Titan isn’t just Saturn’s largest moon but also the largest one in our Solar System. As it is the only natural satellite with a dense atmosphere, its environment provides a unique recreational opportunity to the health conscious visitor and inhabitant – the ability to actually run across its liquid methane lakes. This has become, by far, one of the most popular activities by both inhabitants and visitors alike.
Titan’s surface temperatures can reach a frigid -179.2˚C and runners need special running suits available for sale or rent. While it is entirely possible to run under your own power, the suit’s built in exoskeleton can augment a person’s running abilities or even take over if need be.
The First Running Rovers
From the first NASA missions to explore Titan’s surface with the Huygens probe in 2005 to the floating probes that landed on the moon’s surface in the 2020’s, NASA soon realized that to better explore the surface, autonomous missions would have to do more – much more. Instead of rolling over terrain or floating over liquid methane lakes, future probes would need to traverse both domains. Probes needed to run!
To figure how to do this, NASA turned to 2013 work done by Italian scientist Francesco Lacquaniti and his research team who worked out the hydrodynamics of running on water in reduced gravity environments. Their work and experiments showed that the model proposed by Glasheen and McMahon in 1996, to explain how basilisk lizards run across water, could be adapted to humans. Lacquaniti and his colleagues were awarded the 2013 Ig Nobel Prize in Physics for their work.
Though the Ig Nobel is generally given to “honor achievements that first make people laugh, and then make them think”, their work, though humorous, was also able to explain why certain types of gait exist. It wasn’t too far off before space agencies around the world were building and sending running robots to traverse Titan’s methane lakes.
Humans Run on Liquid Methane
The work done by Lacquaniti and his team showed that humans could run across water or liquid methane under their own power. As the first colonists inhabited Saturn’s moon, enterprising businesses worked on designing special exosuits modeled after military models that would allow fitness minded individuals to run across methane lakes while protecting them from Titan’s temperatures.
This is possible due to Titan’s reduced gravity, which is 14% that of Earth. On Earth, people are too heavy and don’t have the strength needed to stay above as they stamp their feet on the water’s surface. The reduced weight on Titan means that the impulse a person needs to stay aloft is much lower and well within the realm of the average person’s strength. As a runner stamps their feet using specially designed flippers to increase the surface area of impact, the fluid pushes back up on the person which allows them to run on the surface.
The reduced gravity of Titan affects fluids differently than on Earth. As a person stamps his foot on a liquid’s surface, it splashes to create an air cavity. The person must quickly remove his foot before it is filled or risk being pulled under. In reduced gravity environments, like Titan, the time the air cavity refills is slower and a person can use a much slower stride frequency than on Earth.
Lacquanti and his team used a force unloading pulley system to show that almost anyone could run on water at gravity levels similar to that of our Moon or Titan provided they keep running or jogging in place; something not possible on Earth. Though this seems strenuous, it is not. The lower gravity and the longer time to refill the air cavity makes running easier than on Earth, a result of the higher power and efficiency of the muscles in that environment.
Running on water unaided on Titan is also possible as anyone visiting swimming pools at various recreational centers can see. It is not an uncommon sight to see both kids and adults, wearing specially designed flippers, run and play across the water’s surface. So if you ever wondered what it would be like to run on water, then you should visit Titan for a truly out of the world experience.