  Titan, Saturn's largest moon, has a dense atmosphere, together with lakes and
seas of liquid hydrocarbons. These liquid bodies, which are in polar regions
and up to several hundred kilometres in diameter, generally have smooth
surfaces despite evidence of near-surface winds. Photochemically generated
organic aerosols form a haze that can settle and potentially interact with the
liquid surface. Here we investigate the floatability of these aerosols on
Titan's seas and their potential to dampen waves. We find that the majority of
aerosols are denser than the liquid hydrocarbons, but that some could have
liquid-repelling properties. From calculation of the capillary forces, we
propose that these 'liquidophobic' aerosols could float and form a persistent
film on Titan's seas. We numerically model the wave damping efficiency of such
a film under the conditions on Titan, demonstrating that even a film one
molecule thick may inhibit formation of waves larger than a few centimetres in
wavelength. We conclude that the presence of a floating film of aerosols
deposited on Titan's lakes and seas could explain the remarkable smoothness of
their surfaces.
