After last week NASA announced the discovery of molecular hydrogen in the subterranean ocean of Enceladus, a satellite of Saturn, the scientific community claims that extraterrestrial microbes or at least their tracks can be found on the icy moon. Despite the fact that the surface of Enceladus is covered with a thick layer of ice, astronomers believe that the ocean under the ice is incredibly warm – about 90oC.
In connection with this, debates on the topic of what the simplest xeno life could be like, flared up with renewed vigor. In 2015, the NASA Cassini spacecraft collected samples on Enceladus that contained fragments of organic compounds. The ice moon instantly turned from an ordinary satellite of Saturn (total of 62) into a real shrine of astrobiologists. The only question is, can there be a semblance of earthly organic life on a rocky area covered with ice crust?
At first glance, this is unlikely, since the surface of the moon reflects so much light that the temperature on its surface drops to -201 oC. This cold does not exclude the possibility of the appearance of life, but greatly complicates its functioning. According to Rocco Manicelli, an astrobiologist from NASA, the main question to be asked in this situation is “Where will life take the source of energy for self-reproduction and development?”
Because of the thick layer of ice, the energy that organisms could receive from sunlight is negligible. Life on Enceladus, if it is, will be concentrated around the hydrothermal vents that are key to maintaining marine ecosystems on Earth. The oldest fossil found today is a powerful argument in favor of the theory that life on our planet appeared exactly where water was heated and mineralized by hydrothermal wells. Next to them live even worms and some types of shrimp, despite the fact that this depth is almost not reach the sun’s rays. According to the Ocean Portal, these organisms survive by chemosynthesis, a process in which microorganisms at the very base of the food chain convert chemicals from hydrothermal wells into energy-efficient energy.
On Enceladus, there may not be all the conditions for the evolution of organisms into multicellular, complex forms, but the life of protozoa in a warm ocean is quite possible. How to know, maybe this kind of environment will turn evolution over another, yet unknown to us way? It is also possible that Enceladus microbes use bioluminescence for survival. In fact, it is simply the allocation of energy in the form of light radiation, which is characteristic of many deep-sea creatures of the Earth. Manichelli explains that for real bioluminescence a source of energy is also needed, and if there is one, scientists on Earth will be able to find it during a deeper study of the icy moon.
By the way, Enceladus Life Finder (ELF) is a special program that NASA is now developing specifically to search for traces of life on Enceladus. They will have to work hard, because the research apparatus will have to learn to detect not one, not two, but all possible traces of biological activity, considering also possible alternative ways of development of cosmic evolution.