On September 14, 1959, 65 years ago, the automatic interplanetary station Luna-2 crashed into a natural satellite of the Earth. This device became the first man-made object launched from our planet and reached the surface of another celestial body. The scientific director of the Space Research Institute (IKI) of the Russian Academy of Sciences, the scientific director of the first stage of the lunar program (research by automatic stations), spoke about the scientific value of the first lunar missions, various approaches to the study of the natural satellite of the Earth, as well as the current state of the Russian lunar program in an interview with TASS academician Lev Zeleny.
— Tell us, what is the value of the Luna-2 mission? What did she help to find out?
— The history of Luna-2 began nine months earlier, when on January 2, 1959, Luna-1 was launched, which was supposed to crash into the Moon, deliver a pennant — in general, everything that Luna-2 did. But the device missed. Boris Yevseevich Chertok (S.P. Korolev's right-hand man) This is how it describes the reason:
"The reliability of hitting the Moon, among other things, depended on the accuracy of turning off the engines of the second stage and launching the third stage. Possible errors of the autonomous system of switching off the second-stage engines from the longitudinal acceleration integrator exceeded the permissible ones. Therefore, from the very beginning <...> we decided to use a radio control system to turn off the engine based on speed and coordinate measurements. But the radio team was too late! Then, of course, they figured out that the ground radio control points were to blame..."
As a result, the device flew past at a distance of about 6 thousand km. But, unfortunately, B.I. Chertok does not write that this "seemingly unsuccessful" Luna-1 made a great discovery due to the fact that it had ion traps made by the future ICI employee Konstantin Iosifovich Gringauz.
It was assumed that the space between the Earth and the Moon was empty, almost a vacuum. And ion traps have recorded in this space quite strong streams of hot plasma moving from the Sun. This is what later became known as the solar wind — it was a real experimental discovery. Theoretically, this was predicted by the recently deceased great American scientist Eugene Parker — at first no one believed him, his article was not published, and in fact the first experimental confirmation of this very important physical phenomenon was the fruits of the work of Konstantin Gringause.
Why I focus so much on the solar wind is what creates space weather on Earth. There were similar instruments on Luna-2, and they naturally confirmed the existence of the solar wind, but for the first time this was done on Luna-1 nine months earlier.
In addition to this discovery, another very important experiment was conducted under the leadership of Joseph Samuilovich Shklovsky — the so-called artificial comet. To visually prove that the device is really flying to the Moon, a kilogram of sodium was sprayed on it. It turned out to be an orange cloud that could be observed through a telescope. It was the first such experiment in history — an artificial comet.
Luna-2 had great difficulties at the time — the flight was postponed many times due to carrier malfunctions, but still on September 12 it flew away. On September 14, the station flew to the Moon, crashed into it at a speed of about 3.3 km/s, created a small crater and scattered pennants with the coat of arms of the USSR and the inscription "USSR" on the surface of the Moon. It was a great source of pride for Nikita Sergeevich Khrushchev — he, as you know, presented such a pennant to President Dwight Eisenhower during his trip to the United States.
The scientific measurements of Luna-2 were not very significant compared to Luna-1. The magnetic field of the Moon was also measured, but due to the fact that the lifetime of the device was short, there were no large number of scientific results, but there was a huge political significance - the first object in the history of mankind created on Earth touched another celestial body. This never happened, and the Soviet Union did it first.
I must say that later the first spacecraft to land gently on the moon was also the Soviet Luna-9 spacecraft. This happened seven years later, in February 1966, two weeks after the death of Sergei Pavlovich Korolev, who designed these first "Moons". The next devices were designed by another organization, where Korolev transferred this topic, now the Lavochkin NGO. Georgy Nikolaevich Babakin became the chief designer of these new "Moons".
— Neither the first nor the second "Moon" had a propulsion system?
— Yes, they were flying in ballistic mode. At this stage, the main thing was to get there. Then the propulsion system appeared.
— Are projects of penetrator devices being discussed today, which, when landing, extinguish excess kinetic energy due to penetration into the ground?
— The penetrators actually turned out to be a very sad story, which, in general, did not end with anything.
