ALIEN life could be hiding away on the vast ocean of a nearby moon.
Scientists say there's a chance that a “small population” could be tucked away on Titan, the biggest of Saturn's moons.
have long suspected that life-forms could survive on a Saturn moon.
And icy Titan is a good candidate due to the ocean concealed beneath its “thick, hazy atmosphere”.
The University of Arizona describes it as “covered in rivers and lakes of liquid methane, icy boulders and dunes of soot-like ‘sand”.
And space scientists there now say that the planet could support “a few pounds of biomass”.
This would be “simple, microscopic life” rather than the walking, talking extraterrestrials we see in sci-fi movies.
It means Titan could be the perfect place to probe for alien life – as it's not very far away, in terms of space.
“In our study, we focus on what makes Titan unique when compared to other icy moons: its plentiful organic content,” said Antonin Affholder, of the University of Arizona.
The team found that the subsurface ocean on Titan – around 300 miles deep – could support “life-forms that consume organic material”.
The planet is described as being “Earth-like on the surface”, but it's the ocean where life is suspected to be lurking.
Sadly, there wouldn't be much of it – and it might be hard to track down.
“There has been this sense that because Titan has such abundant organics, there is no shortage of food sources that could sustain life,” Affholder explained.
“We point out that not all of these organic molecules may constitute food sources, the ocean is really big.
“And there's limited exchange between the ocean and the surface, where all those organics are, so we argue for a more nuanced approach.”
Part of the study involved working out how life could persist on Titan.
And the scientists think that the moon's life might make use of a common process: fermentation.
On Earth, fermentation is used for brewing or making a sourdough – and importantly only requires organic molecules, but no oxidant (like oxygen).
“Fermentation probably evolved early in the of Earth's life,” explained Affholder.
“And does not require us to open any door into unknown or speculative mechanisms that may or may not have happened on Titan.
“We asked, could similar microbes exist on Titan?
“If so, what potential does Titan's subsurface ocean have for a biosphere feeding off the seemingly vast inventory of abiotic organic molecules synthesised in Titan's atmosphere, accumlating at its surface and present in the core?”
One organic molecule called glycine is the simplest amino acid.
And it's abundant in our Solar System, which is a plus.
“We know that glycine was relatively abundant in any sort of primordial matter in the solar system,” Affholder said.
“When you look at asteroids, comets, the clouds of particles and gas from which stars and planets like our solar system form, we find glycine or its precursors in pretty much all those places.”
Scientists ran computer simulations that revealed how just a tiny fraction of Titan's organic material could be gobbled up by microbes.
They'd need a steady stream of glycine from the surface, through Titan's thick icy shell.
This could be delivered by melt pools of water – created by meteorites hitting the ice – that sink down, bringing surface material to the ocean below.
“Our new study shows that this supply may only be sufficient to sustain a very small population of microbes,” said Affholder.
“Weighing a total of only a few kilograms at most—equivalent to the mass of a small dog.
“Such a tiny biosphere would average less than one cell per liter of water over Titan's entire vast ocean.”
Sadly that means that finding life on Titan could be like looking for a needle in a haystack, scientists say.
But there is a plan to probe Titan already: ‘s .
It's set to launch no earlier than July 2028, trawling the alien world in the name of .
Nasa explains: “In a voyage straight out of , Dragonfly will deliver the most expansive suite of science instruments ever dispatched to another celestial body.
“ will cover more than 50 miles of the organics-rich Titan surface.
“Landing, collecting and returning results that could change our understanding of life in the universe.”
The research was published in The Planetary Science Journal.
