SLIM Survives Another Lunar Night

SLIM Survives Another Lunar Night

The Japanese space agency’s SLIM lunar lander defied the odds again, surviving not just one, but two bitter cold lunar nights and sizzling hot lunar days. The Smart Lander for Investigating Moon has sent back another new image from its navigation camera two months after a sporty landing that initially suggested its lifetime would be sharply limited.

The Japan Aerospace Exploration Agency (JAXA) broadcast the astonishing news of SLIM’s survival on X (formerly Twitter), including a new image from its navigation camera.

SLIM set down on the lunar surface on January 19, 2024 Eastern Standard Time (January 20 in Japan), but after losing an engine during descent it landed upside down with most of its solar panels facing away from the Sun.

Image of Japan’s SLIM lander, upside down on the Moon, taken by the tiny Lunar Excursion Vehicle-2 (LEV-2) that was ejected from SLIM just before it reached the surface. Credit: JAXA/ISAS post on X (@ISAS_JAXA-EN) January 25, 2024.

Without sufficient power, the lander was expected to operate for only a short period of time, but sent back images from one of its navigation cameras as well as a partial image using its more capable Multi Band Camera (MBC).

Engineers hoped that as the Sun angle changed in subsequent days enough sunlight could reach the panels to allow further imagery. Indeed, that’s exactly what happened and before the 14-day lunar night descended they obtained the rest of the MBC scan.

SLIM is one of a new generation of comparatively inexpensive lunar landers that rely only on solar cells, not radioistopes, for power and warmth. The trade-off for the lower cost is a short lifetime since batteries and electronics are not designed to survive 14 days of frigid cold about -250°C (-418°F).

Two other new-generation spacecraft have successfully landed on the Moon in the past year. As expected, India’s Chandrayaan-3 and the U.S. Odysseus, or Odie, built by Intuitive Machines as part of NASA’s Commercial Lunar Payload Services (CLPS) program, did not wake up after their lunar nights. Intuitive Machines acknowledged Odie’s fate in a series of posts on X.

Only SLIM again responded to commands and not just after the first lunar night, but now after a second.

The imagery being acquired is only from a navigation camera, not the MBC, and since the camera cannot be moved and the surface of the Moon doesn’t change, it looks much the same.

As JAXA said in one of its posts on X (translated by Google): “There is no rain or wind on the moon, so if you take a photo taken in the same direction, the arrangement of rocks and topography will hardly change. The crater that I targeted when I landed has had the same shape since ancient times. Since you can’t move the navigation camera, you’ll probably continue to get photos where nothing is moving at all, but keep an eye out for changes in the length of the shadows!”

JAXA said that although “some temperature sensors and unused battery cells are starting to malfunction,” most of the “functions that survived the first lunar night” also survived the second.


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