At 8:51 yesterday, December 25 (Spanish peninsular time), the Japanese space agency JAXA officially announced that the SLIM mission, which had left Earth in September, had successfully entered the Moon's orbit and that the ship was “in normal condition.”
Over the next few days, the engineers responsible for the mission will adjust SLIM's trajectory on several occasions in preparation for the final landing maneuver, scheduled for 4:20 p.m. on the 19th of this month of January. This operation will be carried out with a precision never seen before so that the spacecraft manages to touch the lunar soil with a maximum deviation of 100 meters from the planned objective, on the edge of the Shioli crater, a place where rocks from the lunar mantle would be found and of great scientific interest.
If successful, Japan will become the fifth country to land on the Moon, after the United States, the former Soviet Union, China and India.
According to the data provided by JAXA, SLIM's entry into orbit of the Moon has been carried out with a very elongated polar elliptical trajectory that, at its lowest point (called perilunium), reaches up to 600 kilometers in height and rises up to the 1,200 kilometers at its apolunio or furthest point.
From now on, and over the next few days, the spacecraft's path will be adjusted to reach a circular orbit of 600 km high, which will be corrected again until it enters a new ellipse that will place SLIM only 15 km above the surface. of the Moon in its perilun and with a speed of 1,700 meters per second. This will be the position from which the final descent maneuver is attempted.
The spacecraft will use an autonomous navigation system, which will compare the view during descent with the set of maps that a previous Japanese mission, called Selene, captured in 2007. Throughout the maneuver, an onboard radar will constantly monitor SLIM's altitude. , and in the last meters a laser device will allow obtaining high-precision height readings and making the necessary automatic adjustments.
The objective is to achieve a landing no more than 100 meters away from the planned location, on the edge of the Shioli crater. This level of precision is unprecedented in lunar operations, and to achieve it the Japanese space agency has developed special algorithms to process with great speed and accuracy the image bank that will be used as a guide.
If all goes well, SLIM will land on the moon with the help of devices capable of absorbing most of the impact against the surface. In addition, the maneuver faces the challenge of landing in a place that is inclined by about 15 degrees.
The place chosen for the descent of SLIM is an impact crater of about 270 meters in diameter located in mid-latitudes, in the southeast of the visible side of the Moon. The choice of this objective has been based on data collected by the Selene mission, which suggests that exposed minerals from the lunar mantle would be found on the edges of Shioli. Therefore, these would be very interesting materials, from a scientific point of view, to analyze the formation and subsequent evolution of our satellite.
Consequently, the high precision with which the lunar landing is intended is justified by the need, for the success of the mission, to be able to touch the ground as close as possible to the exposed materials.
To carry out the planned studies, SLIM is equipped with a camera capable of observing objects located up to 30 meters away, and which will use various filters to analyze how the exposed rocks reflect sunlight and thus know their composition.
The Japanese mission must be able to complete the analyzes within a lunar daytime period (equivalent to about two Earth weeks), since the spacecraft's electronics are not prepared to survive the low temperatures of the long night on the Moon ( that go down to -130C).
SLIM will also deploy two small robots on the lunar surface, with an unconventional design. On the one hand, the so-called LEV-1 (an acronym in English that means lunar excursion vehicle 1) will move by jumping. It is equipped with cameras and devices to measure the temperature, radiation and inclination of the ground, and has the capacity for direct communication with the Earth.
On the other hand, the spherical and small LEV-2 (the size of a tennis ball) will open into two halves, once it touches the lunar surface, to use them as wheels. Toy specialist companies such as Tomy and Sony have collaborated in its design. Communications with our planet will be carried out through its companion, LEV-1.
In recent months, there has been growing interest in lunar exploration, both by the main government space agencies and also by private companies.
Last August, India, with its Chandrayaan-3, became the fourth country to successfully land on the Moon and the first to do so near the south pole, and it achieved this after, a couple of days before, The Russian Luna-25 mission failed in this same attempt.
In April, the Japanese spacecraft Hakuto-R could have become the first privately funded mission to land on our satellite, but an error in the autonomous descent operation caused it to run out of fuel in the last moments and crash.
But without a doubt, the great lunar projects are those planned by the United States and China. With the Artemis space program, NASA plans a human return to the Moon, surely around the year 2027 (it will be the Artemis 3 mission). The chosen location is close to the south pole, a region of strategic interest due to the presence of water ice in some of its deepest craters.
For its part, the Asian giant announced that its astronauts could set foot on the Moon around 2030 but without giving more details. The powerful Chinese space program has had a robot on the far side of the Moon since 2019, and its Chang'e 5 mission managed to bring samples of lunar rocks to Earth at the end of 2020, an event that had not happened since 1976. .
