Adorable, ball-shaped robot ‘crawled’ across the moon during Japan’s historic first lunar landing
When the Japanese Smart Lander for Investigating the Moon (SLIM) spacecraft, nicknamed the “Moon Sniper”, Face-planted on the surface of the Moon in 2024An experimental rover told Earth scientists what had happened. Moving autonomously through the moon dust, the shape-shifting spherical robot – not unlike Star Wars’ BB-8 droid – took photos of the inverted lander and transmitted them to Earth, completing its mission while SLIM slowly froze.
“The results highlight the potential of such platforms … as independent explorers, capable of reaching environments beyond the reach of primary large spacecraft,” the research team, which was led by Japan Aerospace Exploration Agency scientist Daichi Hirano, wrote in the paper. Rover designed.
The ball-shaped rover, called the palm-sized Lunar Excursion Vehicle 2 (LEV-2), was one of the payloads on SLIM, which created a soft moon touch On January 19, 2024. This achievement made Japan the fifth country to reach the Moon, but trouble arose when SLIM could not generate electricity from its solar panels.
While SLIM was running on reserve battery power, it deployed LEV-2 – a shapeless, spherical robot that could change shape using two wheels inside a ball, depending on the terrain it encountered – as well as LEV-1, a rover that “hop” across the terrain. After deployment, LEV-2 operated for about 100 minutes and transmitted information through LEV-1, before losing communications.
Despite its short life, LEV-2 proved critical to troubleshooting the mission, as it revealed that the SLIM lander had fallen upside down on the surface, the authors write in the new paper.
“The palm-sized rover completed autonomous lunar exploration by navigating around the SLIM lander, capturing images of both the SLIM lander and its environment, and transmitting selected images to the lunar surface via wireless communications,” the team reported.
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Despite the obstacles, SLIM managed to capture enough solar energy to survive three cool lunar nights (each lunar night lasting about 2 weeks, when the Earth-facing side of the Moon is at an angle away from the Sun). Released to controllers in February, March and April before SLIM was silenced and ceased to exist Declared dead in late August. Meanwhile, LEV-2 fulfilled its primary mission objective of acquiring and transmitting images to the spacecraft, “thereby providing important supplemental data for a comprehensive assessment of the lunar landing outcome,” the team wrote.
A photo showing LEV-2 in ball form (left) and expanding to fly past the Moon with its metal wheels (right). A model of the SLIM lander sits in the background, upper right.
(Image credit: D. Hirano)
The authors said LEV-2 also demonstrated technologies that will be important for future missions to the Moon and Mars. For example, its morphable mobility technology successfully moved the rover around the surface, and the robot showed “autonomous navigation and control systems” while processing images to traverse the lunar surface.
lessons learned
The team also extracted some “lessons learned” from the mission to improve the adapted rover design for future excursions.
First, their goal will be to record the vehicle’s position more frequently. LEV-2 sent telemetry every 32 seconds, which “limited direct observation of position changes and actions.”
Second,There is a need to increase communication. communication betweenLEV-2 and LEV-1 limited the available telemetry needed to reconstruct the state. [spacecraft-shape] changes during surface operations,” the team noted.
Ultimately, the rover software needs to be improved. Controllers may observe the LEV-1 recovering from problems related to wheel-rotation lock and its attitude, due to its fault detection and recovery systems. But the software had a limited number of states and transitions pre-loaded, which could present a problem on longer missions, especially if the unexpected happens.
While the small vehicle had limitations, investigators noted that LEV-2 met its goals and that the technology had room for improvement.
“In the long term, this approach could enable more flexible, robust and cost-effective planetary exploration missions,” he said. “The lessons learned from this mission provide practical guidance for the design and operation of next generation distributed space robotic systems.”
