The reason why Japanese space company ispace’s lunar lander failed to land on the moon last month has been revealed. It turned out that the main cause was a malfunction of the altitude sensor due to the unusual topography of the landing site. iSpace intends to take on the next challenge after making software modifications.
On the 26th of this month, iSpace announced the results of an accident investigation into the lunar lander ‘Hakuto-R M1’. As a result of the analysis of flight data, it was revealed that the cause was that the altitude of the plane was incorrectly recognized due to a software problem when trying to land on the moon.
The Hakuto-R M1 was launched on December 11 last year on a SpaceX Falcon 9 rocket from the Cape Canaveral Space Force Base in Florida, USA. So far, only the United States, Russia, and China have succeeded in developing a lunar lander, and no private companies have succeeded. If this attempt were successful, Japan could become the fourth country in the world to successfully land on the moon and the first country to successfully develop a private lunar lander.
However, on the 26th of last month, Hakuto-R M1 crashed due to a loss of communication while trying to land in the Atlas crater on the far side of the moon. At the time, it was not confirmed whether it was a simple communication loss or a failed landing, but the United States National Aeronautics and Space Administration (NASA) confirmed the landing failure by finding traces of the lander crashing and breaking.
According to iSpace, the lander started landing at an altitude of 100 km and slowed to 5 km per hour according to the plan. However, when it reached an altitude of 5 km, an error occurred in the software. The landing control software was not measuring the height of the lander correctly. The lander then ran out of fuel and crashed at 320 km/h.
The software pointed to a lack of sensor due to the surrounding terrain as the reason why the software was not determining the height of the lander properly. The crater of Atlas, where he attempted to land, is surrounded by cliffs that rise about 3 km above the surrounding land.
Sensors mounted on the lander were measuring height incorrectly as it passed this location, and there was a large discrepancy between the height measured by the sensors and the height projected by the lander. It is explained that the software identified a malfunction of the sensor and did not accept the height measured by the sensor during the subsequent landing process, leading to the accident.
Originally, the landing site of the Japanese lander was ‘Lacus Somniorum’, a frontal area in the north-east of the lunar surface, but after the design of the lander was completed, it was changed to the Atlas crater. As a result, landing software was used that did not measure the topography of the crater properly, and it is said that this defect is not expected during the simulation process.
As it was analyzed that there was no problem with the iSpace hardware, the plan is to try to land on the moon again after a simple software fix. The next landing attempt is scheduled for next year. In addition, the plan to send a lander to the far side of the moon in 2025 will be promoted without any change.
“We have very clear plans on how to improve our next attempt,” said Takeshi Hakamada, CEO of ispace. “This failure has little effect on the company’s finances.”
