“The goal of this mission is to land where you want to land, instead of landing where you can land,” said Hiroyuki Kamata, a professor at Meiji University in Tokyo who helped develop the vision-based navigation system for SLIM, as the Smart Lander for Investigating Moon is known.
The vehicle, which has no people on board, is part of a mission to unravel the origins of the moon through composition analysis of rocks, according to the Japan Aerospace Exploration Agency. It would also facilitate the sampling of lunar permafrost, which could help unveil mysteries about water resources on the moon.
The spacecraft is targeting a landing near a small lunar impact crater called Shioli, near the Sea of Nectar, at 10 a.m. Eastern on Friday. It is aiming to land within 327 feet (100 meters) of its target, far more ambitious than the usual landing zone of several kilometers.
JAXA launched the space vehicle in September, and it entered lunar orbit on Dec. 25. On Monday, JAXA confirmed it would start the landing descent on Friday.
“The biggest challenge is the fact that we only have one shot,” Shinichiro Sakai, the SLIM project manager, said last month. “The final test will be during the last 20 minutes of landing. What we have spent 20 years developing will be tested out in just 20 minutes. We must accomplish this.”
The rover uses a vision-based navigation system to achieve a pinpoint landing. During SLIM’s descent, cameras will take images of the craters on the lunar surface. Using a rapid image-matching algorithm onboard, the images are matched to craters on lunar maps to identify the precise location, and the system will adjust course until SLIM reaches its target landing site.
If the landing succeeds, SLIM will have released two probes equipped to photograph the landing scene, allowing crews on the ground to monitor the spacecraft’s status. The probes would also provide an “independent communication system for direct communication with Earth,” according to JAXA.
Data collected through SLIM will also be used for NASA’s Artemis project, the U.S. effort to place astronauts on the surface of the moon and build a sustainable presence there.
“With the advance of technology and data, gone are the days when merely exploring ‘somewhere on the moon’ was desired,” Sakai said. “There is now a growing demand to pinpoint specific targets like craters and rocks on the lunar surface.”
If the project is successful, the technology will make it easier and more economical for future robotic probes to land precisely at their target sites, said Meiji University’s Kamata. “I imagine that this technology will become useful if we are to build some sort of base on the moon in the future.”
Tomokatsu Morota, an associate professor at the University of Tokyo who specializes in lunar and planetary exploration, said that pinpoint landings will be “a great advantage in the future industrialization of water resources,” one of the goals of the current round of lunar probes. Water is thought to exist as ice in permanently shadowed craters and would be an important resource not just to support a human presence, but also in the potential manufacture of rocket fuel.
Several nations have attempted to land on the lunar surface recently, with mixed results. India successfully landed a spacecraft on the moon in August. But an attempt in April by ispace, a Japanese company, failed, as did one in August by Russia.
NASA is also working to send a fleet of uncrewed spacecraft to the lunar surface ahead of astronaut missions as part of its Artemis program. The first of those, launched earlier this month, was unsuccessful when the spacecraft, developed by Astrobotic, a Pittsburgh-based company, started leaking fuel. While it did travel deep into space, the spacecraft did not have enough fuel to accomplish a soft landing and ended up returning to Earth, where it burned up in the atmosphere.
Intuitive Machines, another U.S. company, is set to launch a spacecraft to the moon next month. If it is successful, it would be the first U.S. space mission in more than 50 years to land softly on the moon, as well as the first commercial vehicle to land on the moon.
Later this year, China is planning to land a craft on the far side of the moon in an effort to bring samples back to Earth. That mission would be China’s second landing on the far side of the moon; in 2019, China became the only country to have successfully landed on the moon’s far side. In 2020, a Chinese spacecraft brought back samples from the lunar surface, another sign of China’s growing space abilities.