Since the beginning of the noughties, there has been a Luna-Globus project in Russia. He was engaged in the Institute of Geochemistry and Analytical Chemistry named after V.I. Vernadsky, aka GEOHY. Indeed, the idea of creating a global — hence the word "Globe" — network of penetrators that will crash into the moon was proposed. With such an impact, the device slows down with a huge acceleration, several hundred g. The devices themselves had to have seismometers capable of surviving such overloads. It was assumed that after the seismometers were embedded in the ground, they would transmit data on the seismic vibrations of the Moon from its various regions. We will get such a seismic tomography — a very modern and very good way that would help to estimate the size of the Moon's core and finally understand the models of the formation of our satellite.
The idea was reasonable, but it turned out that such equipment, resistant to extreme overloads, was easy to offer, but impossible — at least at that time — to make. Such systems were indeed developed in the Soviet Union, during the preparation of the Martian projects. Then, after the collapse of the USSR, the opportunity to create such equipment in Russia disappeared, they tried to order it in Japan, in England… But no country was able to create such penetrators then, the scientific equipment of which can survive a collision with the surface. This concept—at least for the time being—proved unsuccessful. Probably, in principle, the idea has the right to exist, but the technology of that time did not allow it.
The Luna-Globus project was in crisis, and somewhere around the turn of the 2010s, when the first reliable data on the presence of water ice in the circumpolar regions of the Moon appeared, we reformatted the program. Luna-Globus became known as Luna-25, and our entire lunar program was reoriented to study the poles of the Moon. These poles have such unique properties, very different from the mid-latitude Moon, which was explored by Soviet and American expeditions in the 1970s and 1980s.
This is how the modern stage of lunar exploration began. We in Russia were the first to formulate this clear program for exploring the poles, but we were not the first to implement it.
In August last year, an Indian spacecraft landed in the area that we also considered a priority object of the South Pole. And he sat down very well, gave very good results. The Indian colleagues also managed to do this not the first time: a few years earlier, the landing vehicle of their Chandrayan-2 expedition crashed. Still, to paraphrase Pushkin, only "experience, the son of difficult mistakes," prepares for us "wonderful discoveries.".. This, of course, also applies to our difficult but important experience gained during the unsuccessful landing of Luna 25 in the same August 2023.
In the short time since then, already in 2024, several automatic vehicles landed in this southern polar region, to varying degrees successfully — both Japanese and commercial American vehicles, and a Chinese expedition is also preparing there. Chinese scientists have very good experience of soft landings, including on the far side of the Moon, and the delivery of lunar soil to Earth.
Unfortunately, we have lost our leadership in the exploration of the circumpolar Moon, but not only victory is important here, but also participation. We remain somewhat optimistic, despite the death of Luna 25. The Luna-26 orbiter and Luna-27 landers are currently being prepared.
— Last year, you told us that the IKI proposed to Roscosmos to launch two Moons-27. Has the state corporation already accepted this offer?
— The state Corporation supports this proposal, but unfortunately, it also does not print money, so there is no final decision. Let me remind you that the creation of a second device means an increase in costs not by half, but by only 30-35 percent — you can test two identical devices on the same equipment.
Here I see such a very attractive opportunity, and there are many arguments in support of this new idea that if it does not work out to create two devices, then send the only device not to the South Pole, which will be sufficiently explored by that time, but to the North — no one is going there yet. I emphasize that this is only for now. I am sure that this idea, like all other good ideas, will soon be picked up by someone, while, as usual, everything is harnessed for a long time — but now, unfortunately, we do not drive fast.
— So if in the end it is decided to launch only one device, then the academy will insist on sending it to the North Pole?
— The Academy will offer. Today, the situation changes every month, because new plantings give new results. This is a very dynamic situation, since humanity has begun to explore the truly polar regions of the Moon only now, the first soft landing took place a little over a year ago - on August 23, 2023. Right on my birthday, but it was not a Russian device, but an Indian one. And during this time, he gave a lot of scientific results, allowed us to take a fresh look at the temperature regime in these areas, at the composition of the regolith. These data still need to be processed and comprehended.
Some discoveries that may occur between the first landing in 2023 and the planned landing of our spacecraft in five to six years (we can already see that it will not be possible to do this before 2028-2029) can undoubtedly affect our plans. The device, which is being made for the South Pole, can also land on the North Pole — the ballistic flight patterns there are almost identical. But during this time, the device (or devices) must be done in time and, closer to the launch date, finally decide where to fly. We have already worked out the landing sites and selected them in both regions.
