Later today, a Japanese company will be attempting a feat which few have achieved successfully: it will try to gently touch down its Resilience lander on the moon’s surface as part of its Hakuto-R Mission 2. Given that humans landed on the moon over 50 years ago, you might assume that moon landings today are easy, but you’d be wrong — as plenty of recent history shows.
ispace’s previous mission, Hakuto-R Mission 1, was launched in December 2022 but failed its lunar landing in April 2023. That spacecraft did slow to a speed of less than one meter per second and did get into a landing position, but it crashed into the moon’s surface due to problems with the spacecraft’s altitude measurement.
This time, the company will be hoping for a better result.
“Just over two years ago, on April 26, 2023, ispace, operating Hakuto-R Mission 1, became the first private company in the world to attempt a lunar landing. While the mission achieved significant results, we lost communication with the lander just before touchdown,” said Takeshi Hakamada, CEO of ispace. “Since that time, we have drawn on the experience, using it as motivation to move forward with resolve. We are now at the dawn of our next attempt to make history.”
How landings have gone wrong before
The challenges of landing on the moon are many, and it takes just one thing to go wrong for a landing to fail. That’s what happened to ispace with its previous landing attempt, which occurred due to the complex topography of the moon’s surface.
The surface of the moon is covered in craters caused by impacts with meteors and other bodies, some of which are miles wide. While the Earth has experienced similar periodic impacts, on the moon these craters stay present for much longer because there is no atmosphere and no wind to erode them. That means sharp edges, jagged shapes, and steep cliffs.
It was one of these cliffs at the rim of the crater which cratered the previous landing. Passing over a cliff nearly two miles deep, the lander’s altitude measurement showed a dramatic jump, and its software assumed that this data must be incorrect so it was ignored. The result of this was that the lander thought it was on the surface when it was still 3 miles above it, and so it cut its engines causing it to plummet straight down and crash.
This goes to show how tricky the moon can be due to its surface geography. But it isn’t just cliffs which can be a problem there.
When Intuitive Machines landed its Odysseus lander on the moon in 2024 it made history as the first US spacecraft to land there since the Apollo missions, but it also had landing problems and ended up settling on the surface at a tilted angle. That limited its lifespan as it couldn’t collect enough solar power via its panels to keep operations going. In that case, the problem happened when the landing didn’t occur in exactly the landing zone which had been planned, but rather at a site around one mile away which had higher elevation. With the wrong elevation data, the leader skidded across the surface, damage its leg, and gently tipped over once it came to a standstill.
Intuitive Machines’ second attempt at landing with another version of the spacecraft earlier this year was even less successful, as the lander ended up fully on its side and totally unable to collect solar power. Then, it seemed that the lander may have caught a leg on the edge of a crater or on a boulder, causing it to tip over. As well as all the craters on the moon, there are also many loose boulders, some of which are more than 10 meters across.
It’s extremely hard to detect these kinds of topographical challenges from orbit, as landers have to begin their descent processes far above the moon’s surface to give them enough time to slow down so they can set down gently on the surface. They can’t detect relatively smaller obstacles like boulders or crater edges until they are closer to the surface, by which time they may not be able to maneuver to avoid them.
And finally, there’s the fact that the landing procedure needs to be perform with second-time accuracy. The Israeli company SpaceIL had an issue with its Beresheet lander in 2019, when it lost contact with its spacecraft for just a few seconds during landing so a part could be rebooted. That few seconds without contact was enough for the engines to stop firing during the descent, meaning the craft couldn’t slow itself quickly enough and smashed hard into the moon’s surface.
A success story
With all these partial or total failures, it’s notable that there has been one success when it comes to a private company landing on the moon. Firefly Aerospace’s Blue Ghost mission touched down safely on the moon’s surface earlier this year, marking a big check for the company’s first landing attempt and allowing the lander to complete a successful two-week mission.
That lander made use of technology similar to that NASA uses for its Mars landings, called terrain relative navigation, in which cameras on the underside the spacecraft take images of the surface as it descends. An onboard computer then compares these images to onboard maps to select a safe landing spot, allowing the spacecraft to land itself autonomously.
So it can be done, and has been done. But with the moon’s tricky surface making every landing a challenge, we’ll have to wait and see whether ispace can replicate that success. You can tune into the livestream of the ispace landing in a few hours’ time to see how it does.
