Japan is next to launch spacecraft for lunar landing – 08/24/2023 – Science

The Indians had not even finished celebrating the landing of Chandrayaan-3 on the Moon, and the world was already preparing to follow another unmanned journey to the surface of the natural satellite: this Friday (25th), Japan should launch the Slim mission, which could make the country the fifth to achieve such a feat, right after India.

Takeoff is scheduled for 21:34 on Friday (Brasília time), which is equivalent to 9:34 on Saturday by Japanese time zone. It will fly along with an astrophysical X-ray satellite aboard a Mitsubishi Heavy Industries H-IIA rocket from the Tanegashima Space Center in Japan.

It will, in fact, be the second chance for the country to carry out a successful landing. The first was conducted by a Japanese company, ispace, with a lander called Hakuto-R. Launched in December last year, the modest vehicle successfully carried out all stages of the flight to the Moon, going there on a low-energy trajectory, which consumed months in space. However, in the last few seconds before consummating the landing, in April of this year, a conflict between the sensors and the on-board computer led to the fuel running out before the probe touched the ground, and it crashed to the ground at high speed. Otherwise, Japan would be the fourth country to land on the moon, not India.

Now, the mission is conducted not by a company, but by the Japanese space agency itself, Jaxa. Slim is an acronym for Smart Lander for Investigating Moon, or Lander Intelligent for Investigating the Moon. The word also plays with the term “slim”, thin in English, since it is a small mission: 590 kg in all, of which two thirds are fuel.

The acronym gives a good clue as to its main purpose: testing automated techniques for performing a high-precision landing on the lunar surface. It is interesting to note that all these landings to date, whether on the Moon, Mars or any other celestial body, have low accuracy. That is, managers can choose the approximate landing region, which has the shape of an ellipse drawn on the ground, but the exact location where the vehicle will land depends on factors beyond their control.

For example, the designated landing area for Apollo 11, the first manned landing in 1969, was an ellipse measuring 20 km by 5 km. Apollo 12 made an impressive display of precision as it was piloted by an astronaut to descend just 163 meters from the unmanned Surveyor 3 probe, launched years earlier by the United States.

Slim intends to improve this number even further, with a much smaller vehicle and without relying on a pilot on board. Its expected precision is one hundred meters, which would make it possible to explore more challenging and scientifically interesting locations, without having to worry so much about nearby geographic features that could endanger the mission. The plan is for it to land inside the Shioli crater, in Mare Nectaris, close to the lunar equator, on the side that always remains facing Earth. This, however, will take time.

Taking a low-energy trajectory (like ispace’s Hakuto-R mission), the probe should only enter lunar orbit three to four months after launch, and then spend between two and four weeks circling the moon before starting. the landing procedure. It will be between the end of this year and the beginning of the next.

It is, however, yet another sign of the new enthusiasm that has gripped lunar mission planning. NASA, the American space agency, is already projecting a manned return to the Moon with the Artemis program. The first orbital flight with astronauts should take place at the end of next year. The first manned landing is officially scheduled for the end of 2025, but it will most likely escape to 2026 or 2027 – the main obstacle is the development of the Starship, a vehicle created by SpaceX and selected by the agency for the landing.

The Chinese, in turn, work more discreetly, but already promise a manned lunar landing by the end of this decade. In addition, the country maintains a partnership with Russia for the development of a research station on the natural satellite, initially composed of unmanned missions – the first of which would have been the Russian Luna-25, had it not failed last Saturday (19 ) on landing.

South Koreans also launched their first orbital mission to the Moon last year, and several companies from several countries, especially the US, intend to carry out flights and landings on the lunar soil, in what seems to be a significant change in the paradigm of exploration. Japan’s Slim is next in line, but it’s far from the last Moon mission to launch in the coming months and years.