Japanese company ispace announced that a software glitch caused its lunar lander to crash during its landing attempt last month. The onboard computer disregarded altitude information from a laser rangefinder on the lander as it passed over a crater rim, leading the lander to conclude it was on the surface when it was still five kilometers above it. The company’s investigation found that the onboard computer was not programmed to expect the change in altitude and ignored the data from the laser rangefinder on the assumption that the instrument had malfunctioned. The lander crashed into the surface at a speed of more than 100 meters per second.
As detailed in SpaceNews, a software glitch caused the HAKUTO-R M1 lunar lander to crash during its landing attempt last month. Japanese company ispace made the announcement on May 26 after conducting an investigation into the failed landing.
The company stated that the onboard computer did not properly determine the lander’s altitude due to a laser rangefinder malfunction. As the lander passed over a crater rim, the computer disregarded altitude information from the rangefinder and concluded that the lander had landed on the surface when it was still five kilometers above it.
During an online briefing, ispace executives explained that the landing was initially going as planned, with the altitude calculated by an inertial measurement unit converging with measurements from the laser rangefinder. However, the readings diverged once the lander passed over the rim of Atlas Crater, causing the measured altitude to increase by three kilometers.
Chief technology officer of ispace, Ryo Ujiie, stated that the onboard computer ignored the data from the laser rangefinder on the assumption that the instrument had malfunctioned. This was a deliberate choice to make the control system more robust against a sensor hardware failure. However, the sensor had not failed, and the lander continued to descend under its thrusters until it ran out of propellant and crashed into the surface at a speed of over 100 meters per second.
An image from NASA’s Lunar Reconnaissance Orbiter (LRO) spacecraft, released on May 23, revealed the impact site and several pieces of debris from the spacecraft. The impact zone was just outside the predicted landing site within Atlas Crater, although Ujiie declined to specify how far from its planned location the lander crashed.
As detailed in Ujiie, a factor in the crash was a change in landing sites made after the mission completed its critical design review in February 2021. The mission was originally supposed to land in Lacus Somniorum, a basaltic plain with few craters. However, the company changed the landing site “to maximize the benefit of the mission” without sufficiently testing the change before launch.
This incident serves as a reminder of the challenges of space exploration and the importance of rigorous testing and quality control. While setbacks such as this are disappointing, they also provide valuable lessons for future missions and help improve the safety and success of space exploration endeavors.
To wrap up, ispace’s HAKUTO-R M1 lunar lander crashed during its landing attempt due to a software glitch that caused the onboard computer to ignore altitude information from a laser rangefinder. The lander continued to descend until it ran out of propellant and crashed into the surface. The incident highlights the importance of thorough testing and quality control in space exploration.
