Japan has become the fifth nation in history to successfully land a spacecraft on the lunar surface following the smooth descent of its small SLIM lander on Monday. However, initial euphoria has given way to uncertainty after officials revealed solar panels on the craft are unable to generate power.

The Japan Aerospace Exploration Agency (JAXA) confirmed during a press conference two hours after the meticulously executed 20-minute landing maneuver that SLIM had touched down intact. But the agency could not clarify why the lander's batteries cannot recharge to enable full functionality and science operations.

SLIM joins an elite club of past moon landers like the Soviet Union's Luna 9 in 1966, NASA's Surveyor 1 the same year followed by China's Chang'e-3 mission in 2013 and India's Chandrayaan-3 last year.

While telemetry data continues streaming from the dormant SLIM showing it survived the complex landing, JAXA said it could take several days to fully diagnose the craft's energy generation issue. The most likely culprit is suboptimal orientation preventing adequate sunlight from reaching its solar arrays.

By scheduling a second briefing next week, JAXA buying more time to strategize recovery plans if adjusting SLIM's angle to capture more light is indeed the problem. Controllers may also put the lander in a switched-off preserved state until sunlight conditions change naturally in the coming days.

SLIM did successfully deploy two tiny LEV rover payloads in the final stretch of its descent to the surface. So JAXA can confirm that key part of the mission worked before the unexpected energy shortage.

While the setback casts uncertainty over SLIM's two-week surface operations window, Japan has still staked its claim in elite lunar exploration company. This inaugural moon landing still represents a pivotal technological achievement and learning opportunity for JAXA.

Analysis of SLIM's telemetry and performance will enable improvements to systems critical for potential follow-up moon missions. So once the root cause is fully diagnosed, researchers can feed vital data back into development cycles for future spacecraft and landing mechanisms.

So although hopes were high for SLIM to claim the title of first fully successful Asian moon lander, JAXA sees immense value in advancing Japan's capacity for complex deep space operations despite the lingering battery questions.