Unexpectedly, Japan’s Moon lander has survived a freezing two-week lunar night and can continue its operation. On February 25th, the Japanese Aerospace Exploration Agency, or JAXA for short, announced they had regained contact with their record-breakingly accurate Moon lander that landed on January 19th on the social media platform X, formerly known as Twitter. Communication with the Moon lander was quickly ceased as operators of the spacecraft were worried about increased temperatures at the point of landing disabling functional parts on the lander.
On January 31st, JAXA shut down their Smart Lander for Investigating Moon, also known as SLIM, right before the lunar night came for the lunar lander. Nighttime on the Moon lasts for about 14 days and can get as cold as -208 degrees Fahrenheit or -133 degrees Celcius. SLIM was not expected or designed to survive this 2-week long night, however, SLIM has come out mostly or completely undamaged
JAXA has confirmed that the communication system, onboard computer, and solar panels are operational and has commanded the death-defying spacecraft to resume taking photos of its surroundings. India’s Chandrayaan-3 Moon lander, which landed on the Moon in August of 2023, had to shut down during the Moon’s night like SLIM. However, Chandrayaan-3 did not wake up after the lunar night had passed.
This is not the first time SLIM had a close call with an early end to its mission. On January 19th, during SLIM’s lunar descent to the surface, one of two primary engines equipped with SLIM stopped functioning properly. SLIM ended up landing about 55 meters away from its designated landing point, a new record for the accuracy of spacecraft landing on the Moon and making Japan the 5th country to successfully land on the Moon. This unprecedented accuracy gave SLIM the nickname “Moon Sniper.”
On the surface of the Moon, SLIM took several photos of rocks surrounding it and its landing site, the Shioli crater. Upon landing, SLIM’s solar panels could not generate electricity for the Moon lander and controllers at JAXA could not figure out why. During descent, two small rovers were ejected from SLIM. One rover had camera equipment, while the other carried communications equipment. The rover with camera equipment took photos of SLIM which were sent back to JAXA headquarters by the other rover with communications equipment. The photos displayed SLIM in an incorrect landing position than what it was meant to land in. This incorrect position was a result of one of the two primary engine failures during lunar descent.
The position put SLIM’s solar panels facing away from the sun, incapable of generating any electricity for the stranded lander. All was not hopeless for Japan’s lunar lander though, given enough time light could hit SLIM’s solar panels if the Sun were positioned correctly. To conserve power, JAXA shut off SLIM until it could begin recharging its battery once again. About 9 days later, SLIM awakened with the sunlight hitting its solar panels and its batteries charging. This allowed SLIM to continue its mission for a limited amount of time due to the upcoming lunar night which was only a few days away.
Despite SLIM’s good fortune so far, operators of the spacecraft have to contend with temperatures that SLIM was not designed for, as high as 250 degrees Fahrenheit or 121 degrees Celcius.
