Japan's Slim probe lands on moon, but can't generate solar power

TOKYO — Japan on Jan 20 became the fifth country to put a spacecraft on the moon, but solar power issues threatened to cut short the nation's mission to prove a "precision" landing technology and revitalise a space programme that has suffered setbacks.

The Japan Aerospace Exploration Agency (Jaxa) said its Smart Lander for Investigating Moon (Slim) landed the moon's surface at around 12.20am (11.20pm on Jan 19, Singapore time) but its solar panels were not able to generate electricity, possibly because they are angled wrong.

Jaxa prioritised the transfer of Slim's data to earth as the probe relied only on its battery, which would last for "a few hours" despite "life-sustaining treatments" such as turning off its heater, Hitoshi Kuninaka, the head of Jaxa's research centre, told a press conference.

Jaxa will maintain the status quo rather than take risky actions and hopes a shift in the sunlight's angle will hit the panels in a way that can restore its functions, he added.

"It takes 30 days for the solar angle to change on the moon," Dr Kuninaka said. "So, when the solar direction changes, and the light shines from a different direction, the light could end up hitting the solar cell."

Signal from the Slim was lost, data from Nasa's Deep Space Network showed. It was not immediately clear whether the signal loss was temporary or a power-saving measure.

Dubbed the "moon sniper", Slim attempted to land within 100m of its target, versus the conventional accuracy of several kilometres, a technology Jaxa says will become a powerful tool in future exploration of hilly moon poles seen as a potential source of oxygen, fuel and water.

"Looking at the trace data, Slim most certainly achieved a landing with 100m accuracy," Dr Kuninaka