A pair of tiny robots made giant leaps showing off a new range of miniaturized technologies in a Japan Aerospace Exploration Agency landing on the moon. 

Among their accomplishments was documenting the historic landing of JAXA's Smart Lander for Investigating Moon (SLIM) probe, making Japan only the fifth country to land an unmanned spacecraft on the moon. 

The photo captured by a tiny machine about 8 centimeters in diameter shows that SLIM landed on the surface on Jan. 20, but upside down. 

“The moment I saw the picture, I almost couldn't remain standing,” said Shinichiro Sakai, SLIM’s project manager, recalling what he felt at the sight of SLIM’s main engine loo0king upward.

CRUCIAL EVIDENCE

The two small robots were released onto the moon when SLIM was nearing a point 5 meters above the surface.

LEV-2, which weighs 250 grams and is about the size of a baseball, transformed following its landing to start its mission. Its center portion opened, with more than one image being snapped.

The data was delivered to its robotic partner, LEV-1, which received the images by radio, then transmitted them 380,000 kilometers back to Earth.

The photos provided definitive proof that SLIM had actually landed on the lunar surface. 

Daichi Hirano, a chief research and development engineer at JAXA, expressed delight during a news conference in late January.

“I was relieved that SLIM had successfully been photographed to meet our expectations,” he said.

However, data was in part lost, much to the technician’s regret, due to communication problems.

“Even more clear images should have been delivered,” Hirano lamented.

MANY FIRST-TIME FEATS

LEV-1 was not only responsible for communications but also equipped with a specialized means of mobility. 

Its 2-kilogram body, about the size of a basketball, was fitted with a spring system that allowed the robot to hop off the moon's surface via motor-compressed spring power.

Reports from the moon reveal LEV-1 made six leaps, meaning it jumped several meters across the surface like a frog to make it the first robot to traverse Earth's satellite or any celestial body with gravity with the assistance of a hopping device.

The technology tested is expected to offer a new transit method for probes to hurdle large rocks at some point.

Various other accomplishments were likewise achieved by the robotic explorers in the latest operation.

LEV-2 turned out to be the smallest and lightest machine that has worked on the moon.

On top of that, LEV-1 and LEV-2 were engaged in the simultaneous exploration of the moon together and communicated with each other.

It was alike the first time for fully autonomous vehicles to be involved in explorations with no assistance from Earth.

Both LEV-1 and LEV-2 have already exhausted their batteries to bring an end to their missions. Data sent from the probes are currently being analyzed.

“We will be looking at their operating records to take advantage of their findings for future space exploration initiatives,” said Hirano.

INSPIRED BY SEA TURTLE

The compact LEV-2 robot, aka "Sora-Q," was developed by Kimitaka Watanabe, an engineering professor at Doshisha University, who said with a grin that he was “impressed” by his brainchild, which took the image of the SLIM probe. 

Watanabe, who had been a staff member of leading toymaker Tomy Co. up until 2020, made full use of toy transformation technologies and other skills for the space program.

This enabled him to realize a simple design full of innovations, leading to LEV-2’s success.

When Watanabe began cooperating with JAXA for research in fiscal 2016, the possibility was suggested that tiny robotic explorers might be stuck or buried in sand.

The moon’s surface is covered by a layer of sand known as regolith. There appear to be steep slopes on the lunar surface marked by weaker gravity than found on Earth.

Providing a clue to the solution was the way newly hatched sea turtles climb sloped sand beaches.

“They lie flat and crawl,” explained Watanabe. “I considered how to replicate this methodology with wheels.”

The idea he hit upon was that the center of gravity of spinning wheels should be shifted slightly from the center portion. With this in mind, LEV-2 was made to move forward awkwardly but stably even on 30-degree slopes.

LEV-2 was streamlined so its body eventually measured only 8 cm in diameter. The compact size meant LEV-2 could be mounted on SLIM.

Watanabe monitored SLIM’s landing at JAXA’s mission control center.

Its arrival on the moon was not enough for him to relax, given that LEV-2 was still tasked with recording and sending photos completely autonomously via LEV-1. There was no knowing if any unexpected developments might occur during that process.

Watanabe confessed he was finally relieved to hear that an “astonishing thing had been captured.”

“I am nearly 100-percent satisfied with the outcome even though the results of the analysis of the machine’s operational logs have yet to be released,” he said proudly.

(This article was written by Tetsuya Ishikura and Tomoyuki Suzuki.)