Japan says Konnichiwa to Moon: Slim spacecraft lands, but not all went well

After brief speculation over its fate, the Japanese space agency, Jaxa, confirmed that its ambitious Smart Lander for Investigating Moon (SLIM) landed on the Moon.

However, there was a hitch during the landing attempt and the spacecraft is yet to receive solar power as the solar cells on the mission are not working. The spacecraft is currently powered on battery life, which last for just a few hours.

The Japanese space agency said that if solar cells are not restored, the mission will still be called successful since it demonstrated a high-precision landing on the Moon. “We have been more or less been able to achieve the landing,” said officials.

The landing makes Japan the fifth country to touch the lunar surface after India, which landed Chandrayaan-3 on the Moon in 2023.

The precision landing technology of SLIM, also referred to as the “Moon Sniper,” represents a significant advancement in lunar exploration. Unlike previous missions that targeted broad landing zones, SLIM was designed to land within a mere 100 meters (328 feet) of its intended target. This level of accuracy is unprecedented for a robotic probe, especially one that is low-cost and lightweight.

“Slim has targeted a high precision landing with an accuracy of 100 meters, but we need to analyse data to confirm it,” senior officials of the Japanese space agency said in a press conference.

The space agency said that they will be analysing the data in the coming days to understand what happened with the spacecraft following the landing approach commenced. They said that at this point, the battery power is expected to last just a few hours post-landing.

Equipped with vision-based navigation technology, SLIM autonomously adjusted its trajectory during descent by matching preloaded images from Japan’s Kaguya lunar orbiter with real-time photographs of the moon’s surface. This allowed the lander to pinpoint its location and navigate to the precise landing site, a process managed by specialized image processing algorithms developed by Jaxa.

The landing site near Shioli crater was selected for its scientific potential. Data suggests the presence of olivine, a mineral that could provide insights into the Moon’s mantle and contribute to our understanding of lunar formation and evolution.

SLIM also carried unconventional rovers, including the hopping Lunar Excursion Vehicle 1 (LEV-1) and the baseball-sized LEV-2, developed in collaboration with Tomy, Sony, and Doshisha University. These rovers are equipped to traverse the challenging lunar terrain and conduct scientific investigations.

The space agency confirmed that the mini probes separated from the spacecraft during the descent and are transmitting to Earth. The team is planning to get the pictures captured by the LEV-1 in the coming days.

A lot was riding on the success of the Slim mission. The technology developed through Slim will be a crucial step for JAXA’s upcoming Martian Moon eXploration (MMX) mission, which aims to collect samples from Phobos.

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.