Moon: Japan tries to be the 5th country to land on the natural satellite – 01/17/2024 – Science

Continuing the intense season of unmanned lunar missions, it is time for Jaxa (Japanese space agency) to attempt a soft landing on the Moon. If successful, Japan will be the fifth country to accomplish the feat, after Russia (then part of the former Soviet Union), USA, China and India.

The Slim probe (acronym for Smart Lander for Investigating Moon) represents the first Japanese state attempt to conduct a landing, years after the successful orbital lunar mapping mission with the Selene spacecraft (also called Kaguya), which operated between 2007 and 2009.

It is not, however, the first attempt by the Japanese to land an artifact on the Moon. Last year, the Japanese company ispace failed in its attempt to reach the lunar surface with its Hakuto-R module, leading to a line of private missions that would continue with the launch of the Peregrine module, a spacecraft from the American company Astrobotic, on January 8 of this year.

The module had a problem with its propulsion system, with a tank rupture and propellant leaking, which condemned the mission. Unable to land on the Moon, and to avoid creating space debris in cislunar space, Astrobotic decided to leave the spacecraft on a trajectory that will bring it back to Earth, where it will burn in the atmosphere, this Thursday (18).

Jaxa hopes to have better luck with Slim, not only demonstrating the ability to descend to the surface, but doing so with a level of precision never achieved before. There have even been landings with very reasonable precision in the past – such as the exemplary Apollo 12, which landed less than 200 meters from the Surveyor 3 probe, then piloted by a human, Pete Conrad, in November 1969.

Slim wants to take this to a new level by landing less than 100 meters from a designated target. “Precision landing is a mandatory technology for the next generation of lunar exploration,” says Shin-ichiro Sakai, Slim project manager at Jaxa.

Precision landing technology will be essential for reaching difficult-to-access locations where there is great scientific interest or where natural resources such as water ice can be exploited. The Japanese hope to demonstrate it in a light, unmanned vehicle with a relatively modest cost – it is estimated that the Japanese agency spent around US$120 million on the mission.

Weighing a modest 590 kg, Slim was launched into space on September 6, 2023, by an H-IIA rocket, from the Tanegashima Space Center. Taking a low-energy route to the Moon, the probe entered orbit of the natural satellite on December 25 and, so far, has worked as expected.

Last Sunday (14), the spacecraft completed the maneuver to circularize its orbit, stabilizing itself around 600 km from the lunar surface. From then on, the probe will maneuver to gradually reduce the perilunium (point of maximum approach to the Moon) until it reaches a mere 15 km from the surface. From there, around noon this Friday (19), the spacecraft will begin its descent procedure to the Shioli crater (near the lunar equator), which should be completed in around 20 minutes.

The landing module will adopt a strategy never used before, in which the descent takes place vertically and only after touching the rear legs on the ground will the vehicle settle horizontally. If this maneuver is successful, Slim should release two small rovers, one of them a copy of the one that flew on Hakuto-R, in its failed landing attempt, last year.

With this, Jaxa hopes to be on par with Isro (Indian space agency), which enchanted the world with its first lunar landing, on August 23 last year, with the Chandrayaan-3 mission. But this certainly won’t be the last landing attempt this year.

The American company Intuitive Machines intends to make its first attempt in February, and China is preparing its Chang’e-6 mission for May, destined to be the first to collect samples from the far side of the Moon. Astrobotic had a second launch scheduled for the end of this year, but with the Peregrine failure, it is unclear whether the original schedule will be maintained.