Japan's iSpace Lunar Lander Crashes: A Post-Mortem Analysis

iSpace's Second Lunar Landing Attempt

• 🇯🇵 Japan's iSpace experienced its second lunar crash, with the spacecraft failing to achieve a soft landing on the moon.
• 💡 The mission, initially a competitor for the Google Lunar XPRIZE, now operates on sponsor funding and paid payloads.
• 🚀 A micro-rover was on board, and while it technically landed, it is unable to drive due to the crash.

Mission Trajectory and Optimization

• 🛰️ The spacecraft launched in January and took a long, circuitous route to the moon, utilizing the Earth-Moon Lagrange point to save propulsion fuel.
• ⚙️ Engineering decisions prioritized efficiency and low cost, enabled by modern technology, but also made the spacecraft dependent on it.
• 📉 The mission aimed for a landing site near the lunar north pole, employing a complex braking and descent sequence.

Descent and Failure Analysis

• 📈 During the braking burn, the spacecraft was traveling at approximately 600 km/h at an altitude of 4 km.
• ⚠️ Issues arose during the pitchover phase, with telemetry showing anomalies and a simulation mode indicating a loss of real-time data.
• 💥 The spacecraft descended too rapidly, at about 60 m/s, exceeding its deceleration capabilities, leading to a crash.
• ❓ The primary cause cited was a failure of the lidar to lock onto the surface in time during terminal descent, preventing adequate deceleration.

Comparison to Past Landings

• 🌕 Unlike older missions like Surveyor, which landed directly, iSpace used a more complex, sideways approach to save fuel.
• ⚖️ This modern approach, while efficient, is more reliant on precise sensor data, which was lacking.
• 📉 The previous Hakuto mission also failed due to sensor issues, where an altitude reading over a cliff was rejected, leading to a crash at a higher-than-expected altitude.

Amateur Tracking and Impact Assessment

• 📡 Amateur radio astronomers tracked the spacecraft's descent using Doppler shift measurements.
• 📉 Analysis of this data suggests the lander hit the surface at approximately 30-40 m/s (around 100 km/h).
• 🔍 It is expected that the Lunar Reconnaissance Orbiter will find a scar on the surface rather than a crater, indicating a relatively monolithic impact structure.
• 🙏 The speaker expresses hope for iSpace's future attempts and wishes them success.