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July 23 news, seven years ago, NASA'sCassiniNumberSaturnThe probe dramatically ended its 20-year mission to explore Saturn and its moons when it plunged into the gas giant.planet. However, it still continues to provide scientific research results.

Cornell University astronomers used radar data collected by Cassini to obtain new information about Saturn's largest moon.TitanThe new information comes from a liquid ocean on Earth's surface that is made up mostly of hydrocarbons such as methane and ethane.

The research team analyzed the composition and "roughness" of the ocean near Titan's north pole. They found an ocean filled with calm methane water and gentle tidal currents. This is a phenomenon that has not been revealed in previous studies of Titan's ocean, and it also provides a basis for future studies of Titan's ocean.Solar SystemThis laid the foundation for more in-depth research on ocean satellites.

Data for the new findings were collected using "ballistic radar" used by Cassini, a technique that involves the probe sending a radio beam toward Titan, which is then reflected back to Earth.

This method creates a polarization effect on Titan's surface reflections, allowing two different views of the surface, providing additional data beyond a single view compared to standard radar, which only sees signals reflected back to Cassini.

"The key difference is that the two perspectives provide a more comprehensive dataset that accurately captures the composition of the reflective surface and its roughness," said Valerio Poggiali, a researcher at Cornell University's Center for Astrophysics and Planetary Science.

Cassini was launched on October 15, 1997, and it took seven years to reach the Saturn system. In 2017, NASA chose to have Cassini collide with Saturn to prevent the probe from eventually hitting one of Saturn's 146 known moons.

The ballistic radar data used by Poggiari and his colleagues were collected during four flybys of Titan by Cassini on May 17, June 18, October 24, 2014, and November 14, 2016. During these flybys, scientists observed reflections from the surface when Cassini was closest to Titan and when it was moving away.

The researchers looked at Titan's three polar seas: Kraken Mare, Lygia Mare and Ponga Mare. They found that the composition of the surface layers of these hydrocarbon seas varies depending on location and latitude, with material in the southernmost part of Kraken Mare being the most efficient at reflecting radar signals.

When Cassini observed Titan's three seas, they all appeared calm, with the spacecraft recording wave heights of about 3.3 millimeters. Where the hydrocarbon ocean meets the coast, wave heights reached 5.2 millimeters, indicating the presence of weak tidal currents.

"We also observed that the rivers flowing into these oceans were pure methane before they entered the open liquid ocean, while these oceans were enriched in ethane," Poggiari added. This is similar to what happens on Earth when freshwater rivers flow into and mix with the salty water of the ocean.

The finding is consistent with meteorological models of Titan, which predict that rainfall on Titan is mostly methane, with small amounts of ethane and other hydrocarbons.

Poggiari also said the team will continue to study the data produced by Cassini during its 13 years of observing Titan. "There is a lot of data waiting for us to fully analyze it with new methods, which should lead to more discoveries." He concluded: "This is just the beginning."

The team's research results were published in the journal Nature Communications last Tuesday (July 16).