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Are organic crystals forming "tub rings" around Titan's lakes and seas? | space

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  Green ball with irregular dark green, orange and yellow markings in the upper part.

Infrared image of seas and lakes in the northern hemisphere of the Titan, taken by Cassini in 2014. The sunlight shines from the southern part of Titan's largest sea, Kraken Mare. Scientists now believe that "bath rings" at the edges of seas and lakes consist of organic crystals. Image via NASA / JPL-Caltech / University of Arizona / University of Idaho / AGU 100.

The Saturn moon Titan is the only other body in the solar system next to the Earth that is known to have fluids on its surface. These rains, rivers, lakes and seas are similar to those on Earth, but consist of liquid methane and ethane (hydrocarbons) instead of water. Now scientists have come up with a different way of distinguishing themselves from their earthly counterparts: the shores of lakes and oceans could be covered with "tub rings" of organic crystals that were not found on Earth.

The new study was published in A New Paper, which was presented on June 24 at the Astrobiology Science Conference 2019 (AbSciCon 2019) in Bellevue, Washington.

From the New Paper:

We have discovered a third molecular mineral that is stable under the same conditions as the surface of Titan, a moon of Saturn. This molecular mineral consists of acetylene and butane, two organic molecules that are generated in the titanium atmosphere and fall to the surface. We call these "molecular minerals" because they behave just like minerals here on Earth, but instead of being made of things like carbonates or silicates, they are made up of organic molecules. The two previously discovered molecular minerals consisted of benzene and ethane as well as acetylene and ammonia. This latest one is likely to be much more common on the titanium surface, as both acetylene and butane are considered to be very common there. In particular, we believe that the "tub rings" around Titan's lakes could be made of this material because acetylene and butane dissolve well in liquid methane and ethane compared to other molecules.

  Steep mountains surround the reddish lake under faint, pale light tan sky.

Artist concept of a hydrocarbon lake on the Titan seen from the ground. Picture about Steven Hobbs (Brisbane, Queensland, Australia / NASA).

The intriguing results are from laboratory tests that restored titan-like conditions. The scientists found compounds and minerals that do not exist on Earth, and a co-crystal was made from solid acetylene and butane that exist on Earth, but only as gases. However, titanium is so cold that acetylene and butane become solid and combine to form crystals.

How did the scientists create titanium-like conditions in a laboratory on Earth? Titan is extremely cold, about -290 degrees Fahrenheit (-179 degrees Celsius), so they used a custom built cryostat, a device that keeps things cold. The Titan atmosphere is mostly nitrogen, like Earth's. Next, they filled the cryostat with liquid nitrogen. But they needed the nitrogen to be a gas, like on the Titan, so they warmed the chamber slightly. Subsequently, methane and ethane were added, which are also very common in titanium. They are both in liquid form on the moon, in the rain, in rivers, lakes and seas. The result was a hydrocarbon-rich "soup".

  Dark blue, irregular shapes with labels against a light brown background.

Map of the seas and lakes of the Titan in the northern hemisphere. Image via JPL-Caltech / NASA / ASI / USGS / EarthSky.

  Yellowish scene with blurred sky and landscape, covered with rounded, irregular rocks.

The surface of the Titan, seen from the Huygens Lander in 2005. Huygens found damp sand when he landed near a vaporized riverbed. The liquid was methane / ethane, but the "rocks" consisted of solid water ice. Image via ESA / NASA / University of Arizona / EarthSky.

Benzene crystals were the first to form in this soup. Benzene occurs in petrol on Earth and is a snowflake-shaped molecule consisting of a hexagonal ring of carbon atoms. However, under the simulated Titan conditions, something surprising happened: the benzene molecules rearranged to take up ethane molecules and form a co-crystal. Later, the researchers also discovered an acetylene and butane crystal, which is believed to be more common on Titan.

It is the acetylene and butane crystals that are likely to form the tub rings – vaporized minerals – around the tub edges of the lakes and seas. The minerals would fall out at the surface as the liquid hydrocarbons start to evaporate. Some lakes were seen by the Cassini spaceship on the Titan when they were filled with liquid, and at other times when they partially evaporated. This evaporation process is similar to the way salts can form crusts on the edges of lakes and seas on Earth.

Titan's bathtub rings are believed to exist from Cassini's evidence, but have not yet been fully confirmed by Morgan Cable at the Jet Propulsion Laboratory:

We do not yet know if we have these bathtub rings … It's hard to get through Titans to see a hazy atmosphere.

<img aria-describedby = "caption-attachment-316567" class = "size-large wp-image-316567" src = "https://en.es-static.us/upl/2019/07/salt -lake-beacon-western-Australia-800×457.png "alt =" Wide white band surrounding the whitish lake under a bright blue sky. [19659022] An acid salt lake south of Beacon, Western Australia Borders resemble bathtub rings on the edges of lakes and seas on Titan Image via Suzanne M. Rea / ResearchGate.

Titan's rivers, lakes and seas, mostly near the North Pole, give this moon a sinister earth-like appearance There are also methane rain and massive sand dunes near the equator, as in desert areas on Earth, but made up of hydrocarbon particles, and the thick, murky atmosphere obscures the ground from above, but Cassini detected radar surface features Cassini mission, sent 2005 auc The first photos from the surface of the Titan showed a vaporized riverbed with "stones" of solid water ice. Under all this, an underground water ocean is invisible. Titan may in many ways be very similar to Earth but in its composition it is a very strange world.

Unfortunately, Cassini's mission ended in late 2017, so further observations of the bathtub rings will follow. I have to wait for a future mission to return to Titan. Probes that could swim or swim in one of the lakes or oceans have been proposed, but are still on the drawing boards. However, NASA's new Dragonfly mission, which was officially announced just last week, will send a drone-type rotary wing aircraft to fly through Titan's sky and make numerous landings in various locations of interest. The launch of the dragonfly is planned for 2026 and the landing for 2034. Exciting! Conclusion: By simulating the conditions of titanium in a laboratory on Earth, scientists have discovered that unusual forms of organic crystals can form bath rings at the edges of the lunar lakes and oceans.

Source: The Acetylene-Butane Co-Crystal: A Potentially Common Molecular Mineral on Titanium

Via AGU 100

  Paul Scott Anderson

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