Bubble streams in Titan’s seas as a product of liquid N2 + CH4 + C2H6 cryogenic mixture


Titan, Saturn’s largest moon, is the only extraterrestrial body known to support stable liquid on its surface, in the form of seas and lakes that dot the polar regions. Many indications suggest that the liquid should be composed of a mixture of nitrogen, methane and ethane. Recent observations by Cassini’s Radio Detection and Ranging (RADAR) instrument of Titan’s large sea, called Ligeia Mare, have shown unexplained and ephemeral bright features, possibly due to rising bubbles. Here we report that our numerical model, when combined with experimental data found in the literature, shows that Ligeia Mare’s bed is a favourable place for nitrogen exsolution. This process could produce centimetre-sized and RADAR-detectable bubbles.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: The behaviour of a ternary mixture, N2 + CH4 + C2 H6, at three temperature values relevant to the subsurface environment of Titan’s sea.


  1. 1

    Yung, Y. L., Allen, M. & Pinto, J. P. Photochemistry of the atmosphere of Titan. Comparison between model and observations. Astrophys. J. Suppl. Ser. 55, 465–506 (1984).

    ADS  Article  Google Scholar 

  2. 2

    Krasnopolsky, V. A. A photochemical model of Titan’s atmosphere and ionosphere. Icarus 201, 226–256 (2009).

    ADS  Article  Google Scholar 

  3. 3

    Flasar, F. M. Oceans on Titan? Science 221, 55–57 (1983).

    ADS  Article  Google Scholar 

  4. 4

    Lunine, J. I., Stevenson, D. J. & Yung, Y. L. Ethane ocean on Titan. Science 222, 1229–1230 (1983).

    ADS  Article  Google Scholar 

  5. 5

    Stofan, E. R. et al. The lakes of Titan. Nature 445, 61–64 (2007).

    ADS  Article  Google Scholar 

  6. 6

    Cordier, D., Mousis, O., Lunine, J. I., Lavvas, P. & Vuitton, V. An estimate of the chemical composition of Titan’s lakes. Astrophys. J. Lett. 707, L128–L131 (2009).

    ADS  Article  Google Scholar 

  7. 7

    Tan, S. P., Kargel, J. S. & Marion, G. M. Titan’s atmosphere and surface liquid: new calculation using statistical associating fluid theory. Icarus 222, 53–72 (2013).

    ADS  Article  Google Scholar 

  8. 8

    Brown, R. H. et al. The identification of liquid ethane in Titan’s Ontario Lacus. Nature 454, 607–610 (2008).

    ADS  Article  Google Scholar 

  9. 9

    Zebker, H. et al. Surface of Ligeia Mare, Titan, from Cassini altimeter and radiometer analysis. Geophys. Res. Lett. 41, 308–313 (2014).

    ADS  Article  Google Scholar 

  10. 10

    Hofgartner, J. D. et al. Transient features in a Titan sea. Nat. Geosci. 7, 493–496 (2014).

    ADS  Article  Google Scholar 

  11. 11

    Hofgartner, J. D. et al. Titan’s ‘Magic Islands’: transient features in a hydrocarbon sea. Icarus 271, 338–349 (2016).

    ADS  Article  Google Scholar 

  12. 13

    Lu, B. C. Y., Yu, P. & Poon, D. P. L. Liquid phase inversion. Nature 225, 1128–1129 (1970).

    ADS  Article  Google Scholar 

  13. 12

    Ramírez-Jiménez, E., Justo-García, D. N., García-Sánchez, F. & Stateva, R. P. VLL equilibria and critical end points calculation of nitrogen-containing LNG systems: application of SRK and PC-SAFT equations of state. Ind. Eng. Chem. Res. 51, 9409–9418 (2012).

    Article  Google Scholar 

  14. 14

    Yu, P. A Study of Liquid–Liquid–Vapor Equilibria at Low Temperatures. PhD thesis, Univ. Ottawa (1972).

    Google Scholar 

  15. 15

    Merrill, R. C., Luks, K. D. & Kohn, J. P. Three-phase liquid–liquid–vapor equilibria in the methane + n-butane + nitrogen system. Adv. Cryog. Eng. 29, 949–955 (1984).

    Article  Google Scholar 

  16. 16

    Llave, F. M., Luks, K. D. & Kohn, J. P. Three-phase liquid–liquid–vapor equilibria in the nitrogen + methane + ethane and nitrogen + propane systems. J. Chem. Eng. Data 32, 14–17 (1987).

    Article  Google Scholar 

  17. 17

    Fulchignoni, M. et al. In situ measurements of the physical characteristics of Titan’s environment. Nature 438, 785–791 (2005).

    ADS  Article  Google Scholar 

  18. 18

    Jennings, D. E. et al. Surface temperatures on Titan during northern winter and spring. Astrophys. J. 816, L17 (2016).

    ADS  Article  Google Scholar 

  19. 19

    Le Gall, A. et al. Composition, seasonal change, and bathymetry of Ligeia Mare, Titan, derived from its microwave thermal emission. J. Geophys. Res. (Planets) 121, 233–251 (2016).

    ADS  Article  Google Scholar 

  20. 20

    Tokano, T. & Lorenz, R. D. Sun-stirred Kraken Mare: circulation in Titan’s seas induced by solar heating and methane precipitation. Icarus 270, 67–84 (2016).

