ANALYSIS | NASA engineers hope to send a robot snake to explore Saturn’s icy moon Enceladus | CBC Radio

Scientists at NASA’s Jet Propulsion Laboratory have developed a snake-like robot that may one day slither into crevices on Saturn’s icy moon Enceladus.

The robot explorers that have landed on the surfaces of the moon and Mars have been able to roam over rocky terrain using metallic wheels capable of traversing dusty or sandy surfaces. 

But wheels have their limitations, as we discovered with the Mars rovers Spirit and Opportunity. Each was equipped with six wheels, but Opportunity got stuck in a sand dune for a month in 2005, while Spirit got stuck in sand in 2009 and never got out.

Another limitation of wheeled rovers is their inability to deal with very rough terrain. If a hill is too steep, the wheels may slip, and the whole vehicle risks tipping over, so rovers have been sent to fairly safe areas.

The Mars rover operators have also avoided icy terrain because, as anyone who drives in winter conditions knows, getting stuck in snow and ice is far too easy.

One new approach to rover mobility is to abandon wheels altogether and emulate snakes, which are very good at manoeuvring through unusual terrain. The reptile conforms its flexible body to whatever obstacle it encounters and slithers around or over it.

NASA’s EELS project (short for Exobiology Extant Life Surveyor) is a four-metre-long mechanical snake with 10 identical segments, each encased in a shell that forms a helical screw. The rotating screws grip the ground, move it forward and will even be able to self-screw through ice. Meanwhile, the joints between segments enable it to slither from side to side and even lift its head like a snake sniffing the air — in fact its sensor head contains cameras and object-detecting lidar. 

Engineers began building the first EELS prototype in 2019, and they’ll have plenty of time to develop their robot. NASA’s future exploration of Enceladus is only at the concept stage, and even that plan doesn’t imagine a mission leaving before 2038.

They hope this flexibility, along with its skin-like force-sensing actuators to help it feel its way around, will make it more adaptable to extreme terrain. 

A prime target for EELS is Saturn’s moon Enceladus, an ice world with geysers spewing water out of cracks near its south pole, suggesting a subsurface ocean and possible haven for alien life.

Exploring Enceladus’ surface would be similar to traversing a glacier on Earth, where the ice forms deep crevices that would easily swallow a wheeled vehicle.

To that end, the slithery snake has been tested in the snow of a ski resort and on an ice rink. Its sensor head, containing scientific instruments, was lowered into a hole in the Athabasca Glacier in British Columbia. The device was also tested in sand so it could work on the surface of the moon or Mars.

Enceladus is about a billion and a half kilometres from Earth, which means a radio signal takes more than an hour to get there, so the snake robot will be able to navigate entirely on its own. That includes getting itself out of trouble should it fall into a crack or hole.

It will carry an array of sensors that have yet to be selected, but they will likely examine the chemistry of the ice and possibly look for any signs of life. 

Another group at Georgia Tech is taking a lesson from centipedes to create multi-legged robots that can also clamber over rough terrain.

These are the types of robots that could be crawling around of the surfaces of planets and moons in the future.

Humans are proud of inventing the wheel, but nature has provided many other ways to give mobility to animals in a wide variety of environments where wheels cannot go. As we reach out to other worlds with our mechanical pets, taking cues from nature seems a good way to go.

WATCH | An artistic representation of EELS exploring Enceladus.