Japan SLIM chance of sun on the Moon

There is a SLIM chance of sun on the Moon at some point, which is an odd thing to say but there is a good reason. The Smart Lander for Investigating Moon (SLIM) spacecraft was launched by Japan in September 2023 and it successfully landed on the moon on January 19th, 2024, at 15:20 p.m. GMT (10:20 a.m. ET.).

Three hours after SLIM touched down on the moon, the lander was shut off to save power. JAXA (Japan Aerospace Exploration Agency) says the mission is not yet over. Everything could be resumed so long as there is a chance of sun on the moon. Or, rather, if sunlight hits the moon at the right place.

SLIM chance of sun on the moon when the lander points the wrong way

It didn’t take engineers long to realise that solar cells on the SLIM lander could not generate power, because they were pointing west and away from the sun.

The JAXA mission team is still hopeful that the situation can improve, so long as lighting conditions improve on the moon in the way they hope.

However, the mission team is hopeful the situation could improve as lighting conditions shift.

“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,”
JAXA Statement

Japan’s SLIM moon mission is nicknamed “Moon Sniper” for its use of precision-landing technologies. It also makes Japan the fifth nation in history to complete a soft lunar touchdown.

The elation of seeing SLIM perform a controlled landing on the moon was short-lived, however. Joy turned to concern as they watched the power levels drain away.

Instead of allowing the power system to drain completely, the team made the decision to put the lander to sleep. Essentially, they put the craft in standby mode.

“The battery was disconnected according to our procedures with 12% power remaining, in order to avoid a situation where the restart (of the lander) would be hampered..

“… As a result, the spacecraft was switched off at 02:57 (Saturday, Japan time, or 17:57 GMT, Friday).”
JAXA

Fortunately, and much to their relief, mission control successfully gathered details of Slim’s predicament before they initiated the shutdown. They also retrieved images and data about its descent to the lunar surface.

Agencies usually attempt a lunar landing during the day (on the moon), and this is when the sun rises in the East. This gives the lander around two weeks (in our time) sun on the moon. After this, the sun sets in the west and gives the moon two weeks of darkness.

At the moment, SLIM is basking in sunlight on the slopes of Shioli Crater. If the team at JAXA are correct, and the lander’s panels are pointing west, then they need to wait until “lunar afternoon”. The sun will then hopefully be far enough west to illuminate the panels and start charging the batteries.

SLIM has two small rovers that it carried to the moon, and available data suggests they successfully ejected as planned – just before touchdown.

Japan’s moon lander also has an infrared camera. With this camera, they will study the geography of the immediate surroundings. It is not known yet just how much it will be able to ‘investigate’ if power levels are restored.