
Results indicated that amino acids degrade faster in mixtures with dust, but more slowly in the presence of bacteria. This emphasizes the importance of selecting sampling sites carefully for future missions to these moons to maximize the chances of detecting preserved organic molecules.
The findings of the research, published in the journal Astrobiology, provide new hope for the potential discovery of signs of life beyond Earth. Future missions to Europe and Enceladus should consider the radiation conditions and strategically choose sampling sites to enhance the possibility of finding preserved organic molecules.