One of the main purposes of exploring the Universe is to find life outside our planet. An important step in this search was revealed yesterday when a team of scientists revealed that they had found evidence of the presence of phosphorus on Enceladus, one of Saturn’s 82 moons. “This is a surprising result for astrobiology and a great step forward in the search for life beyond Earth,” says American geochemist Christopher Glein, who has published the results together with other specialists in the journal ‘Nature’.
Phosphorus in the form of phosphates is an essential element for life as we know it. It is present in both DNA and RNA, it is essential in the formation of bones and teeth and is essential for the body to generate energy. Scientists have detected their presence “in concentrations at least a hundred times higher than in Earth’s oceans” in a type of enormous geysers of ice particles that emerge towards the surface of Enceladus from an underground ocean and form one of the known rings of Saturn – the E ring, specifically. This is the first time it has been found in an ocean outside our planet. “By determining such high concentrations of phosphate in the Encédalus ocean, one of the requirements established to establish whether a celestial body is habitable is met,” adds Fabian Klenner, another of the authors of the study.
Experts consider the discovery of oceans beneath a surface layer of ice on other planets and satellites to be one of the most important milestones of the last 25 years. In addition to Enceladus, it is known to be present on two other icy moons of Saturn on Titan, a satellite of Jupiter, and on Pluto.
The key role of the Cassini probe
The discovery of the phosphorus was possible thanks to the Cassisi mission, sponsored by NASA in collaboration with the European Space Agency (ESA) and the Italian Space Agency (ASI). Launched in 1997, this probe explored Saturn and its surroundings for more than 13 years, between 2004 and 2017. After discovering the aforementioned geysers a year after its arrival, thanks to its observations they also determined that the underground ocean is unique and extends all of Enceladus. Already in 2015, engineers decided to let it pass through one of those jets that sprout from the satellite to collect samples. It was only 49 kilometers from the surface. The result is what has now been known, the abundant presence of a fundamental element for life.
Cassini also made it possible to adjust the age of Saturn’s seven rings. If it was previously thought that they emerged more or less at the same time as the gas giant 4.5 billion years ago, it is now known that they are much ‘younger’, between 100 and 400 million. They are fundamentally formed by small fragments of ice and rock, they have a thickness of half a kilometer – in some points it is only ten meters – and a diameter of 270,000 kilometers, more than half the distance that separates our planet from the Moon. The other gas giants in the Solar System – Jupiter, Uranus and Neptune also have them – but Saturn’s are the only ones visible from Earth.
Last March, another element essential for life was discovered on the Ruyugu asteroid. Uracil, one of the components necessary to form RNA, was found. This finding suggests that nucleotides – the components that make up both DNA and RNA. Both have three of them in common, adenine (A), cytosine (C) and guanine (G). It is the fourth that differentiates them. DNA contains thymine (T), while RNA, the aforementioned uracil (U) – have an extraterrestrial origin and arrived on our planet from the impact of carbon-rich meteorites such as Ruyugu between 4,100 and 3,800 million years ago.