Japan’s SLIM Lunar Lander Back Online After Precise but Awkward Landing

JAXA SLIM lander
JAXA created this render showing how SLIM landed on the Moon a bit askew.

Last week, Japan became the fifth country to land a spacecraft on the Moon successfully. However, the historic accomplishment had its challenges. The Japanese Aerospace Exploration Agency’s (JAXA) Smart Lander for Investigating Moon (SLIM) landed upside-down on the lunar surface, preventing the lander from recharging its batteries with its included solar panels.

As has been demonstrated by numerous lunar landing failures, successfully touching down on the Moon is exceptionally challenging. However, given that the Soviet Union successfully put Luna 2 on the Moon in 1959 and NASA famously landed men on the Moon in 1969, it may seem odd that scientists today still struggle with lunar missions.

Japanese private company iSpace has failed, and so too has private American company Astrobotic Technology. Israel, Russia, and the United Arab Emirates have failed attempts. India made it last year after multiple unsuccessful missions.

As The Guardian explains, a significant challenge is that while the Moon has gravity — about one-sixth of Earth’s gravitational force — it doesn’t have an atmosphere. Without an atmosphere, a lunar landing requires precise engine control to land on the Moon safely. Unlike landing on Mars, a parachute is useless on the Moon.

For similar reasons, it is also difficult to test a lunar lander on Earth. And it’s expensive, which is always a complicating factor.

While JAXA’s SLIM lander face-planted on the Moon, it landed with unprecedented precision regarding where it wound up. The team missed the targeted touchdown location by only 180 feet (55 meters), besting its goal of landing within 100 meters of its target.

For reference, the Apollo 11 mission’s Eagle lunar lander performed an elliptic landing with a range of 20 kilometers downrange and a five-kilometer cross range. This helps put SLIM’s precise soft landing in an impressive context.

The issue with the landing, which was captured by a pair of baseball-sized camera robots, was that SLIM’s solar panels were facing the wrong direction.

After allowing the lander to work with available battery life for a couple of hours after it touched down on January 20th, JAXA opted to shut it down and wait for a change in sunlight direction to work in its favor — as it did over the weekend.

Once revived by the Sun, SLIM captured a photo of a nearby rock, which JAXA has named “Toy poodle.”

SLIM is paving the way for future lunar exploration and despite landing a little awkwardly, demonstrates that precise lunar landing is possible.