NASA's EELS: A Snake-like Robot to explore the oceans of Saturn's moon, Enceladus

"NASA's Snake-like Robot EELS Designed to Explore the Subsurface Oceans of Saturn's Moon Enceladus"

Image Credit: Popular Mechanics

According to NASA, the Jet Propulsion Laboratory (JPL) is currently experimenting with a serpent-like robot that has the potential to explore the subterranean oceans of Enceladus, one of Saturn's moons, by penetrating through surface vents.

JPL is developing the Exobiology Extant Life Surveyor (EELS) robot to independently chart, cross and investigate locations that would normally be impossible to reach on Earth, the Moon, and other planets in the solar system.

The JPL initiated the initial development of the EELS prototype in 2019 and has been consistently modifying it ever since. As of 2022, they have been conducting monthly field tests while simultaneously enhancing both the hardware and software components of the robot.

The current version of the robot, named EELS 1.0, has a length of 4 meters and weighs approximately 100 kilograms. It is composed of ten identical segments that use screw threads to rotate for traction, grip, and propulsion.

The robot has undergone testing in various conditions, including sandy, snowy, and icy environments. These tests have been conducted in JPL's Mars Yard, which is designed to mimic the terrain of Mars and is located in a ski resort.

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The robot's ability to operate autonomously is critical due to the significant communication delay between Earth and other celestial bodies in deep space. For instance, a radio signal sent to Saturn would take roughly 83 minutes to travel in one direction.

Because of the communication delay between Earth and other celestial bodies, EELS will need to rely on autonomous sensing and risk calculation to navigate and collect data using its scientific instruments. The specific science instruments to be included in EELS have not yet been determined.

Rohan Thakker, the autonomy lead on the project, explained in a press statement that EELS faces a significant challenge similar to an autonomous car that must navigate without any stop signs, traffic signals, or roads. He likened the robot's task to identifying the path ahead and attempting to follow it.

To achieve this, EELS employs eight stereo cameras and lidar to generate a 3D map of its environment, which is then used by navigation algorithms to determine the safest path for the robot. The engineering team is working on developing a "library" of movements for the robot that can be used to navigate different types of terrain. This library includes movements such as sidewinding and "banana," a technique in which the robot curls in on itself.

JPL expects the final version of the robot to have 48 actuators or miniature motors, which will provide it with a great deal of flexibility. However, this will also increase the complexity for both the hardware and software teams.

Thakker likens these 48 actuators to "48 steering wheels." Many of these actuators will have integrated force-torque sensing, which works similar to skin, allowing EELS to "sense" the amount of force it exerts on the terrain.