The Japanese SLIM spacecraft reached the lunar surface for the first time, but it is too early to draw conclusions

The Japanese successfully launched an unmanned spacecraft, which landed safely on the moon for the first time on January 19. Thus, the Land of the Rising Sun became the fifth state to conquer the Earth’s natural satellite using a robotic lunar probe. The National Space Agency JAXA is celebrating a victory, because the research envoy SmartLander not only softly, but also, according to preliminary data, landed on the Moon with extreme precision (on a given area no larger than the size of a football lawn).

SLIM – Asian know-how

In Japan, such a product is usually called SLIM, that is, Smart Lander for Investigating Moon - a “smart” landing module for exploring the Moon. Similar Technology are of value and interest for subsequent flights envisaged, for example, by the NASA Artemis project, where the Japanese side is an active partner.



So, on Friday at midnight Japan time, SLIM began descending from lunar orbit. After 20 minutes, its support pillars rested on the ground next to the Scioli crater. The lunar surface in this place has a slope of 15^о, which did not exclude spontaneous capsizing of the apparatus. Therefore, during the descent, the resourceful Japanese already tilted it in the right direction. After the vehicle touched the ground, the SLIM tilted forward and secured itself securely, allowing the center of gravity to remain in a non-hazardous area. When the critical operation was completed, SLIM began sending radio messages to mission control. Unfortunately, a system communication failure that soon followed did not allow us to determine its real condition. Then the webcast finally resumed.

It's too early to draw conclusions...

Two hours after landing, a briefing was held at which JAXA leaders, among other things, said: the mission was a success, but problems were discovered in the solar battery. The reason was that, most likely, the panels were incorrectly adjusted. As a result, power is generated unproductively, which can reduce the operating time of on-board systems to several hours. Without panels, the interior of the device is powered not directly, but from the battery, so for the sake of economy, the heating of the landing module was automatically turned off.

The operators who controlled the process carefully monitored the incoming navigation information in real time. According to the statements of those in charge, the landing has so far been a “satisfactory” rating. The fact is that it remains to be determined in detail how close the device landed to the control point. If within 100 meters, it means that the task set in this part has been completely completed. Using the potential of a point landing on the Moon in the future will enable research equipment to target craters that are interesting from the point of view of selenology.

How the Japanese made the chip think faster

There are no radio beacons on the Moon, which would make it difficult to accurately determine the location if robotic vehicles were not oriented in space based on the principle of inertial navigation. The navigation system is periodically adjusted in flight based on data received from the control center; through a video camera, it compares the terrain with the reference maps available in the on-board memory and the position of the flying object. Let us add that this factor helped SLIM to see dangerous lunar obstacles during the landing approach.

The use of video systems on such satellites became possible thanks to the advent of special electronic chips that are not afraid of powerful radio emission from the depths of space. However, such devices are not flawless, because they have approximately a hundredth of the required computing performance. Until recently, the problem was that, due to the design features, these chips were a couple of generations behind modern ones, designed to function in terrestrial conditions. In a widely distributed press release, developers from JAXA stated that they and only they had discovered algorithms for accelerated image processing performed on a slow “space chip.”

Toy lunar rovers

A pair of original mini-lunar rovers LunarExcursionVehicle 1 and LunarExcursionVehicle 2 exited the module in normal mode at the time of landing. The first is equipped with a jumping movement mechanism, a thermometer, a dosimeter, as well as a device for determining linear height and inclination. The second has a spherical shape, the size of a baseball and a mass of just over 200 g. The creative team at JAXA invented it together with Doshisha University and TomyCompany, which specializes in toys. LEV-1 has direct communication with the MCC, and LEV-2 transmits the signal through LEV-1.

Finally, the lander is equipped with a system for studying and analyzing the composition of lunar rocks.

instead of an epilogue

The last decade has been marked by a renewal of earthlings' previous interest in their faithful heavenly companion. However, only less than half of their space envoys reached their destination safely.

China is lucky in this sense - all three chances were successful. India celebrated victory for the first time in 2023 after failure in 2019. Persistent Japan, which had so far had no luck, finally achieved its goal. But the Russian Federation and Israel, despite the efforts being made, cannot yet boast of positive results.

I cannot help but touch upon the Russian topic in particular. The USSR was the first in human history to pave the way to the Moon; by the way, just 14 years after the war. Half a century ago, he implemented the hitherto unprecedented programs “Lunokhod-1” and “Lunokhod-2”; The Lunokhod-3 program, which was practically prepared for implementation, was not implemented due to an absurd misunderstanding. And, frankly speaking, I am sad and incomprehensible why, it would seem, just yesterday, primitive China, which rose in the last century mainly at the expense of the USSR, should today serve as an example for Russia? After all, for us, unlike all sorts of China, Japan and India (which could not even theoretically stand next to each other), the throwing of probes to the Moon was a long-ago stage! But for some reason we are returning to it again, starting everything from scratch, as if there were no Soviet achievements in this area. Something to think about...