Titan’s subsurface ocean and similar oceans inside other outer icy moons solar systemmay not have the organic chemistry required for lifeaccording to new astrobiological research.
Titan Saturn‘s largest moon and the second largest moon in the entire solar system. It is famous for being covered in a smog of petrochemicals and having a veritable soup of organic molecules (carbon-containing molecules) on its surface. But for all this fascinating chemistry, Titan is cold. Very cold. Surface temperatures are no warmer than -179 degrees Celsius (-290 degrees Fahrenheit). And in these cold conditions, the chemical reactions of life proceed very slowly.
However, deep underground, where the air is warmer – the exact depth is uncertain, but estimates suggest it is on the order of 100 kilometers (62 miles) – is a liquid ocean 12 times its volume. Earth’s oceans The combination is thought to exist. Similar oceans live in the interior of Saturn’s other moon, Titan EnceladusAnd Jupiter‘S Months Europe And in the booty.
Relating to: Subsurface ocean tides on Saturn’s moon Titan are influenced by its icy crust
Where there is liquid water, there can be life. Right? Not so fast, says Catherine Neish of Western University in Ontario, Canada.
Neish, a planetary scientist, led an international team that challenged the assumption that Titan’s ocean, and indeed the oceans of other icy moons, might be habitable.
The researchers worked on the basis that for Titan’s ocean to be habitable, large amounts of organic molecules from the surface must be physically able to reach the ocean to facilitate prebiotic chemistry that can produce and nourish life.
The way this organic matter reaches the ocean is as follows: comet effects. Such impacts can melt surface ice, creating a pool of liquid water filled with organic molecules. Liquid water sinks because it is denser than ice. But Neish’s modeling found that the impact rate was not high enough for enough organic matter to reach Titan’s ocean.
For example, Neish’s team estimates that only 7,500 kilograms (16,534 pounds) of the simplest amino acid, glycine, reaches Titan’s ocean each year. That may sound like a lot, but that’s equivalent to the mass of a male African elephant spanning an ocean a dozen times the volume of Earth’s oceans. That’s not even a drop in the ocean, if you’ll excuse the pun.
“We assumed that the majority (65%) of the melt deposits would sink all the way to the ocean,” Neish told Space.com. “Recent modeling studies suggest this is likely an overestimation, but even in this most optimistic scenario not enough organic matter is transported into Titan’s ocean to support life there.”
There may be other possibilities. On Europa, which has very few organic molecules on its surface, hydrothermal vents It may exist on the seafloor where the ocean contacts the moon’s rocky core. These holes would repel all kinds of molecules and trigger complex chemical reactions that could support life. More evidence of carbon in Europe’s ocean has been discovered. James Webb Space Telescope. JWST defined Carbon dioxide rising from the ocean to Europa’s surface.
So could the same thing happen on Titan, with organic matter coming from the Moon’s interior rather than its surface?
Neish doesn’t rule it out, saying colleagues like Kelly Miller of the Southwest Research Institute in San Antonio, Texas, are exploring the possibility; But Neish emphasizes a particular caveat.
“One of the concerns that has arisen is whether organics from the interior would be beneficial to life,” he said. “We think these may be primarily aromatic compounds, and we think it is difficult to create biomolecules such as amino acids from such compounds.”
While we’re still some way away from being able to directly probe the oceans of these icy moons and say for sure whether they contain life, Neish’s research reveals some promising opportunities for life. NASA‘S dragonfly mission To Titan, where Neish is a co-investigator.
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Dragonfly is a helicopter mission partially inspired by Creativity Anthem the one with the helicopter Planned to be released in 2028 About to arrive on Titan in 2034. To be discovered moon from the air, landing on the ground to collect samples for analysis. If Neish’s work is correct, this could mean there could be many impact points on the surface where liquid water mixes with organic matter, possibly igniting some complex chemistry before refreezing and sinking. By examining these sites, scientists may learn more about prebiotic chemistry This led to the emergence of life on Earth.
Neish’s team’s findings were published Feb. 2 in the journal. Astrobiology.