Tidal Currents between Titan’s Seas Detected by Solar Glints

Monday, 14 December 2015: 11:05
2007 (Moscone West)
Christophe Sotin1, Jason W Barnes2, Kenneth J Lawrence1, Jason M Soderblom3, Edward Audi4, Robert Hamilton Brown5, Stephane Le Mouelic6, Kevin H Baines7, Bonnie J Buratti1, Roger Nelson Clark8 and Phil d Nicholson9, (1)NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, United States, (2)University of Idaho, Moscow, ID, United States, (3)Massachusetts Institute of Technology, Earth, Atmospheric, and Planetary Sciences, Cambridge, MA, United States, (4)University of Arizona, Planetary Sciences and Astronomy, Tucson, AZ, United States, (5)University of Arizona, Tucson, AZ, United States, (6)University of Nantes, Nantes, France, (7)Jet Propulsion Laboratory, Pasadena, CA, United States, (8)Planetary Science Institute Tucson, Tucson, AZ, United States, (9)Cornell University, Dept. of Astronomy, Ithaca, NY, United States
Titan is the only place in the solar system, besides Earth, to have stable bodies of liquids on its surface. The three large seas and most of the lakes are located in the northern pole area [1]. They are major reservoirs of organic material [2]. Questions related to the variability in composition of the seas [2] and their interaction [3] can be addressed by dedicated observations. For this purpose, the Visual and Infrared Mapping Spectrometer (VIMS) observed the area between Ligeia Mare and Kraken Mare, Titan’s two largest seas on February 12, 2015. The location of the specular point was close to the strait that has been suggested to link Ligeia and Kraken [4]. As demonstrated by previous observations of specular reflections on the lakes and seas [5, 6], such observations provide a means to assess the presence of liquids and the dynamics of the liquid surface.

The VIMS observation provides images of the strait, named Trevize fretum, with a footprint of about 3 km. It shows a remarkable correlation with the radar images, suggesting that no major changes in the level of the seas have occurred in the last 10 years, a third of a Titan year. Very strong values of I/F at 5-μm suggest specular reflection away from the specular point on the Ligiea outlet. This is consistent with the presence of waves which can be generated by either winds or strong currents between Kraken Mare and Ligeia mare. Such currents can be generated during Titan’s orbital motion around Saturn. We have investigated the volume of liquids that would transit through Trevize fretum during a Titan day and have found that the flow would be in a turbulent regime for the value of the mean anomaly at the time of the VIMS observation. Although subsurface communication between the two seas cannot be ruled out, the present observation underlines the role of the strait in providing exchange of fluids between the two large seas.

This work has been performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract to NASA.

[1] Stofan et al. (2007) Nature, 445, 61–64. [2] Lorenz et al. (2014) Icarus, 237, 9-15. [3] Tokano et al. (2014) Icarus, 242, 188-201. [4] Sotin et al. (2014), AGU, P43C-3999. [5] Soderblom et al. (2012) Icarus, 220, 744-751. [6] Barnes et al. (2013) Astrophysical J., 777, 161.