Japan's SLIM Moon Lander Crash Investigated by Experimental Ball-Shaped Rover
A new study published in Science Robotics details how SORA-Q (LEV-2), a palm-sized spherical rover developed by JAXA, Sony, Doshisha University, and toy company Takara-TOMY, autonomously explored the lunar surface for roughly 100 minutes following Japan's SLIM landing in January 2024. The baseball-sized robot transformed from a sphere into a two-wheeled rover, captured 12 high-resolution images of the upside-down SLIM lander and its surroundings, and relayed data to Earth via a companion rover, LEV-1. The mission demonstrated that extremely compact robotic platforms can conduct autonomous surface operations and could serve as flexible, low-cost sidekicks for future planetary exploration.
SORA-Q, officially designated Lunar Excursion Vehicle 2 (LEV-2), landed on the Moon on January 19, 2024, aboard JAXA's Smart Lander for Investigating Moon (SLIM) mission. Measuring just 80 millimeters (about 3 inches) in diameter and weighing approximately 250 grams, the rover transformed from a compact sphere into a two-wheeled vehicle using a rotating internal shaft and off-center wheel rotation technology borrowed from commercial toy design — a collaboration with Takara-TOMY, co-owner of the Transformers brand. As shown in mission diagrams, SORA-Q was deployed before SLIM's touchdown, then expanded and navigated autonomously around the lander, which had face-planted due to a thruster failure and landed with its solar arrays facing the wrong direction. The rover captured 12 high-resolution images and transmitted them to Earth through LEV-1, a companion hopping robot, without relying on direct ground teleoperation. SORA-Q operated for approximately 100–108 minutes before losing communication with LEV-1, likely due to LEV-1's battery depletion or damage from its hopping motion. Some data was lost during transmission. The study concludes that small rovers like SORA-Q could complement larger rovers by accessing cramped environments such as craters and vents, and that distributed robotic systems combining large and small platforms could enable more flexible and cost-effective space missions.
Limitations & open questions
The study's own limitations include data loss during transmission and the premature end of communications before SORA-Q's expected operational lifetime, leaving some uncertainty about the rover's final status and the completeness of the dataset. The paper does not fully resolve whether LEV-1's failure was due to battery depletion or physical damage from hopping, and the long-term implications of the toy-derived transformation mechanism for reliability in harsher or longer missions remain untested.
What different sources said
- Phys.orgCenter
How a shape-shifting tiny rover inspired by Japanese toys autonomously explored the moon
- Live ScienceCenter
See the 'crawling,' ball-shaped robot that rolled around the moon during Japan's historic first landing
- Scientific AmericanCenter
Meet LEV-2, a baseball-sized and absurdly cute moon robot
- GizmodoCenter
Two Years Later, We’re Finally Learning How a Transformers-Inspired Rover Fared on the Moon
- Space.comCenter
How Japanese scientists sent a real-life Transformer to the moon
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