Laser rangefinder problems blamed for second ispace lunar lander crash
By Jeff Foust, Space News - June 24, 2025
https://spacenews.com/laser-rangefinder-problems-blamed-for-second-ispace-lunar-lander-crash/
… The company then turned its attention to the laser rangefinder. The reviews found no evidence that the laser rangefinder was improperly installed, he said, leading ispace to conclude that the performance of the unit had degraded in some way compared to pre-flight tests. Several factors could cause that degradation, including lunar surface conditions that reduced the amount of laser light reflected back to the lander, lower power of the laser, reduced performance at higher velocities or effects from the space environment, such as vacuum or radiation.
“We are currently unable to further narrow them down,” he said through an interpreter of those potential causes, “or whether the anomaly was due to a single factor or a combination of multiple factors.” Hitachi emphasized that the cause of the Resilience landing was different from the company’s first mission in 2023, when a software problem caused the lander to think it was near the surface when it was in fact at an altitude of five kilometers, hovering until it exhausted its fuel and crashed. That software worked well on Resilience, he said.
The first lander did not have any problems with its laser rangefinder, but he said that Resilience used a different model because the unnamed supplier of the device no longer made the version used on the initial mission. ….