Japan starts precision landing of 'moon sniper' SLIM spacecraft

By Kantaro Komiya

TOKYO (Reuters) - Japan started a "precision" landing attempt of its moon probe on Saturday, its bid to become the world's fifth country to achieve a moonshot and revitalise a space programme that has suffered a wave of recent setbacks.

The Japan Aerospace Exploration Agency (JAXA) said the Smart Lander for Investigating Moon (SLIM) has begun an autonomous 20-minute descent from 15 km (9 miles) above the moon's surface.

Dubbed the "moon sniper", SLIM attempts to land within 100 metres (328 feet) of its target, versus the conventional accuracy of several kilometres.

JAXA says this landing technology will become a powerful tool in future exploration of hilly moon poles seen as a potential source of oxygen, fuel and water - factors necessary to sustain life. It will take up to a month to verify whether SLIM had achieved the high-precision goals, JAXA has said.

Japan is increasingly looking to play a bigger role in space, partnering with ally the United States to counter China. Japan is also home to several private-sector space startups and the JAXA aims to send an astronaut to the moon as part of NASA's Artemis program in the next few years.

But the Japanese space agency has recently faced multiple setbacks in rocket development, including the launch failure in March of its new flagship rocket H3 that was meant to match cost-competitiveness against commercial rocket providers like SpaceX.

The failure caused widespread delays in Japan's space missions, including SLIM and a joint lunar exploration with India, which in August made a historic touchdown on the moon's south pole with its Chandrayaan-3 probe.

JAXA has twice landed on small asteroids, but unlike with an asteroid landing, the moon's gravity means the lander cannot pull up for another try, its scientists said. Three lunar missions by Japanese startup ispace, Russia's space agency and American company Astrobotic have failed in the past year.

Only four nations - the former Soviet Union, the United States, China and India - and no private company have achieved a soft landing on the moon's surface.

SLIM's successful touchdown and demonstration of the precision landing "will help Japan to keep its technology advanced at a very high level in the world," Ritsumeikan University professor Kazuto Saiki has said before the touchdown attempt. Saiki developed SLIM's near-infrared camera that will analyse moon rocks after the touchdown.

The 2.4m by 1.7m by 2.7m vehicle includes two main engines with 12 thrusters, surrounded by solar cells, antennas, radar and cameras. Keeping it lightweight was another objective of the project, as Japan aims to carry out more frequent missions in the future by reducing launch costs. SLIM weighs 700 kg (1,540 lb) at launch, less than half of India's Chandrayaan-3.

As the probe descends onto the surface, it recognises where it is flying by matching its camera's images with existing satellite photos of the moon. This "vision-based navigation" enables a precise touchdown, JAXA says.

Shock absorbers make contact with the lunar surface in what JAXA calls new "two-step landing" method - the rear parts touch the ground first, then the entire body gently collapses forward and stabilizes.

The precision landing "won't be a game changer", but the cost-reduction effects of it and the lightweight probe manufacturing might open up moonshots to space organisations worldwide, said Bleddyn Bowen, a University of Leicester associate professor specialising in space policy.

"Not as big as the United States or the Soviet Union of old or China today in terms of scale, but in terms of capability and niche advanced technologies, Japan has always been there."

On landing, SLIM also deploys two mini-probes - a hopping vehicle as big as a microwave oven and a baseball-sized wheeled rover - that will take pictures of the spacecraft. Tech giant Sony Group, toymaker Tomy and several Japanese universities jointly developed the robots.

SLIM was launched on Japan’s flagship H-IIA rocket in September and has taken a fuel-efficient four-month journey to the moon.

(This story has been refiled to fix the day to 'Saturday' from 'Thursday' in paragraph 1)

(Reporting by Kantaro Komiya; editing by Miral Fahmy and Nick Zieminski)