The private Japanese moon lander Hakuto-R crashed in late April during its milestone landing attempt because its onboard altitude sensor got confused by the rim of a lunar crater.
Representatives of Tokyo-based company ispace, which built the spacecraft, revealed that the unexpected terrain feature led the lander’s onboard computer to make a decision that its altitude measurement was fallacious and rely as a substitute on a calculation based on its expected altitude at that time within the mission. Consequently, the pc was convinced the probe was lower than it actually was, which led to the crash on April 25.
“While the lander estimated its own altitude to be zero, or on the lunar surface, it was later determined to be at an altitude of roughly 5 kms [3.1 miles] above the lunar surface,” ispace said in a press release released on Friday (May 26). “After reaching the scheduled landing time, the lander continued to descend at a low speed until the propulsion system ran out of fuel. At the moment, the controlled descent of the lander ceased, and it’s believed to have free-fallen to the moon’s surface.”
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The corporate said in a briefing that an insufficient consideration of terrain topography across the landing side contributed to the failure, partly as a consequence of a landing site change several months prior to the mission’s liftoff.
The lander, which launched in December 2022 on a SpaceX Falcon 9 rocket, was to land on April 26 on the ground of the 54-mile-wide (87 km) Atlas Crater within the Mare Frigoris (“Sea of Cold”) region of the moon‘s near side. Earlier this week, NASA’s Lunar Reconnaissance Orbiter spotted the Hakuto-R wreckage near the intended landing site.
If successful, Hakuto-R would have been the primary privately operated moon lander to perform a lunar landing. Up to now, only NASA, China and Russia have soft-landed spacecraft on the moon’s surface.
Ispace stressed that the mission successfully accomplished eight of its nine mission milestones and only failed in the ultimate stages of its powered descent. The mishap, the corporate’s representatives said, won’t affect the planned launches of ispace’s second and third missions in 2024 and 2025, respectively.
Since the failure was traced right down to a software issue, the longer term missions won’t require a hardware redesign.
“Now, we’ve got been in a position to discover the difficulty throughout the landing and have a really clear picture of improve our future missions,” Takeshi Hakamada, Founder and CEO of ispace, said within the statement.