Saturn’s moon could harbour ALIEN life: Scientists discover organic molecules in Enceladus’ plume that suggest it could be habitable

• Saturn has over 100 moons but Enceladus is the one with a liquid water ocean
• Experts already know there’s phosphates, methane, hydrogen and CO2 there

It’s one of the most beautiful objects in our solar system, a shimmering sphere of pure white ice, hiding a liquid ocean within. 

But despite looking nothing like our planet, Enceladus, Saturn’s sixth-largest moon, may have something in common with Earth – the presence of life. 

Scientists have discovered organic molecules in the moon’s plumes that could be supporting ‘communities’ of tiny microbes. 

Researchers think these compounds could support their metabolisms or the formation of amino acids. 

Experts already know that there are phosphates, methane, hydrogen and carbon dioxide on Enceladus – all potential signs of life as well.  

Enceladus – Saturn’s sixth-largest moon – is a frozen sphere just 313 miles in diameter (about one-seventh the diameter of Earth’s moon). It is pictured in this image captured by NASA’s Cassini spacecraft

Plumes emanating from Saturn’s moon Enceladus contain compounds including hydrogen cyanide (HCN), acetylene (C2H2), propylene (C3H6) and ethane 

Molecules in Enceladus’ plumes 

Previously known

– Water 

– Carbon dioxide 

– Methane 

– Ammonia 

– Molecular hydrogen 

– Phosphates 

Newly discovered

– Hydrogen cyanide

– Acetylene 

– Propylene 

– Ethane 

– Traces of an alcohol (methanol) 

– Traces of molecular oxygen

The findings were detailed in a new study led by Jonah Peter, a PhD candidate in biophysics at Harvard University in Boston.

‘Here we present the detection of several additional compounds of strong importance to the habitability of Enceladus,’ the authors say. 

‘Our results indicate the presence of a rich, chemically diverse environment that could support complex organic synthesis and possibly even the origin of life.’ 

Enceladus has an outer layer of ice at least 12 miles thick that covers a liquid ocean of water within. 

Long, snake-like fractures on its icy surface eject huge plumes made up of ice grains and water vapour out into space. 

At least some of these plumes are believed to be frozen droplets from the mysterious liquid ocean – possibly a pristine underwater abyss teeming with lifeforms. 

Before it ended its mission in 2017, NASA’s Cassini spacecraft not only imaged Enceladus’ plumes but flew directly through them. 

Along with colleagues, Mr Peter studied data from Cassini’s Ion and Neutral Mass Spectrometer (INMS) collected during flybys in 2011 and 2012.

The team used a statistical analysis technique that analysed billions of potential compositions of the plume material. 

Enceladus, Saturn ‘s sixth-largest moon, has an outer layer of ice that covers a liquid ocean of water. Researchers have detected phosphates in ice ejected in ‘plumes’. These plumes are made up of water vapour and ice grains that are thought to have come from the ocean

This image imagines a cross-section of Enceladus. Note the long fractures on the icy surface ejecting plumes. These plumes are made up of ice grains and water vapour 

READ MORE Scientists discover phosphates on Enceladus 

The moon’s water contains phosphates – a key element for the existence of life 

From this, they identified that the most likely composition of the plumes is the five already identified molecules – water, carbon dioxide, methane, ammonia and molecular hydrogen. 

The fact the moon spews out methane gas is exciting because this is an organic molecule typically produced or used by microbial life.

The presence of methane in these plumes has led scientists to hypothesise that microbes may be living, or have lived, underneath Enceladus’ shell.

But the authors found there’s also newly identified molecules of hydrogen cyanide (HCN), acetylene (C2H2), propylene (C3H6), and ethane (C2H6), as well as traces of an alcohol (methanol) and molecular oxygen. 

‘Such compounds could serve as direct substrates for biological growth, or be intermediaries of other metabolic reactions involving additional organics and oxidants,’ the team say. 

The ability of these compounds to support life on Enceladus depends largely on how diluted they may be in the moon’s subsurface ocean, the authors note. 

Cassini is depicted here in a NASA illustration. Cassini launched from Cape Canaveral, Florida in October 1997

But the team are hopeful there’s a complex and diverse ‘hydrothermal environment’ beneath the moon’s icy outer shell, likely at the bottom of the ocean floor.

The presence of acetylene and ethane in the plume further implies ‘ongoing catalytic reactions’ that are being driven by metal-bearing minerals within the ocean. 

One day, experts will have made all the assumptions they can make about Enceladus from the Cassini data – and at this point further missions will be required.

Determining for sure whether life exists, or has existed on Enceladus, could very likely be the job of another spacecraft.

Until then, science-fiction authors will surely be inspired by the unique geological formation of this ice world, 313 miles away from humankind. 

‘More detailed examination of Enceladus’s oceanic material will require future robotic missions,’ the study authors conclude. 

The full findings have been published in Nature Astronomy. 

Once considered a frigid and inactive world, Enceladus is now a key focus for scientists in the hunt for alien life 

Enceladus is one of few locations in our solar system with liquid water, along with Earth and Jupiter’s moon Europa, making it a target of interest for astrobiologists. 

Enceladus was discovered by German-born astronomer William Herschel in 1789, using his 40-foot telescope in Slough, built only thanks to a £4,000 grant from King George III. 

However, it wasn’t until NASA’s Cassini probe reached Enceladus in 2005 that it was considered anything other than a frigid and inactive world. 

The spacecraft discovered evidence of the moon’s large subsurface ocean and sampled water from geyser-like eruptions that occur through fissures in the ice at its south pole, known as ‘tiger stripes’. 

Due to the presence of water, Cassini’s status was elevated as one of the prime targets to search for conditions suitable for past or present life.

Near Enceladus’ south pole, the ocean underneath the icy shell spews methane gas – an organic molecule typically produced or used by microbial life (artist’s impression)

Previous research has shown that Enceladus hides a ‘soda ocean’ (rich in dissolved carbonates) and contains a vast variety of reactive and sometimes complex organic compounds. 

Scientists also revealed in 2021 that they’d detected traces of methane gas in the moon’s plumes that could be coming from live microbes. 

Even the highest possible estimate of ‘abiotic’ methane (not produced by living organisms) is not enough to explain the methane concentration in the plumes, the team said at the time.

And in June 2023, German scientists revealed the presence of phosphates – a key element for the existence of life – in the ocean water. 

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