Titan is the largest moon of Saturn and receives only about 1% of the amount of solar energy Earth does. Thus, the average surface temperature is extremely low, about 90.6 K (-182.55 °C, or -296.59 °F). Under this extremely cold temperature, Titan’s atmosphere is nearly free of water vapor, and is primarily composed of nitrogen and methane. At the surface level, the cold temperature and the high pressure (~ 1.5hPa) allows methane to stay in liquid form (i.e., boiling at -164 °C, and melting at -182 °C). Titan’s largest sea of liquid methane, Kraken Mare, is about the size of Black Sea and is located in Titan’s north polar region. In a new paper published in the Journal of Geophysics Planets, astronomers at Cornell University analyzed radar altimeter data from Cassini, the fourth space probe mission to Saturn, during 2013 – 2017. Their analysis showed no evidence for signal returns from the sea floor, suggesting the liquid is too deep for Cassini’s radio waves to penetrate. Given the liquid composition in the main body of Kraken Mare that is largely methane, this suggests that the depth exceeds 100 m. This estimate is compatible with a separate estimate using the radar as a radiometer, sensing thermal energy from the sea at radio wavelengths. The research team hopes to see a future mission to visit and cruise Kraken Mare using an unmanned submarine vessel. Given that Titan represents a possible environment of early Earth, could there be life in Titan’s methane sea?
Image Credit (NASA JPL-Caltech): This is artist’s concept of a sea of liquid methane at the north pole of Titan.
Poggiali, V., Hayes, A. G., Mastrogiuseppe, M., Le Gall, A., Lalich, D., Gómez‐Leal, I., & Lunine, J. I. (2020). The bathymetry of moray sinus at Titan’s Kraken Mare. Journal of Geophysical Research: Planets, 125, e2020JE006558. https://doi.org/10.1029/2020JE006558