Lukasz Lukasiewicz, Shutterstock
Japan’s Moon lander, the Smart Lander for Investigating Moon (Slim), has resumed its mission, days after its landing was overshadowed by the discovery that its solar cells were not generating power, potentially leaving it stranded on the lunar surface.
On 20 January, Japan became the fifth country to soft-land a spacecraft on the Moon, following the Soviet Union, US, China and India. Slim, nicknamed the ‘Moon Sniper’, was designed with unprecedented precision in mind – it aimed to land within 100m of its target on the lunar surface, rather than within several kilometres.
Several comparable projects had failed in the past years: in April 2023, a lunar lander built by Japanese start-up ispace lost contact in the final moments of its descent and crashed into the surface of the moon.
After releasing its two lunar rovers, landing safely just 55m from its target, and establishing communications ground-based stations, however, the Japan Aerospace Exploration Agency (Jaxa) realised that Slim’s solar cells were not generating power, possibly because the spacecraft had suffered engine problems and landed at the wrong angle. Its solar panels ended up facing west instead of upwards, limiting its ability to generate electricity from sunlight.
Jaxa took measures to preserve the lander’s power reserves, disconnecting its battery three hours after the landing to preserve its power for a possible restart. Officials said that they hoped a shift in the angle of sunlight might make it possible to start electricity generation, commenting last week that: “If sunlight hits the Moon from the west in the future, we believe there’s a possibility of power generation, and we’re currently preparing for restoration.”
Now, Jaxa has issued an update, writing on X (formerly Twitter): “Last evening we succeeded in establishing communication with Slim, and operations resumed!”
According to the tweet, scientific observations were immediately started, with Slim’s onboard multi-band camera producing an image of rocks on the surface of the Moon. Jaxa posted a photo of a rock that has been nicknamed ‘toy poodle’ by the agency.
A Jaxa spokesperson told Agence France-Presse that operations were able to resume, “presumably because power generation resumed in its solar battery as it received sunlight”.
“We will prioritise what we can do now – observing a collecting information – rather than adjusting Slim’s position, since adjusting the position could lead to a worse situation.”
“The daytime [in Slim’s location on the Moon] will last until around the end of January, and it will be at night from around February.” Previously, Jaxa indicated that Slim was not designed to survive a long lunar night.
Slim will proceed with its mission to analyse the composition of rocks near its landing site, where the Moon’s mantle is thought to be exposed at the surface. This could help shed light on the Moon’s possible water resources.
