Saturn’s giant moon bears another odd resemblance to Earth

(ORDO NEWS) — Compared to most places one would travel to in the solar system, Titan – Saturn’s giant moon – is strangely familiar to Earth in many ways.

In fact, Titan is the only moon in the solar system with a dense atmosphere, providing a range of quasi-terrestrial weather events such as methane showers that feed rivers and, in turn, lakes.

Although Titan’s landscape is in many ways unlike Earth’s, other aspects of the icy moon are not all that different, such as Titan’s towering sand dunes – and yet the existence of these dunes is something of a mystery.

On Earth, the sedimentary material that makes up sand dunes is made up of inorganic silicates, but the chemistry of Titan’s sand is quite different.

“Sedimentary rocks on Saturn’s moon are believed to be composed primarily of mechanically weak organic grains that are prone to rapid abrasion into dust,” a team of scientists led by planetary geologist Mathieu Lapautre of Stanford University explains in the new study.

This rapid abrasion means that over time, the sand particles in Titan’s dunes must become finer and finer until they eventually turn to dust.

This light dust will eventually become so fine that it escapes into the atmosphere and fails to form solid structures like giant dunes that require larger particles to coalesce.

“When the winds carry the grains, they collide with each other and with the surface,” says Lapotre. “These collisions tend to decrease in grain size over time.”

But due to Titan’s huge sand dunes, researchers speculate that some unknown growth mechanism is at work on the Moon, capable of strengthening the grains and resisting the forces of abrasion.

Whatever it is, it’s been happening for a very long time.

“Titan’s equatorial dunes have likely been active for [tens to hundreds of thousands of years],” the team wrote. “To maintain the dunes of Titan over geologic time, a mechanism is needed that produces sand-sized particles at equatorial latitudes.”

In a new study, scientists speculate what this mysterious mechanism might be, inspired by the existence of ooids, small, rounded sedimentary grains found on the Earth’s seafloor.

Unlike most other forms of sand (usually formed by abrasion), ooids are accretionary formations that form from smaller particles through chemical precipitation in the marine environment.

According to the researchers’ simulations, a similar phenomenon could explain the existence of organic deposits on Titan.

This allows the particles to sinter (compact) into coalesced lumps, counteracting the simultaneous force of abrasion and maintaining the particles in an equilibrium size.

“This readily allows for the formation of active sand dunes at equatorial latitudes, with some dust production but no significant dust accumulation due to sintering of dust grains into sand over time,” the researchers explain, noting that their calculations also explain the existence of characteristic sandstone formations. on the plains of the moon and at its poles.

“On Titan – as on Earth, and as it used to be on Mars – we have an active sedimentation cycle that can explain the latitudinal distribution of landscapes by episodic attrition and sintering driven by the seasons on Titan,” says Lapoutre.

While the team admits that their explanation of the sedimentary cycle on Titan is only a hypothesis so far, since other scenarios cannot be completely ruled out, they are confident that it is consistent with what we see on this strangely familiar moon, which was once called “an abnormal version of Earth.”

“We were able to resolve the paradox of why sand dunes could exist on Titan for so long, despite the fact that the materials are very weak,” says Lapotre.

“It’s very exciting to think that there is an alternate world so far out there where everything is so different yet so similar at the same time.”

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