Over two years after Japan’s Smart Lander for Investigating Moon (SLIM) mission deployed a tiny, shape-shifting rover on the Moon, the country’s space agency JAXA has finally revealed previously unreleased details about the first-of-its-kind autonomous robotic lunar exploration.
According to a statement announcing the recently published mission account, the SLIM team deployed the rover on the Moon’s surface, “after which the rover transformed from a tiny sphere into a wheeled robot that took images of the lander and its environment.” A second rover transmitted the data back to Earth, with all steps occurring autonomously.
The team behind the historic mission said their success could pave the way for swarms of small, transformable robots capable of exploring high-scientific value areas that larger spacecraft and robots cannot reach, including caves, tunnels, lava tubes, vents, and deep extraterrestrial craters.
The Benefits of Tiny Robots and Autonomous Shape-Shifting Rovers
In the published study, the JAXA team explains that robotic technologies like SLIM “are expected to drive substantial advancements in planetary exploration and resource prospecting” by performing tasks in extraterrestrial environments that are inaccessible to other platforms, including human astronauts. For example, the team noted that miniature robots offer tremendous weight savings over bulkier platforms, especially when added to missions with “strict payload limitations.”
“Miniature robots have the potential to reduce payloads and to reach cramped spaces such as small vents and craters that are inaccessible to larger, conventional robots,” they explain.
Still, the SLIM team notes that building tiny, shape-shifting rovers capable of exploring a variety of complex environments presents its own set of challenges. The most limiting constraints involve computational power and battery capacity. The team also observed that smaller robotics platforms inherently suffer from “reduced locomotion performance” due to their small size.
Now, when revealing the details of the SLIM mission, the researchers note that advancements in miniaturization and computational performance spurred by the Internet of Things “have catalyzed the emergence of smaller, lighter, and more intelligent rovers at lower costs.”
Introducing the ‘Hopping’ Lev-1 and the ‘Transforming’ Lev-2
To build a tiny, shapeshifting robot capable of exploring the lunar surface autonomously, team leader Daichi Hirano and colleagues designed the Lunar Excursion Vehicle (LEV) system, which comprises LEV-1 and LEV-2. According to the team’s statement, LEV-1 can communicate directly with mission planners back on Earth. For locomotion, the robot moves via what the team termed “a controlled hopping mechanism.”
The second robot, LEV-2, starts out as a compact sphere 8 inches in diameter. However, once on the Moon, the mission controllers said that the tiny robot can transform into a “two-wheeled rover with cameras and a tail stabilizer.”
“Here, we introduce a two-wheeled centimeter-scale rover, designated Lunar Excursion Vehicle 2 (LEV-2), also known as SORA-Q (named after the Japanese words for space and sphere), which transforms into a wheeled configuration from a compact spherical form, enabling efficient traversal of soft lunar terrains,” they write.
Transformers Make Autonomous Robotic Exploration History
According to the new mission details, the SLIM lander deployed LEV-2 “immediately before its landing on the lunar surface.” In the mission details, the team explained that upon deployment, the rover autonomously extended its wheels, tail stabilizer, and cameras, “thereby enhancing its mobility and stability on soft lunar terrain.”
After deployment, LEV-2 navigated the lunar surface in the immediate area around the lander. According to the published study, “the palm-sized rover accomplished autonomous lunar exploration by navigating around the SLIM lander, capturing images of both the SLIM lander and its environment.” Critically, the rover’s exploration was autonomous and “without reliance on ground-based teleoperation,” marking a historic first in lunar exploration.
After finishing its exploration, the tiny robot transmitted images of its adventures to LEV-1. The hopping rover then transmitted the data to Earth. The team notes that all these steps were also accomplished autonomously.
The team notes that the LEV-2 shape-shifting rover operated for “more than 100 minutes: before losing communication with LEV-1. Although determining the exact cause may require direct examination of the two robots, Hirano’s team suspects that issues caused by LEV-1’s hopping motions or battery depletion “may have contributed to connectivity issues.”
Exploring High-Risk, Scientifically Valuable Environments
When discussing the implication of an autonomous, shape-shifting rover successfully navigating the lunar surface and completing its mission directives, the team concedes that the capabilities of a single, small rover like LEV-2 “are inherently limited.” However, they also note that their mission success highlights the potential of this category of robotic platform “as independent explorers, capable of accessing environments beyond the reach of a primary large spacecraft.”
“Swarm-controlled small robots are poised to be deployed in high-risk yet scientifically valuable environments, such as vents, caves, and steep slope craters, that are inaccessible to larger, conventional rovers,” the researchers conclude. “This approach promises to enhance both the efficiency and safety of future planetary surface exploration.”
The study “From ball to rover: Transformable palm-sized rover SORA-Q for autonomous lunar exploration” was published in Science Robotics.
Christopher Plain is a Science Fiction and Fantasy novelist and Head Science Writer at The Debrief. Follow and connect with him on X, learn about his books at plainfiction.com, or email him directly at christopher@thedebrief.org.