Rain, sea and surface of erosive organic matter are found both on the ground and on Saturn's largest moon, Titan. But on Titan it is methane, not water that fills the lakes with slushy raindrops.
While trying to find the source of Titan's methane, the University of Arizona's researcher Caitlin Griffith and her team discovered something unspecified ̵
Griffith, a professor of UA Lunar and Planetary Laboratory, is the lead author of the paper published today in Nature Astronomy .
On Titan, atmospheric methane molecules are continuously broken by sunlight. The resulting atmospheric haze settles to the surface and accumulates as organic sediments which rapidly degrade the atmospheric methane.
This organic veneer consists of the material from previous atmospheres.
There is no apparent source of methane except for the evaporation of methane from the polar sows. But Titan's lakes contain only a third of methane in Titan's atmosphere and will soon be exhausted by geological time scales.
One theory is that the methane could be supplied by underground reservoirs that emit methane into the atmosphere. Earlier Titan studies indicate the presence of a unique region called Sotra, similar to the cryo volcano, with icy flow functions.
Griffith's team set out to study the composition of Titan's surface, hoping in part to find subtle small cryo-volcano candidates. They analyzed half of Titan's surface and no one was detected, but Sotra turned out to be exceptional, showing the strongest ice properties.
But the great ice function that the researchers found was completely unexpected. It consists of a linear ice corridor that wraps around 40 percent of Titan's perimeter.
"This icy corridor is enigmatic because it does not correlate with surfaces or measurements of the subsoil," Griffith said. "Given that our study and past work show that Titan is currently not volcanically active, the corridor trail is probably a past past. We discover this feature on steep slopes, but not on all slopes. icy corridor is currently eroding, possibly revealing the presence of ice and organic layers. "
The team's analysis also shows a variety of organic matter in some regions. These surface deposits are of interest because laboratory simulations of Titan's atmosphere produce biologically interesting compounds such as amino acids.
Griffith analyzed tens of thousands of spectral images taken from the top layer of the surface of Cassini's Synible and Infrared Mapping Spectrometer using a method that enabled the detection of weak surface properties.
This effect was performed by Griffith's use of the main component assay or PCA. It allowed her to justify subtle functions caused by ice and organic sediments on Titan's surface from the ubiquitous drop and clearer surfaces. Instead of measuring the surface functions individually for each pixel in an image, PCA uses all of the pixels to recognize the most important and subtle signatures.
Griffith's team compared their results to previous studies, including Huygens probe, which landed on Titan in 2005. The comparison validated both the technique and the results. There are plans to use the technology to explore the poles where the metaseas lie.
"Both Titan and Earth followed various evolutionary paths, and both ended with unique organic rich atmospheres and surfaces," Griffth said. "But it is not clear whether Titan and Earth are common drawings of organically rich bodies or two among many possible organic rich worlds."
See Titan with infrared eyes
A corridor of exposed hard rock across Titan's tropical region, Nature Astronomy (2019). DOI: 10,1038 / s41550-019-0756-5, https://www.nature.com/articles/s41550-019-0756-5
Scientists find ice function on Saturn's giant moon (2019, April 29)
April 29, 2019
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