Scientists have published a new study that concludes Saturn's moon Titan might have ice floating in its seas. The presence of hydrocarbon ice in Titan's methane lakes and seas could explain the mixed readings NASA's Cassini probe has seen while recording the reflectivity of the moon's surface.
"One of the most intriguing questions about these lakes and seas is whether they might host an exotic form of life," said Jonathan Lunine, co-author of the research and a Cassini interdisciplinary Titan scientist at Cornell University. "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."
Floating methane ice was thought to be impossible on Titan, since solid methane is more dense than liquid methane, and would sink. The new research considers the interplay between Titan's lakes and the moon's atmosphere. Scientists found that the types of methane and ethane ice that might exist on Titan will float if the temperature is below 90.4 kelvins (297 degrees Fahrenheit), methane's freezing point.
"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," said Jason Hofgartner, lead author of the paper and a Natural Sciences and Engineering Research Council of Canada scholar at Cornell. "We'll want to take these conditions into consideration if we ever decide to explore the Titan surface some day."
Titan is the only other object in our solar system besides Earth known to have bodies of liquid on its surface. Its seas are composed of organic molecules that are believed to have been the building blocks for life on Earth.