Japan’s SLIM Lunar Mission concludes: JAXA reflects on milestones and future analyses

(Image: The Lunar Excursion Vehicle 2 (LEV-2 / SORA-Q) has successfully taken an image of the #SLIM spacecraft on the Moon. LEV-2 is the world’s first robot to conduct fully autonomous exploration on the lunar surface. Credit: https://global.jaxa.jp)

Japan Aerospace Exploration Agency (JAXA) has officially concluded the operations of the Smart Lander for Investigating Moon (SLIM), marking the end of a mission that that achieved significant milestones in lunar exploration, and established Japan as the fifth country to land on the Moon. The agency confirmed the mission's closure at 22:40 JST on August 23, 2024, following unsuccessful attempts to re-establish communication with the spacecraft, which had been lost between May and July.

JAXA said despite facing several obstacles, SLIM achieved notable milestones in lunar exploration. It plans to release a comprehensive report detailing the mission's successes and ongoing analyses.

Mission highlights:

Historic Landing: Launched on September 7, 2023, aboard the H-IIA Launch Vehicle No.47 from Tanegashima Space Center, SLIM made history on January 20, 2024, with Japan's first successful soft landing on the Moon. This achievement positioned Japan as the fifth nation to achieve a lunar landing and set a new standard for precision landing technology.

Mission achievements:

SLIM, launched on September 7, 2023, aboard the H-IIA Launch Vehicle No.47 from Tanegashima Space Center, achieved a significant milestone on January 20, 2024, with Japan's first successful soft landing on the Moon. This achievement made Japan the fifth country to accomplish a lunar landing, setting a new standard in precision landing technology.

Challenges and technical issues:

Despite the above achievements, SLIM faced several hurdles, according to JAXA:

Power generation: An update provided by the agency earlier on January 22 said SLIM, successfully established initial communication with Earth. However, the spacecraft's attitude upon landing did not align as planned, affecting its ability to generate power from its solar cells. Consequently, SLIM was shut down remotely by mission control at 2:57 am JST. The cause of the attitude misalignment is under investigation, with preliminary findings suggesting potential issues with one of the two main engines during descent.

Data recovery and analysis: JAXA had reported that SLIM’s solar cells were oriented to face west, which may allow for power generation if sunlight reaches the lunar surface from that direction. The mission team said it was preparing for potential recovery operations. The mission team continues to analyze the data obtained before the shutdown. This includes investigating the anomalies that affected SLIM’s landing attitude and power generation.

Key successes include:

Here are the updates on the SLIM mission from JAXA

Pinpoint Landing Precision: Pre-shutdown data analysis revealed that SLIM landed approximately 55 meters east of its intended target. Its pinpoint landing capability, with an accuracy of 10 meters or less, fulfilled its primary mission goal of demonstrating landing precision within a 100-meter range. The mission surpassed initial expectations by surviving three lunar nights and conducting high-impact research.

Technical data and research: The spacecraft successfully transmitted technical and image data acquired during its landing descent and operational period. The Multi-Band Camera (MBC) exceeded expectations by performing spectral observations on 10 rocks, while technical data on navigation and descent provided valuable insights for future missions.

Lunar Excursion Vehicles (LEVs): SLIM deployed two small robots, LEV-1 and LEV-2, for lunar surface operations. LEV-1, the world's smallest and lightest direct data transmitter from the Moon, successfully communicated with Earth and executed leaping movements. Both LEV-1 and LEV-2 represent advancements in lunar robotic technology and contributed valuable data to the mission.