Japan has become the fifth country to land a craft on the moon, but problems with its solar panels mean the mission hangs in the balance.
Dubbed the “moon sniper”, the Smart Lander for Investigating Moon (SLIM) probe was attempting a risky landing on a slope at the rim of a crater using “precision” technology.
While the craft landed at about 3.20pm UK time and can communicate with the team on Earth, it cannot generate its own energy – potentially because its solar panels are angled incorrectly.
It means SLIM is relying on its own battery – with 74% charge at the time of landing – and could only have a few hours left.
The Japan Aerospace Exploration Agency (JAXA) hopes a shift in the sunlight’s angle will hit the panels in a way that can restore its functions.
“It takes 30 days for the solar angle to change on the moon,” Hitoshi Kuninaka, the head of JAXA’s research centre, told reporters after the landing.
“So, when the solar direction changes, and the light shines from a different direction, the light could end up hitting the solar cell.”
Most moon landings – which had only been achieved by the United States, Russia, China and India – aim for a spot within an accuracy of several kilometres.
But SLIM tried to land within 100m of its target, which Mr Kuninaka said was “most certainly achieved”, according to trace data, though its specific location won’t be known for a month.
SLIM’s heater has been turned off as the team tries to conserve power and Mr Kuninaka said they want to keep the “status quo” for the moment while they wait for more accurate information.
How did it land?
As the probe descended onto the surface, it was designed to recognise where it was flying by matching its camera’s images with existing satellite photos of the moon.
This “vision-based navigation” is what gives it the ability for a precise touchdown, JAXA has said.
Shock absorbers make contact with the lunar surface in a “two-step landing” method, with the rear parts touching the ground first, followed by the entire body gently collapsing forward and stabilising.
On landing, JAXA said SLIM deployed two mini-probes – a hopping vehicle as big as a microwave oven and a tennis ball-sized wheeled rover – that would have taken pictures of the spacecraft.
SLIM was launched in September and has taken a fuel-efficient four-month journey to the moon.
