Beating incredible odds, Japan's SLIM lunar lander came back to life after surviving the intense dark and cold of the Moon's night. On February 25, JAXA confirmed that it had temporarily reestablished communications with the robotic spacecraft.
Spacecraft have been landing on the Moon for over half a century, but very few have survived the dark and cold of the lunar night. When the sun sets and the 14-day night begins, there is no light for solar panels to charge batteries and the temperatures plummet to -208 °F (-133 °C). Such intense, long-lasting cold is brutal on spacecraft systems – especially electronics and batteries. The usual outcome of such an ordeal is a dead lander and a terminated mission.
Some spacecraft and instrument packages have survived this, but these have had a radio-thermal generator aboard to provide either power or just heat to keep the equipment from freezing. However, SLIM, which landed on January 19, 2024, didn't have anything like this. Worse, when it landed on the lunar surface, it bounced and ended up resting on its nose, which kept it from charging its battery except for the short period when the sun was in just the right position.
JAXA engineers had hoped that SLIM might revive when the lunar day returned, but that was more an expression of hope and optimism than anything else. However, that didn't keep the space agency from sending messages to SLIM in anticipation of a reply. Then, on February 25, 2024, a response came back, showing that SLIM had come back to life.
This was particularly surprising because not only had SLIM survived the night, but it was only well into the lunar day that the battery was able to charge enough to bring the communication system online. This suggests that modern electronics are much more robust than previously.
Unfortunately, this turned out to be a mixed blessing. Instead of dealing with dark and cold, SLIM now has to contend with light and heat. With the thermometer pegging at 250 °F (121 °C) in daylight, the systems overheated and the radio link was lost. The hope is that as the lunar afternoon progresses, cooler temperatures will allow the lander to come back online.
Source: JAXA