The abstract to the recent paper Never-EVER Land - A Titan Flyer Concept is shown below.

I've asked about the need for the aircraft to remain in flight continuously and land only at the end of it's primary mission in the question Why Never-EVER Land? and several good answers explain some reasons why a surface landing would be difficult. It's worth reading those answers so I won't review them here, but since the flyer is a fixed-wing design and not a multi-copter, it's not hard to guess.

But the last line in the abstract also mentions a "water" landing. Of course the liquid in Titan's cryogenic lakes is not water, but instead probably light hydrocarbons and other things that are gases on Earth.

I'm wondering if the liquid is low viscosity and would be potentially amenable to regular liquid landings and subsequent takeoffs, or if it's sticky and tar-like.


The Saturnian moon Titan is potentially one of the most vibrant bodies in the Solar System, possessing a thick atmosphere and surface lakes of hydrocarbons and other organic chemicals, which makes it one of the biggest targets in space exploration. Traditional options to explore the moon include telescopes, orbiters, landers, and rovers, but there exists a research gap between the detail of the orbiters and land based craft. To close this gap, Oklahoma State University, proposes the Never-EVER Land, a conceptual aircraft design that would fly a long endurance mission on Titan to analyze its atmosphere and geography. The flyer’s push configuration, electronic motor-driven propellor and scientific package is powered by a Segmented Thermoelectric Modular Radioisotope Thermoelectric Generator (STEM-RTG). The polyhedral wing uses a high lift-to-drag airfoil to maximize aerodynamic efficiency. In order to fit Never-EVER Land into a launch vehicle, the flyer has a twin-boom tail configuration that allows the empennage to slide over the fuselage, and folding wings. Material choices are tentatively carbon fiber, Nomex honeycomb, and Titanium-based, with a new self-healing skin for resilience and strips of aluminum or copper to conduct heat from the STEM-RTG to the rest of the flyer. The front of the fuselage possesses an integrated communications and control unit, onboard autopilot, and ample space that can be used for instrumentation tailored for specific missions. Ventilation ports and externally mounted sensors can provide access to the atmosphere and windows can be built to provide line of sight. Given ideal conditions, Never-EVER Land is projected to fly for 2 to 3 years before gliding into a lake or flat surface on the surface of Titan. (Emphasis added)


According to NASA's article "Rainbows on Titan":

The density of liquid methane is only about half the density of water. This is something, say, a boat builder on Titan would need to take into account. Boats float when they're less dense than the liquid beneath them. A Titan-boat would need to be extra lightweight to float in a liquid methane sea. ...

Liquid methane also has low viscosity (or "gooiness") and low surface tension.

The table in that article shows that liquid methane at 0.184 cP has only about 1/8 the viscosity of water, 1.54 cP.

The composition of the main liquid bodies on Titan is likely not pure liquid methane, cf. An Estimate of the Chemical Composition of Titan's Lakes -- the other main constituents such as liquid nitrogen, liquid ethane, etc. are also extremely low in viscosity, so it seems likely that the viscosity of any blends will be low.

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    $\begingroup$ Wow, totally different than I'd imagined! I realize now that my use of "tar-like" probably comes from the black appearance of the lakes in many images, but those are radar images and so have nothing to do with the visual appearance. $\endgroup$ – uhoh Mar 22 '18 at 23:41
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    $\begingroup$ The low viscosity means it’s harder to make an effective propellor: it’s going to be hard to take off. The low density means that displacement drag is less, so deceleration on landing will be smoother. $\endgroup$ – Bob Jacobsen Mar 23 '18 at 0:24
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    $\begingroup$ Low density and low surface tension, so we should probably go straight to submarines. $\endgroup$ – Russell Borogove Mar 23 '18 at 1:03

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