Japan’s SLIM moon lander survives a second brutal lunar night

SLIM, Japan’s first successful lunar lander, isn’t going down without a fight. After making history—albeit upside down—in January, the Smart Lander for Investigating Moon continues to surprise mission control at Japan Aerospace Exploration Agency (JAXA) by surviving not one, but now two brutally frigid lunar nights.

“Last night, we received a response from #SLIM, confirming that the spacecraft made it through the lunar night for the second time!” JAXA posted to X on Wednesday alongside a new image of its likely permanent, inverted vantage point near the Shioli crater. JAXA also noted that, because the sun is currently high above the lunar horizon, SLIM’s equipment is currently extremely hot (212-degrees Fahrenheit or so), so only the navigation camera can be used for the time being.

Last night, we received a response from #SLIM, confirming that the spacecraft made it through the lunar night for the second time! Since the sun was still high and the equipment was still hot, we only took some shots of the usual scenery with the navigation camera. #GoodAfterMoon pic.twitter.com/5BjIr7vxMG

— 小型月着陸実証機SLIM (@SLIM_JAXA) March 28, 2024

Based on their newly acquired data, however, it appears that some of the lander’s temperature sensors and unused battery cells are beginning to malfunction. Even so, JAXA says “the majority of functions that survived the first lunar night” are still going strong after yet another two-week stretch of darkness that sees temperatures drop to -208 Fahrenheit.

It’s been quite the multi-month journey for SLIM. After launching last September, SLIM eventually entered lunar orbit in early October, where it then spent weeks rotating around the moon’s surface. On January 19, JAXA initiated SLIM’s landing procedures, with early indications pointing towards a successful touchdown. After reviewing lander data, JAXA confirmed the spacecraft stuck the landing roughly 180-feet from an already extremely narrow 330-feet-wide target site—thus living up to SLIM’s “Moon Sniper” nickname.

The historic moment wasn’t a flawless mission, however. In the same update, JAXA explained that one of its lander’s main engines malfunctioned as it neared the surface, causing SLIM to tumble over, ostensibly on its head. In doing so, the craft’s solar panels now can’t work at their full potential, thus limiting battery life and making basic functions much more difficult for the lander.

JAXA still managed to make the most of its situation by using SLIM’s sensors to gather a ton of data on the surrounding lunar environment, as well as deploy a pair of tiny autonomous robots to survey the lunar landscape. On January 31, mission control released what it cautioned could very well be SLIM’s last postcard image from the moon ahead of an upcoming lunar night. The lander wasn’t designed for a lengthy life even in the best of circumstances, but its prospects appeared even dimmer given its accidental positioning.

Roughly two weeks later, however, SLIM proved it could endure in spite of the odds by booting back up and offering JAXA another opportunity to gather additional lunar information. A repeat of JAXA’s same warning came a few days later—and yet here things stand, with SLIM still chugging along. From the start, researchers have employed the lander’s multiple tools, including a Multi-Band Camera, to analyze the moon’s chemical composition, particularly the amounts of olivine, ““will help solve the mystery of the origin of the moon,” says JAXA.

At this point, it’s anyone’s guess how much longer the lander has in it. Perhaps it’s taking a cue from NASA’s only-recently-retired Mars Ingenuity rotocopter, which lasted around three years longer than intended.