Japanese lunar lander crashes due to a software error

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A review of data showed that the software guiding the descent appeared to lose track of the landers’ altitude as it passed over the rim of a crater on the lunar surface about two miles higher than the surrounding terrain.

The software incorrectly concluded that the sensor was defective and rejected height readings that were correct.

The engine, altimeter and other hardware worked properly, indicating that the overall design of the spacecraft is good. Software fixes are easier to perform than major hardware revisions.

“This is not a hardware failure,” Ryo Ujiie, Ispace’s chief technology officer, said at a news conference Friday. “We don’t need to adjust the hardware side.”

However, the glitch pointed to shortcomings in Ispace’s testing of the spacecraft’s landing software, which was developed by Draper Laboratory of Cambridge, Massachusetts.

A decision to change the landing site, after the spacecraft design was finalized in early 2021, most likely contributed to the crash.

Originally, Ispace officials had chosen Lacus Somniorum, a flat plain, as the landing site. But then they decided that Atlas, an impact crater more than 50 miles wide, would be a more interesting destination.

That meant the landing software wasn’t designed to handle the change in altitude as the spacecraft passed the crater rim, and simulations hadn’t caught that overview.

On Tuesday, NASA has released images taken by his Lunar Reconnaissance Orbiter which appeared to show the crash site.

Background: a bumpy path to the moon.

A mix of private companies, organizations and government space agencies have attempted to return to the Moon in recent years. But landing on the lunar surface proved more difficult than many expected.

The Beresheet lander, from an Israeli nonprofit called SpaceIL, launched to the moon in 2019, but crashed. The Indian Space Research Organization also attempted to land a lunar spacecraft in the same year, and that vehicle, the Vikram, also crashed.

Only China has landed a robotic spacecraft on the moon recently, with three successes in three attempts over the past decade.

What’s Next: Try, try again.

Takeshi Hakamada, Ispace’s founder and CEO, said the schedule for the company’s next two missions — with a nearly identical lander next year and a larger spacecraft to the far side of the moon in 2025 — remains largely unchanged.

“We have a very clear picture of how to improve our future missions,” said Mr. Hakamada.

Ispace had taken out insurance for the lander and the financial impact on the company would be minor, Mr Hakamada said.

More spacecraft will be launched to the moon later this year. As part of a NASA program hiring private companies to deliver scientific instruments to the moon, Astrobotic Technology of Pittsburgh and Intuitive Machines of Houston will send spacecraft to the moon later this year.

Also the Indian Space Agency announced this week that Chandrayaan-3, a follow-up to its 2019 lunar landing attempt, could launch as early as July 12.