They find a fundamental element for life in the oceans of Enceladus

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The search for life beyond Earth has been strongly supported by dozens of observatories, telescopes and space probes. The last decades have given us a perspective on the signs or markers that can show if there is or was life. The so-called biomarkers are a series of compounds that can only exist in the presence of organisms, which in turn require the basic elements of organic chemistry, a clear example is phosphorus. Traces of it were found on Saturn's moon Enceladus by the Cassini probe.

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Mosaic of several high-quality images during a 2005 approach by the Cassini probe to the moon Enceladus. Credit: NASA/JPL/Space Science Institute

Enceladus: a frozen world

Water is a quite common element In the universe, although it is usually found in a solid state, there are processes that can thaw it. One of them is the case of the Earth, where the atmosphere allows a stable ideal temperature. However, this is the exception to the rule. Another possibility is the incredible tidal forces of gas giants that can induce heat in the interior of some moons.

Enceladus is the brightest body in the solar system, this when we consider its extensive, smooth and clean ice surface capable of reflecting more than 90 % of the light it receives. Beneath a thick shell hides a deep ocean of liquid water. This is known thanks to the ejections of water through geysers and cracks at the south pole. This emission of material is also responsible for feeding Saturn's E ring.

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During a flyby, the Cassini probe captured an ice ejecta from the moon Enceladus toward the E ring. Credits: NASA/JPL/Space Science Institute

Phosphorus: a pillar for life

Despite its relative low abundance, phosphorus is key to a large number of biological processes. It serves as material to make DNA, chromosomes and, in general, store genetic information.. Previous studies had found a variety of organic compounds in Enceladus's oceans, but never a definitive signature of phosphorus.

Using data from the Cassini probe, which explored the Saturn system between 2004 and 2017, astronomers found not only a clear trace of phosphorus, but a great abundance of it. Marking the first time it has been found in an ocean outside of Earth.           

This was possible thanks to the cosmic dust analyzer instrument, which managed to study small samples of ice in Saturn's E ring. Supplemented with small particles during a flyby. This resulted in the discovery of high concentrations of sodium phosphates, compounds of oxygen, sodium, hydrogen and phosphorus.

In search of extraterrestrial life

The processes that could produce such an amount of phosphorus on Enceladus can occur on many other similar icy worlds. Although all the basic elements for life have been found outside Earth, So far there is no other place inhabited by organisms. The search continues, motivated by the desire to determine if we are alone in the universe.

Francisco Andrés Forero Daza