— Luna-26 will help with a more specific choice of landing sites, right?
— Luna-26, of course, will also help you figure out how to make high-precision maps of the surface. In general, there are a lot of interesting things on the Moon — there are tasks related to both gravitational anomalies and magnetic anomalies, and all this, including the processes of interaction of the Moon with the solar wind, will be studied in detail on the Luna-26 orbiter.
At the second stage (the first in the 1960s and 1970s was Soviet-American), many countries joined the study of the Moon — we get to know the Moon much deeper. Not only mid-latitude, but also polar.
I mentioned earlier that so far there is not even a universally accepted model of his education. The reason why GEOCHIAN scientists insisted so much on a lunar expedition with penetrators is that, based on the size of the Moon's core, conclusions can be drawn about the mechanisms of its formation.
Now there is a model of the so-called mega-impact, according to which the Moon was formed as a result of the collision of the young Earth with some large celestial body, about the size of Mars, and from this melt arose a renewed Earth, and very close to it the Moon. Gradually, she cooled down, moved further and further away — she is still moving away. And therefore, in their composition, the outer layers of the Moon are very similar to those on Earth.
But there are also factors that contradict this model. This is a very "live" problem, scientists are still arguing. Colleagues from the Vernadsky Institute are of the opinion that there was no mega-impact, and the Moon and Earth were formed from a protoplanetary cloud in the same way as the older and younger brothers. There are facts that this theory explains well, and there are those that it cannot explain. Therefore, I am an adherent of the first theory, although I understand some of its shortcomings.
— In May, the government announced that the list of improvements that the next Russian lunar stations will undergo in order not to repeat the fate of Luna-25 will be determined in September. Has this list already been formed? What kind of improvements are envisaged in it?
— There are a lot of technical improvements, it will probably be boring to talk about it.
Luna-25 was a good, reliable device, but the protection that fended off the occurrence of such situations turned out to be insufficient. On Luna-27, of course, much more thorough ground testing will be carried out. Special attention will be paid to the development of soft landing systems at the very last stages of approaching the Moon. It is worth remembering that in Soviet times, for reliability, all devices were made in pairs: lunar, Martian, and Venusian. This simplified the testing and increased reliability. As I said above, such duplication not only increases reliability, but also qualitatively expands the scientific capabilities of the project. I hope that we will be able to do all this with Luna-27.
— How is the work on scientific equipment for the devices going now?
— The equipment for the Luna-26 and Luna-27 missions has been practically created. Luna-26 will become a full-fledged and modern platform for remote exploration of the Moon from low orbit. The most important experiments will be radar to study the subsurface structure of the Moon, infrared, gamma-ray and neutron spectrometers to study the chemical composition, hydration and distribution of water ice in the subsurface layers. Important results are also expected from the television stereo system to build a fairly detailed topographic map of the Moon. A powerful plasma complex has also been installed on Luna-26 to study the features of the Moon's interaction with plasma flows of the solar wind. In addition, it is also possible to relay information from the lander to Earth using the Luna-26 radio complex.
Luna-27 will have a significantly expanded payload package compared to Luna-25: a large set of instruments for studying the plasma-dust exosphere of the Moon. These are equipment for studying the interaction of the Moon with the solar wind, and devices for measuring the properties of lunar dust and the electric fields generated by it. Generally speaking, the charged dust cloud, whose particles levitate above the surface of the Moon, has not been studied enough, although the negative effects of dust will certainly affect the future exploration of the Moon. It is not for nothing that Chinese colleagues became interested in these experiments, and Russian dust instruments similar to those prepared for Luna-27 are now planned to be installed on Chinese landing missions. Local studies of regolith and subsurface layers using an active neutron generator "Hadron", a laser mass spectrometer, and instruments for spectroscopy of the lunar surface in the infrared wavelength range will also become important. The thermal properties of the lunar regolith will be studied using instruments made at the IKI RAS and GEOHI RAS. The device will be equipped with a powerful television system created by specialists of the Department of Optical and Physical Research of the IKI RAS, which will provide panoramic observations of the landing area and will be used for manipulations during sampling of lunar soil intended for analysis by the apparatus's instruments.
It is important that the scientists of the ICI and the specialists of the NGO im. Lavochkin managed to solve all the difficult problems arising from the need for import substitution in the manufacture of both spacecraft and a complex of scientific equipment.
