Voyage across Ligeia Mare: Mechanics of sailing on the hydrocarbon seas of Saturn's Moon, Titan

Like sailing ships, drifting buoys and icebergs on the seas of Earth, the motion of a capsule floating on the cold methane/ethane seas of Saturn's moon Titan results from the balance of aerodynamic and hydrodynamic forces above and below the 'waterline'. This balance is evaluated in the context of a NASA proposal to send such a capsule to perform oceanographic and other measurements on the similar to 400 km wide Ligeia Mare in 2023. Taking liquid and air density into account (the sea:air density ratio on Titan is similar to 100, compared with similar to 800 on Earth) in the drag balance, it is expected that the vehicle will drift at a fraction f of the near-surface windspeed with f similar to 0.08-0.18. Consideration of wave effects suggests a correction of the form f' similar to f(1 +0.7U(10)(4)). Winds of about 0.3 m/s are expected in this season (late Northern summer), and drift trajectories using two different global circulation models are computed. It is expected that the vehicle would encounter the coastline after drifting similar to 150 km over 2-10 Titan days (similar to 32-150 Earth days.) (C) 2015 Elsevier Ltd. All rights reserved.