This video details the findings from a press conference regarding Japan's iSpace lunar lander's unsuccessful attempt in June. It reveals that the lander was within four seconds of a successful touchdown after a five-month journey. The primary cause of failure was identified as the laser rangefinder (LIDAR) taking too long to acquire the lunar surface, specifically not locking on until the lander was at 650 meters altitude while descending at 66 meters per second. This delay meant the lander did not have the necessary 900 meters to decelerate and stop, resulting in a shortfall of 250 meters that was covered in less than four seconds. Ground testing had anticipated LIDAR lock-on at 1.5 kilometers, highlighting the significant discrepancy in real-world performance.
Summarizing the iSpace Moon Landing Attempt: A Near Miss
0:03 Unsuccessful Landing Confirmed: Japan's iSpace moon landing attempt in June was unsuccessful, but new details reveal how close it came.
0:12 Within 4 Seconds of Success: After five months of travel, the lander was within 4 seconds of a successful landing.
0:21 Problem Identified: LIDAR Delay: The core issue was that the laser rangefinder (LIDAR) took too long to acquire the moon's surface.
0:32 Critical Descent Parameters: When the LIDAR finally acquired the lunar surface, the lander was at 650 meters altitude, descending at a high speed of 66 meters per second.
0:43 Insufficient Deceleration Distance: Calculations show the lander needed 900 meters to stop from 66 meters per second, but only had 650 meters available, a difference of 250 meters.
0:54 The 4-Second Gap: At 66 meters per second, the lander covered the critical 250-meter shortfall in less than 4 seconds, highlighting the narrow margin of failure.
0:59 Discrepancy in LIDAR Performance: Ground testing had predicted the LIDAR would lock on by 1.5 kilometers, but in reality, it didn't get a return until 650 meters, making it too late for the engines to achieve a soft landing.