Saturn’s moon Titan has ice on the surface of hydrocarbon lakes and seas

Researchers from NASA’s Cassini mission found blocks of hydrocarbon ice on the Saturn’s moon Titan showing that some form of extra-ordinary life might be present in that environment.

“One of the most intriguing questions about these lakes and seas is whether they might host an exotic form of life,” said Jonathan Lunine, a paper co-author and Cassini interdisciplinary Titan scientist at Cornell University, Ithaca, N.Y. “And the formation of floating hydrocarbon ice will provide an opportunity for interesting chemistry along the boundary between liquid and solid, a boundary that may have been important in the origin of terrestrial life.”

Artist's depiction of ice on hydrocarbon sea on Titan (Credit: credit: NASA/JPL-Caltech/USGS)

Titan is the only object in the solar system after Earth that has liquid on its surface but that liquid is made up of hydrocarbons like ethane and methane, which are considered as the building blocks for the life. Researchers, utilizing Cassini, found hydrocarbon seas in the Titan’s northern hemisphere and the lakes in the southern hemisphere.

This research is contrary to the previous beliefs that floating ice is not present on Titan lakes because of the higher density of solid methane than the liquid methane that results in the sinking of the ice. But the new model shows that due to the interaction between the lakes and atmosphere, different mixtures of compositions, pockets of nitrogen gas and changes in temperature, Titan’s methane and ethane rich lakes and seas could have floating ice, if the temperature is below the freezing point of methane i.e. minus 297 degrees Fahrenheit (90.4 kelvins). Scientists have found that all the varieties of ice would float, if they have at least 5% of air. Although the color of the ice has not been figured out but it is considered to be colorless with reddish-brown tints due to the Titan’s atmosphere.

“We now know it’s possible to get methane-and-ethane-rich ice freezing over on Titan in thin blocks that congeal together as it gets colder — similar to what we see with Arctic sea ice at the onset of winter,” Jason Hofgartner, first author on the paper and a Natural Sciences and Engineering Research Council of Canada scholar at Cornell, said in a statement. “We’ll want to take these conditions into consideration if we ever decide to explore the Titan surface some day.”

“Cassini’s extended stay in the Saturn system gives us an unprecedented opportunity to watch the effects of seasonal change at Titan,” said Linda Spilker, Cassini project scientist at NASA’s Jet Propulsion Laboratory, Pasadena, Calif. “We’ll have an opportunity to see if the theories are right.”

Appendix:

What is the amount of oxygen on Titan?

“Air” on Titan is without oxygen and has more nitrogen than Earth.

How Cassini worked for the above model?

Cassini’s radar system worked by checking the reflectivity of the surface of the lakes and seas, as the ice rises to the surface, the surface becomes more reflective sending more radio energy back to the Cassini making it to look brighter. In warmer weather as the ice melts, the lake surface becomes liquid, and the reflections become darker.