    ADS  Article  Google Scholar 

  21. 21

    Tokano, T. Limnological structure of Titan’s hydrocarbon lakes and its astrobiological implication. Astrobiology 9, 147–164 (2009).

    ADS  Article  Google Scholar 

  22. 22

    Mastrogiuseppe, M. et al. The bathymetry of a Titan sea. Geophys. Res. Lett. 41, 1432–1437 (2014).

    ADS  Article  Google Scholar 

  23. 23

    Hayes, A. G. The lakes and seas of Titan. Annu. Rev. Earth Planet. Sci. 44, 57–83 (2016).

    ADS  MathSciNet  Article  Google Scholar 

  24. 24

    Younglove, B. A. & Ely, J. F. Thermophysical properties of fluids. II. Methane, ethane, propane, isobutane, and normal butane. J. Phys. Chem. Ref. Data 16, 577–798 (1987).

    ADS  Article  Google Scholar 

  25. 25

    CRC Handbook of Chemistry and Physics (ed. Lide, D. P. ) (CRC, 1974).

    Google Scholar 

  26. 26

    Gross J. & Sadowski, G. Perturbed-chain SAFT: an equation of state based on a perturbation theory for chain molecules. Ind. Eng. Chem. Res. 40, 1244–1260 (2001).

    Article  Google Scholar 

  27. 27

    Tokano, T., Lorenz, R. D. & Van Hoolst, T. Numerical simulation of tides and oceanic angular momentum of Titan’s hydrocarbon seas. Icarus 242, 188–201 (2014).

    ADS  Article  Google Scholar 

  28. 28

    Clift, R., Grace, J. R. & Weber, M. E. Bubbles, Drops and Particles (Academic, 1978).

    Google Scholar 

  29. 29

    Le Gall, A. et al. Radar-bright channels on Titan. Icarus 207, 948–958 (2010).

    ADS  Article  Google Scholar 

  30. 30

    Cordier, D. et al. Structure of Titan’s evaporites. Icarus 270, 41–56 (2016).

    ADS  Article  Google Scholar 

  31. 31

    Hartwig, J. W. et al. Exploring the depths of Kraken Mare — power, thermal analysis, and ballast control for the Saturn Titan submarine. Cryogenics 74, 31–46 (2016).

    ADS  Article  Google Scholar 

  32. 32

    Lorenz, R. D. et al. Titan submarine: vehicle design and operations concept for the exploration of the hydrocarbon seas of Saturn’s giant moon. In Lunar and Planetary Science Conference, Lunar and Planetary Institute Technical Report 46, 1259 (2015).

    Google Scholar 

  33. 33

    Hollyday, G. et al. Fitting nitrogen solubility lab data for modeling Titan’s lakes and seas. In Lunar and Planetary Science Conference, Lunar and Planetary Institute Technical Report 47, 2292 (2016).

    ADS  Google Scholar 

  34. 34

    Farnsworth, K., McMahon, Z., Laxton, D., Chevrier, V. & Soderblom, J. M. Experimental study of the effects of freezing on liquid hydrocarbons on the surface of Titan. In Lunar and Planetary Science Conference, Lunar and Planetary Institute Technical Report 48, 1974 (2017).

    ADS  Google Scholar 

  35. 35

    Chen, S. & Kreglewski, A. Applications of the augmented van der Waals theory of fluids. I. Pure fluids. Ber. Bunsenges. Phys. Chem. 81, 1048–1052 (1977).

    Article  Google Scholar 

  36. 36

    García-Sánchez, F., Eliosa-Jiménez, G., Silva-Oliver, G. & Vázquez-Román, R. Vapor–liquid equilibria of nitrogen-hydrocarbon systems using the PC-SAFT equation of state. Fluid Phase Equilib. 217, 241–253 (2004).

    Article  Google Scholar 

  37. 37

    Justo-García, D. N., García-Sánchez, F., Díaz-Ramírez, N. L. & Romero-Martínez, A. Calculation of critical points for multicomponent mixtures containing hydrocarbon and nonhydrocarbon components with the PC-SAFT equation of state. Fluid Phase Equilib. 265, 192–204 (2008).

    Article  Google Scholar 

  38. 38

    Justo-García, D. N., García-Sánchez, F., Stateva, R. P. & García-Flores, B. E. Modeling of the multiphase behavior of nitrogen-containing systems at low temperatures with equations of state. J. Chem. Eng. Data 54, 2689–2695 (2009).

    Article  Google Scholar 

Download references

Author information




D.C. wrote the paper and performed PC-SAFT computations, F.G.-S. and D.N.J.-G. made the stability analysis of the N2 + CH4 + C2H6 mixtures, and G.L.-B. provided expertise on the physics of bubbles and effervescence.

Corresponding author

Correspondence to Daniel Cordier.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary Information

Supplementary Tables 1–3 (PDF 84 kb)

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Cordier, D., García-Sánchez, F., Justo-García, D. et al. Bubble streams in Titan’s seas as a product of liquid N2 + CH4 + C2H6 cryogenic mixture. Nat Astron 1, 0102 (2017). https://doi.org/10.1038/s41550-017-0102

Download citation

Further reading