It’s been a rocky road for Japan’s SLIM lunar lander ever since it touched down on the Moon’s surface. Having made a record-breaking landing with a bump that jeopardized its entire mission, it made a comeback, rejuvenated by the Sun’s rays. But now, it faces its toughest challenge yet: surviving the freezing lunar night. This may or may not be the end of the mission, but before it slipped into power-down mode it made sure to grab some final incredible images of the Moon’s surface to send home.
On January 19, after a nail-biting nearly two-hour wait, Japan confirmed its Smart Lander for Investigating Moon (SLIM) had successfully soft-landed on the Moon, making Japan the fifth nation to do so. However, from the get-go, the team on the ground knew something was up. It had nailed its precision landing inside the Shioli Crater and deployed its two rovers – two of its main mission goals – but the lander’s solar panels were not harvesting sunlight and it was running on just batteries.
An incredible photo taken by one of the rovers revealed the lander had landed on its nose, meaning the solar panels were not in the right position to pick up the Sun’s rays. There was a good chance, however, that if they waited for the Moon to go around the Earth, the change in angle would mean the sunlight could reach the lander's solar cells and start charging. Nearly 10 days after it landed, it did indeed come back to life, reestablishing contact and sending back new photos.
Since then, the Japan Aerospace Exploration Agency (JAXA) has been scanning the lunar surface and taking images using SLIM's Multi-Band Camera (MBC) to analyze the rocky composition, even managing to observe more targets than planned. However, yesterday the space agency confirmed SLIM has powered down as it has entered the dormancy period during the two-week lunar night, where no sunlight will reach its panels.
Now, JAXA will have to wait out the long lunar night, which lasts around 14.5 Earth days, and where temperatures can plummet to -130°C (-208°F). If SLIM survives, light and temperature conditions should improve around February 15 and JAXA will try and make contact again.
If it does, then it can continue with its science missions, exploring the surrounding area of Shioli crater, which sits in the larger Cyrillus crater on the near side of the Moon. If it doesn't, then it has already made history with the most precise landing on another world. SLIM aimed to land within 100 meters (330 feet) of its target area – for context, Perseverance's landing target area on Mars was 7.7 kilometers by 6 kilometers (4.8 by 4.1 miles) – and JAXA has since confirmed it landed within just 55 meters (180 feet), a phenomenal achievement.
The lunar night is not historically kind to landers, and many are not built to last it. If SLIM wakes up in two weeks' time, its mission has already been fulfilled – but it will continue to observe and analyze the chemical composition of the rocks it sees on the lunar surface to help solve the mystery of the origin of the Moon.