The Japan Aerospace Exploration Agency (JAXA) has ended its Smart Lander for Investigating Moon (SLIM) mission after losing contact with the spacecraft in late April. The lunar lander surpassed performance expectations, successfully performing spectral observations in ten wavelength bands on ten rocks and surviving six weeks (or three lunar nights) on the surface where temperatures can drop to -170˚ Celsius.
In an August 26, 2024, statement, JAXA said they had unsuccessfully attempted to re-establish contact with SLIM during operational periods across May – July before deciding to send a signal to shut down the lander.
“We judged that there was no prospect of restoring communication with SLIM, and at around 22:40 (1340 GMT) on August 23, we sent a command to stop the SLIM activity,” JAXA posted on its social media platforms.
Among other things, the spectral observations confirmed the existence of a mineral called olivine, which JAXA scientists say could provide clues as to the origin of the Moon.
SLIM was a technology demonstrator, and the agency says the experience gained in precision landing and other technologies will be inherited by future missions.
The H-IIA Launch Vehicle No.47 took SLIM into orbit on September 7, 2023, from the Tanegashima Space Centre and achieved Japan’s first Moon soft landing on January 20, 2024. The landing precision was evaluated with a position error of approximately 10 metres from the target point, confirming the world’s first successful pinpoint landing.
The January landing on the Moon made headlines. Aside from Japan becoming just the fifth country to put a spacecraft down on the Moon, the lunar lander landed with its solar panels facing the wrong way. However, it powered back up and conducted experiments before succumbing to the cold. JAXA re-established contact twice after that, receiving data and images back both times. The last contact was made on April 28.
The 200-kilogram dry mass lander carried two probes, one with a transmitter and a mini-rover that moved like a turtle around the lunar surface, sending images back to Earth. It had two specific missions: demonstrating high-precision landing technology compared to the conventional lunar landing accuracy of several kilometres to tens of kilometres and demonstrating a lightweight lunar and planetary probe system to allow more frequent lunar and planetary exploration missions. The scientific experiments were the cream on the cake.
Initially, JAXA engineers were shooting for an accuracy figure of 100 metres. They managed to land it within 55 metres of the target site.
SLIM was under development for 20 years before finally launching. During that time, JAXA and numerous universities and institutions were actively engaged in researching and developing various technologies to achieve the mission.
“SLIM continued to transmit information on its status and the surrounding environment for a much longer period than expected, “JAXA’s social media post added. “At the time of launch, no one imagined that the operation would continue this long.”
The space agency says it will compile and release a detailed summary of SLIM’s achievements in due course.
