SLIM Beats the Odds Again

SLIM Beats the Odds Again

This morning brought the good news that Japan’s lunar lander, SLIM, defied the odds yet again and has resumed tranmissions after surviving the bitter cold lunar night. The Smart Lander for Investigating Moon had a rough landing and although ground controllers were able to get data and images back, the solar-powered lander was not expected to operate again after sundown three weeks ago.

The Japan Aerospace Exploration Agency (JAXA) posted the news on X this morning Eastern Standard Time (EST) saying that it sent a command to SLIM and received a response, but they quickly stopped because the temperature of the equipment was “very high.”


SLIM’s successful landing on January 19 EST (January 20 in Japan) was the first time it beat the odds. One of its descent engines failed and the nozzle fell off. Then it tipped over when it reached the surface and some of the solar cells needed to provide power to the payloads, including communications systems, were pointing in the wrong direction. JAXA waited a few days until the Sun angle changed and were able to restore communications and get back data and images.

On February 1 EST, however, lunar night descended. One side of the Moon always faces Earth and the other always faces the Sun, but each side experiences 14 days of sunlight and 14 days of darkness as the Moon orbits Earth every 28 days.

SLIM is one of a new type of comparatively inexpensive lunar landers that rely only on solar cells for power instead of radioisotope power supplies like those used by Soviet and U.S. landers in the 1960s and 1970s and China more recently. Radioisotope sources not only provide power, but keep a spacecraft’s electronics warm. With temperatures dropping to -250°C (-418°F) at night and less robust electronics, the new solar-powered landers are not expected to make it through the night.

But SLIM has, in fact, resumed operations. JAXA posted a new image today that it said was taken by a navigation camera “during the SLIM overnight operation.”

How long it will operate is an open question. Stay tuned.

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