When searching for alien life, it’s not unusual to use Earth as a test bed for theories and even practice runs. Perhaps one of the most tantalising places in the Solar System to look for life is Saturn’s moon Enceladus. It has a liquid water interior and it is here that life may just be possible. A team of researchers want to test techniques for searching for life on Enceledaus by exploring the oceans of Earth. They have collected water and ice samples and hope to find chemicals like methane and hydrogen.
The search for alien life is one of that has fascinated humanity for decades. Scientists explore this vast question through various avenues, including the study of exoplanets within the habitable zones of distant stars but there is still hope that maybe, just maybe we will find life elsewhere in our own Solar System. Some of the moon’s of the outer planets offer tantalising possibilities such as Enceladus, a moon of Saturn. It’s an icy moon where, beneath the icy crust, there is the possibility of the global ocean of liquid water teeming with life.
When the Cassini-Huygens probe visited Saturn in 2004 it sampled the cryogenic plumes that had been ejected over the southern pole, Using its Ion and Neutral Mass Spectrometer and Cosmic Dust Analyser, research teams identified the presence of water ice, methane and other carbon based molecules. Molecular hydrogen, molecular nitrogen and other elements all of which suggest the sub-surface ocean was a salty composition with the necessary elements for primative life. However to date, no evidence has been found.
It’s thought that the ice crust of Enceladus is anything form a few kilometres to up to 40 km thick. Beneath, and in the depths of the ocean are thought to be hydrothermal vents which, just like oceans on Earth, are a source of energy that could drive entire ecosystems. With all the ingredients for life, missions have been discussed to explore the astrobiological aspects of Enceladus. Mission with mass spectrometers have been proposed to identify biosignatures within the ocean.
In the paper published in Planetary and Space Science and written by a team led by F. French from the Università degli Studi di Bari in Italy, the team look at the technical possibility of detecting methane cycling on Enceladus. If it can be observed, then it would give a strong indication that the sub-surface ocean is currently, or has been habitable in the past. The conclusion can be quite reliably drawn since the methane cycle on Earth is often the result of biological and abiotic processes but is generally considered a byproduct of microbial activity.
NASA and ESA have been discussing possible missions to Enceladus but ahead of that, one way of practicing the ability to detect geochemical signatures of life is to see if it can be detected on Earth using the same technology. The Arctic Ocean is a great analogy to the conditions on Enceladus with vents on the sea floor in an ocean covered with ice for the majority of the year. The team conducted experiments to simulate the processes and techniques future missions are likely to employ on Enceladus and other outer moons.
The team found that they were able to detect and measure emitted concentrations of carbon dioxide, other carbon isotopies and other oxygen isotopes within the water. Their results suggest it will be possible to detect the necessary elements using a mass spectrometer at Enceladus. Further studies are appropriate to refine the processes ahead of a future mission.
Source : An Arctic Analogue for the Future Exploration of Possible Biosignatures on Enceladus