[ad_1]
Posted Sep 14, 2018
During the last distant encounter of NASA's Cassini mission with Titan, the giant moon of Saturn, the spacecraft captured this view of the northern polar landscape of lakes and seas, filled with liquid methane and ethane containing organic molecules that could possibly be inhospitable. conditions, form structures similar to lipid bilayers of living cells on Earth.
Punga Mare (390 kilometers across) is visible just above the center of the mosaic, with Ligeia Mare (300 miles or 500 kilometers wide) under the center and the vast Kraken Mare which stretches for 1200 kilometers the left of the mosaic. Many small Titan lakes can be seen around the seas and scattered on the right side of the mosaic. Among the current mysteries concerning Titan, there is the formation of these lakes.
Another mystery to Titan was the weather. With its dense atmosphere, Titan has a methane cycle very close to the Earth's water cycle, namely evaporation, cloud formation, precipitation, surface runoff in rivers, and lake collection. and the seas. During the southern summer of Titan, Cassini observed cloud activity over the South Pole.
However, typical of northern spring and summer observations, the view reveals only a few small clouds. They appear as bright lines just below the center of the mosaic, including a few above Ligeia Mare.
The images of this mosaic were taken with the narrow-angle camera of the ISS, using a spectral filter sensitive to wavelengths of near 938 nanometers infrared light captured on September 11, 2017 during the Cassini's last meeting with Titan. Four days later, Cassini was deliberately immersed in the atmosphere of Saturn.
In 2015, scientists wondered whether organic molecules likely to be on Titan could, under inhospitable conditions, form structures similar to the lipid bilayers of living cells on Earth. Thin and flexible, the lipid bilayer is the main component of the cell membrane, which separates the inside of a cell from the outside world. This team has identified acrylonitrile as the best candidate.
These researchers proposed that acrylonitrile molecules could combine into a sheet of material similar to a cell membrane. The leaf could form a hollow microscopic sphere that they have dubbed "azotosome". This sphere could serve as a tiny storage and transport container, just like the spheres that can form lipid bilayers.
The Goddard team has determined that acrylonitrile is abundant in Titan's atmosphere, present at concentrations of up to 2.8 parts per billion. The chemical is probably the most abundant in the stratosphere, at altitudes of at least 125 miles (200 kilometers). Finally, acrylonitrile heads to the cold, cold atmosphere where it condenses and rains on the surface.
The researchers calculated the amount of material that could be deposited at Ligeia Mare, Titan's second largest lake, which is about the same size as Lake Huron and Lake Michigan. During Titan's lifetime, the team estimated that Ligeia Mare could have accumulated enough acrylonitrile to form about 10 million nitrogens in each milliliter or quarter of a teaspoon of liquid. This compares to about one million bacteria per milliliter of coastal ocean water on Earth.
Cassini made hundreds of passes over Titan during her 13-year tour of the Saturn system, including 127 precisely targeted encounters, some at short distances and some, like this one, more distant.
Cassini completed her 13-year tour of the Saturn system with an intentional dive into the planet to ensure that Saturn's moons – particularly Enceladus, with its ocean below the surface and signs of hydrothermal activity – remain intact for future exploration. The fateful dive of the craft was the last stage of the grand final of the mission, 22 weekly dives in the gap between Saturn and its rings. No spacecraft had ever ventured as close to the planet before.
The Daily Galaxy via the Jet Propulsion Laboratory and the Goddard Spaceflight Center
Image Credit: NASA / JPL-Caltech / Space Science Institute
Top 10 Space & Science Titles from 2018
"Spy on the world's most awesome creatures" – Scientists pursue undiscovered whale species
The Extraterrestrial Observatory – "When we see something unusual, it's gaping, it can be a sign of life"
Point of No Return researcher predicts Horizon event for Earth's sixth mass extinction
Artificial intelligence already exists and it's billions of years "(WATCH Video)
The "ghost signals" of extraterrestrial civilizations haunt the milky way – suggests the new equation of Drake (WATCH the video)
"Chances are there's never been another civilization in the universe, one out of ten billion billion" – Interview with Joe Rogan
The Alien Observatory – "The mystery of extraterrestrial life is hiding"
"We are entering an unknown territory" – The exoplanets revolution could reveal that the rise of civilizations might not be unusual
"The Big Rip" – When matter and space-time are gradually torn apart by the expansion of the universe
"Humans are the first to arrive at the interstellar stage" – The physicist responds to the Fermi paradox
[ad_2]
Source link
