Japan’s Moon landing was the most precise ever

Japan has become the fifth country to soft-land a spacecraft on the Moon, using precision technology that allowed it to touch down closer to its target landing site than any mission has before. However, the spacecraft might have survived on the lunar surface for just a few hours, owing to a power failure.

Telemetry data indicated that the Smart Lander for Investigating Moon (SLIM) successfully landed in its designated area near Shioli crater, south of the lunar equator, early Saturday morning. This achievement follows its launch from the Tanegashima Space Centre, located off the south coast of mainland Japan, four months prior.

Hitoshi Kuninaka, the vice president of the Japan Aerospace Exploration Agency (JAXA), shared the news during a press conference after the landing. He reported that SLIM had reached the Moon’s surface, maintained communication with the ground station, and executed commands from Earth accurately. However, Kuninaka noted a concern about the solar cells, which were currently inactive, leading the spacecraft to rely solely on its battery. He mentioned that the battery had limited remaining life, lasting only a few more hours. Despite this, JAXA expressed optimism and committed to monitoring the lander, as there was a possibility that the solar panels could resume functioning.

This successful landing occurred approximately two weeks after the launch of a US commercial spacecraft intended for the Moon. Unfortunately, a propellant issue will prevent the latter from landing as originally planned. Furthermore, it marks almost a year since a Japanese commercial lander faced a failure and crashed on the Moon. Lunar landings pose significant challenges, and successful attempts by commercial companies remain elusive.

The accomplishment is a big win for Asia, as in the past decade, only China, India, and Japan have successfully deployed spacecraft on the Moon, with India achieving a successful landing last August.

It is highly probable that SLIM successfully accomplished its primary objective – landing on the Moon with an unprecedented precision of 100 meters, a substantial improvement from the previous ranges of a few to dozens of kilometers. The key technology employed by SLIM was vision-based navigation, allowing it to capture images of the lunar surface during its flight and rapidly determine its location by matching these images with onboard maps.

The manner in which the car-sized, 200-kilogram spacecraft touched down in its planned two-step sequence remains uncertain. Unlike previous landers that simultaneously landed on four legs in a relatively flat area, SLIM was designed to first touch a 15-degree slope outside Shioli crater with one leg at the back before tipping forward and stabilizing on its four front legs.

Some observers speculate that SLIM might have rolled during touchdown, preventing its solar cells from facing the Sun. Insufficient data are currently available to determine the probe’s posture or orientation. However, if sunlight reaches the solar cells, there is a possibility of SLIM resuming functionality. Two small robots were intended to eject from SLIM before touchdown to capture images of the lander for transmission back to Earth. However, it remains unclear whether these robots were successfully deployed.

In the event that SLIM reactivates, scientists plan to utilize a specialized camera, the sole scientific instrument onboard, to search for a mineral called olivine in the Moon’s mantle. Detecting olivine’s components and comparing them with Earth’s counterparts could provide new evidence supporting the theory that the Moon was once part of Earth. Additionally, the camera would contribute to confirming the origin of Apollo 16 Moon samples. Positioned approximately 250 kilometers east of Apollo 16’s 1972 landing site and west of the ancient lunar sea Mare Nectaris, SLIM’s findings could offer valuable insights into impact dynamics and the chemistry of the ancient lunar sea, showcasing the productivity and scientific significance of smaller missions.Top of Form

Sakai and his team envisioned that SLIM’s precise landing technology would provide Japan with an advantage in the US-led Artemis Program, which aims to reintroduce humans to the Moon by 2026. Sakai expressed the potential application of this technology in various missions, emphasizing its role as a Japanese contribution to international cooperation.

While SLIM’s success puts Asia in the spotlight in the emerging lunar exploration race, it could also heighten competition among spacefaring nations in the region. With both India and Japan achieving technologies for soft landings on the Moon, their collaborative Lunar Polar Exploration Mission may pose a significant challenge to China’s Chang’e-7 mission, set to land in the lunar south pole region in 2026 with a focus on ice exploration.

The Moon is witnessing an increase in exploration activities. SLIM marked the second Moon landing attempt in the current year, following the unfortunate outcome of the US Peregrine spacecraft. In the coming month, the US company Intuitive Machines is set to continue its endeavour to become the first commercial entity to land a spacecraft on the Moon. Additionally, China plans to launch its Chang’e-6 mission later this year, aiming to collect samples from the far side of the Moon.