9:00 AM - 9:20 AM
[PPS09-01] Smart Lander for Investigating Moon (SLIM): Results from the Moon Landing
★Invited Papers
Keywords:lunar exploration, moon landing, precision landing, pinpoint landing, SLIM
SLIM(Smart Lander for Investigating Moon) is a JAXA project aiming to contribute to future lunar and planetary exploration by achieving the following two objectives: 1) Demonstration of high-precision landing technology on the moon, and 2) Realization of a lightweight lunar and planetary probe system to allow more frequent lunar and planetary exploration missions. Target landing accuracy is 100m, which is significant improvement compared to kilometers to 10+ kilometers of conventional lunar landers.
SLIM was launched with X-Ray Imaging and Spectroscopy Mission(XRISM) with H-2A rocket on 7th, September,2023. After the successful launch, SLIM was operated in Earth-orbiting phase, Luna transfer phase, and deep space cruising phase, and inserted into luna orbit on 25th, December 2023. Several orbital maneuver operations decreased the orbit altitude, and reached about 600km x 15km orbit. Finally, descent and landing sequence was started on 20th, January 2024 0:00 from the point with 15km altitude.
During the powered descent and vertical descent phase, SLIM was in healthy status. Vision-based navigation with navigation camera was conducted twice on the spacecraft for seven areas, and all completed successfully. Another computationally intensive algorithms were performed on ground, and all results were consistent. It means that all 14 vision-based navigation results should be accurate. Guidance & control appropriately corrected the landing orbit toward the target.
At around 50m altitude, obstacle detection was performed twice, both times completed successfully. After the obstacle detection, SLIM was designed to start obstacle avoidance to the target believed to be relatively safe. It means that, pinpoint landing accuracy should be evaluated before obstacle avoidance.
Two images captured by navigation camera for obstacle detection were compared with the image captured by Chandrayaan-2, to estimate the distance from the target landing point to the SLIM position when each image was captured. The estimated distance was 3.4m for the first image, and 10.2m for the second image. Since the latter one is thought to be already drifted eastwards due to the abnormal event described below, we estimate the actual pinpoint landing accuracy is likely to have been about 3-4m.
However, around the timing of obstacle detection, an abnormality occurred in the propulsion system, and it resulted the loss of most of the thrust generated by one of two main engines. Since the dual main engine design allowed a certain level of redundancy, and the onboard navigation guidance control system detected an abnormality, spacecraft drifted eastwards and descend slowly. During this process, LEV-1 and LEV-2 (SORA-Q) were separate at an altitude of about 5m. Finally, spacecraft landed with slower rate of descent than the specified range. However, landing conditions such as the lateral velocity and attitude exceeded the specified range and produced a large attitude fluctuation after landing that resulted in a settled attitude different to expected.
Details in the descent and landing operation will be reported in the presentation, with the post landing operations and these results.
SLIM was launched with X-Ray Imaging and Spectroscopy Mission(XRISM) with H-2A rocket on 7th, September,2023. After the successful launch, SLIM was operated in Earth-orbiting phase, Luna transfer phase, and deep space cruising phase, and inserted into luna orbit on 25th, December 2023. Several orbital maneuver operations decreased the orbit altitude, and reached about 600km x 15km orbit. Finally, descent and landing sequence was started on 20th, January 2024 0:00 from the point with 15km altitude.
During the powered descent and vertical descent phase, SLIM was in healthy status. Vision-based navigation with navigation camera was conducted twice on the spacecraft for seven areas, and all completed successfully. Another computationally intensive algorithms were performed on ground, and all results were consistent. It means that all 14 vision-based navigation results should be accurate. Guidance & control appropriately corrected the landing orbit toward the target.
At around 50m altitude, obstacle detection was performed twice, both times completed successfully. After the obstacle detection, SLIM was designed to start obstacle avoidance to the target believed to be relatively safe. It means that, pinpoint landing accuracy should be evaluated before obstacle avoidance.
Two images captured by navigation camera for obstacle detection were compared with the image captured by Chandrayaan-2, to estimate the distance from the target landing point to the SLIM position when each image was captured. The estimated distance was 3.4m for the first image, and 10.2m for the second image. Since the latter one is thought to be already drifted eastwards due to the abnormal event described below, we estimate the actual pinpoint landing accuracy is likely to have been about 3-4m.
However, around the timing of obstacle detection, an abnormality occurred in the propulsion system, and it resulted the loss of most of the thrust generated by one of two main engines. Since the dual main engine design allowed a certain level of redundancy, and the onboard navigation guidance control system detected an abnormality, spacecraft drifted eastwards and descend slowly. During this process, LEV-1 and LEV-2 (SORA-Q) were separate at an altitude of about 5m. Finally, spacecraft landed with slower rate of descent than the specified range. However, landing conditions such as the lateral velocity and attitude exceeded the specified range and produced a large attitude fluctuation after landing that resulted in a settled attitude different to expected.
Details in the descent and landing operation will be reported in the presentation, with the post landing operations and these results.