by Titan’s underground ocean, and similar oceans inside other icy outer moons Solar systemcould lack the organic chemistry necessary for lifeaccording to new astrobiological research.
There is a Titan Saturnthe largest moon, and the second largest moon in the entire solar system. It is famous for being shrouded in petrochemical smog and for having a veritable soup of organic molecules – molecules that contain carbon – on its surface. But, despite all this great chemistry, Titan is cold. Very cold. It has a surface temperature no hotter than -179 degrees Celsius (–290 degrees Fahrenheit). And in these frigid conditions, chemical reactions for life progress very slowly.
However, deep underground where it is warmer – the exact depth is not certain, but estimates suggest it is about 100 kilometers (62 miles) – a liquid ocean with a volume 12 times greater than . Oceans of the World It is considered to be combined. Similar oceans occupy the interior of Titan’s other moon Enceladusand Jupiterand moons Europe and Ganymede.
Related: Saturn’s moon Titan is influenced by its icy crust on the tides of an underground ocean
And where there is liquid water, there may be life. Right? Not so fast, says Catherine Neish of Western University in Ontario, Canada.
Neish is a planetary scientist, leading an international team that challenged the assumption that Titan’s sea, and indeed other icy moon oceans, could be habitable.
The researchers worked on the premise that for Titan’s ocean to be habitable, a large supply of organic molecules from the surface must be able to physically reach the ocean in order to produce and sustain prebiotic chemistry to facilitate.
It is the way for this organic matter to reach the ocean comet influences. Such impacts can melt surface ice, creating a pool of liquid water filled with organic molecules. Because liquid water is denser than ice, it sinks. But, Neish’s modeling found that the impact rate is not high enough for enough organic matter to reach Titan’s ocean.
For example, Neish’s team estimates that only about 7,500 kilograms (16,534 pounds) of the simplest amino acid, glycine, reach Titan’s oceans each year. It may sound like a lot, but that’s equivalent to the mass of one African elephant spread over an ocean a dozen times the volume of Earth’s oceans. If you excuse the point, it’s hardly a drop in the ocean.
“We assumed that most of the melt deposits – 65% – would sink all the way to the ocean,” Neish told Space.com. “Recent modeling work suggests that this is likely an overestimate, but even in this most optimistic scenario, not enough organisms are moving into Titan’s ocean to support life there.”
There could be other possibilities. On Europa, where there are very few organic molecules on the surface, it has been postulated that it is hydrothermal vents it could be on the sea floor where the ocean meets the rocky core of the moon. These vents would spew all kinds of molecules and trigger complex chemical reactions that could support life. Further evidence of carbon in Europa’s oceans has been found by the James Webb Space Telescope. Recognized by the JWST carbon dioxide that has risen from the ocean to Europa’s surface.
So, could the same thing happen on Titan, with organic matter coming from inside the moon, rather than from its surface?
Neish doesn’t rule it out, saying that colleagues like Kelly Miller at the Southwest Research Institute in San Antonio, Texas, are investigating the possibility—but Neish emphasizes one particular caveat.
“One concern that has arisen is whether the organisms found inside would be useful for life,” she said. “We think they are mainly aromatic compounds, and it is difficult to form biomolecules – such as amino acids – from such compounds.”
While we’re still some ways away from being able to directly explore the oceans of these icy moons to tell for sure whether or not they harbor life, Neish’s research holds some promising opportunities for NASAand Dragonfly mission a Titan, on which Neish is a co-investigator.
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Dragonfly is a helicopter mission, inspired in part by the Intellect Mars a helicopter, that is planned to launch in 2028 about reaching Titan in 2034. He will explore the moon from the air, touching down to take samples for analysis. If Neish’s work is correct, it would mean that there could be many impact sites on the surface where liquid water mixes with organisms, which could spark some complex chemistry before refreezing and submerging. By studying these sites, scientists could learn more about prehistoric chemistry which went all the way to form life on Earth.
The results of Neish’s team were published on February 2 in the journal Astrobiology.
