# How would humans with appropriate equipment travel the surface of Saturn's moon Titan on foot?

Taking into account the physical characteristics of Titan (e.g. surface gravity, atmospheric pressure), what would be the most efficient method of motion for an astronaut to travel the surface of Titan on foot?

Would it be a leaping or hopping motion? Or would it make more sense to walk somehow? I'm unsure how the friction of the ground would accommodate for that.

For the purpose of this thought experiment, lets assume that humanity has the necessary equipment to put an astronaut on Titan and to have protective clothing to enable reasonable safety from environmental hazards on the surface.

For further clarification, the gravity is a comfortable 1.352 m/s2 (0.14 g in comparison with Earth) which equates to .85 Moons. The surface pressure is 146.7 kPa which compares to 1.45 atm (Earth).

In terms of efficiency, it would come down to how much work the human body would have to do to result in an "optimal" speed, by always considering the safety of humans traversing the landscape first and foremost.

Thanks in advance!

• The surface gravity of the Titan nears the Moon, so what we would see is like we could see on the Moon landing wideos of the 70s. – peterh - Reinstate Monica Dec 14 '18 at 13:26
• +1 Great question! I've swapped in "travel" where you had "navigate" because navigation is an excellent but different question than what you are asking. I almost started writing an answer explaining how they could literally navigate their way around. In fact; Why not consider posting a second question asking for various methods they might use to actually navigate their way from point A to point B if (for example) they didn't have a suitably detailed and updated map? – uhoh Dec 14 '18 at 13:45
• Not sure if travelling by foot would be the most efficient way to move on Titan. Human powered flight could be very much faster and fun. – qq jkztd Dec 14 '18 at 13:51
• @peteh the temperature is three times lower, so the density will be about 5 times that of Earth. I don't know about the viscosity, but given that you also have only aboyut 1/7 the weight to give you traction, I think there might be a real risk that you push off the ground and instead of a long hop or glide as you'd get on the Moon, you would come to a stop pretty quickly (like a thrown party balloon) and slowly fall back to the ground. I might be wrong, but I don't think it's obvious either way. – Steve Linton Dec 14 '18 at 14:30
• The flight thing sounds fun, however the lower gravity of Titan will be entirely countered by the weight of all the equipment the human needs for Titan to not kill her. – Mark Adler Dec 14 '18 at 20:43

## 1 Answer

Depending on your environmental suit, it would probably be much like the Apollo astronauts' mode of choice on the moon.

I say "depending on your environmental suit" because the environment at Titan is very different from that on the moon. True, the gravitational acceleration is roughly the same, but a Titan environmental suit wouldn't have to protect against vacuum, and would have to protect against the extreme cold—Huygens measured a surface temperature of 94 K, consistent with radio science measurements at other locations. Insulation against that large a temperature difference would likely be bulky, but could be relatively light compared to the structure needed to contain ~1/3 atmosphere pressure.

Comments have mentioned the high atmospheric density and resulting drag. I calculate a density of ~5.3 kg/m^3, roughly 4 times that at Earth's surface on a 0° C day. At very low speeds, drag is roughly proportional to speed, but at moderate speeds it goes as velocity squared.

Assuming my calculated density, a speed of 1 m/s (~2.24 MPH), and a person with a coefficient of drag times the drag area (suit included) of 1/2 m^2, the drag force would be ~2.6 N, compared to ~0.63 N here at Earth. Although larger, this would be hardly noticeable. Not imperceptible, but not enough to make it an impediment. If that person and their suit comes in at 100 kg the gravity force would be ~135 N, so the drag force is ~1/50 of the gravitational force. Walking normally wouldn't be difficult.

Unless, as was the case with Apollo, a bulky suit makes a normal gait more effort, due to the effort involved in bending the legs. In that case, the "hop" is most comfortable.

• Can you add some kind of link showing how you did your calculations, and also why drag would be more like linear than quadratic low speed? (I still need to know how to calculate a calibration curve for my Phoenix Lander-inspired ping-pong ball anemometer) Thanks! – uhoh Dec 14 '18 at 23:27
• Interesting! Walking with a normal gait would seem to be possible, if not easy taking this into account, but what about higher velocities? If, lets say, the suit allows for it, would it be possible for the astronaut to run? I'm assuming that body control would be impaired heavily for the astronaut due to the more extreme limb movements needed to perform a running motion, but maybe I'm wrong? – Oak Dec 17 '18 at 8:51