A snake robot could explore extreme terrains on icy moons of Saturn like Enceladus. According to members of NASA‘s Jet Propulsion Laboratory (JPL) team, this new type of explorer appears to be highly advantageous. Saturn’s moon Enceladus is famous for spewing water through its icy crust and is one of the best places to search for life in the Solar System.
To navigate the moon’s surface, the Exobiology Extant Life Surveyor (EELS) is designed to use multiple rotating segments connected in series, allowing it to twist and bend like a snake through otherwise impassable terrain for rovers and landers.
Reasons for a snake robot
The EELS team is employing a “startup” mindset to rapidly advance the project, which is in its early stages and has not yet been approved for funded missions. “Build fast, test often, learn, adjust, repeat” officials said in a post (ref.) on the JPL website on Monday, May 8th.
The rotating segments of EELS are wrapped in a thread-like structure, which it uses to push against various surfaces. The snake-like capability and the ability to move the segments independently enable the robot to maneuver in tight spaces, climb or descend into areas that conventional equipment would not be able to reach.
“It has the ability to go places where other robots can’t go” said EELS project manager Matthew Robinson. “While some robots are better on a particular type of terrain or another, the idea for EELS is total versatility”. EELS has undergone several modifications over time, with the research team testing which materials and design specifications work best. The current version consists of 10 rotating segments, weighs 100 kilograms, and is 4 meters long. The sections are actuated by 20-centimeter plastic screws for testing on sandy terrains and metal screws to gain traction on ice.
Tests conducted
So far, the team has tested EELS in various challenging environments. The robot’s head is equipped with cameras to help EELS analyze and traverse different environments, creating 3D maps of its surroundings. To verify this, EELS researchers lowered a prototype of the snake robot’s head into an icy crevice similar to what it might encounter on Enceladus.
NASA is relying on EELS to make its way through Enceladus’ surface ice. In addition to being highly maneuverable, it will also need to be fully autonomous. On average, a radio signal takes about 1.5 hours to travel the distance between Saturn and Earth.
This delay means EELS will have to interpret the surrounding environment, autonomously assess potential hazards, choose possible paths, differentiate and select data collection targets, and even recover from unexpected events. The team began monthly hardware and software tests in 2022, primarily to enhance its independence capabilities. “The robot will have to understand what the path is and try to follow it” said Rohan Thakker, automation lead.
Enceladus and other future applications
Enceladus is an icy moon orbiting Saturn. Its surface is covered in long fissures known as “tiger stripes” which spew water jets from oceans beneath kilometers of ice. These geysers are expelled with such force that one of Saturn’s rings is composed of the ejected ice particles. Measurements have detected large amounts of organic material within these plumes. For this reason, NASA has identified Enceladus as one of the primary contenders among planetary bodies in our Solar System capable of hosting life.
But EELS could have much closer-to-home applications. The JPL team foresees the robot’s adaptability being useful to researchers on Earth studying environments such as glaciers and caves. It could also crawl to explore underground lava tubes and other geological features on closer worlds like the Moon and Mars.
“So far, our goal has been to refine the autonomous mobility capability. Only later will we look at what scientific instruments we can integrate with EELS” said Robinson. It is unclear when EELS or a similar technology could take flight. The latest planetary research survey suggests a future combined orbiter and lander/robot mission to Enceladus.