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The closest to us and seemingly well-studied celestial body, the Moon, still causes serious scientific interest. How did water ice appear at the poles, and what is it like? Is this the stuff of comets and asteroids captured by “cold traps”? Or is it the result of volcanism when a very long time ago water was raised from the depths of the moon? What is its isotopic composition - does it coincide with the earthly one and can it say something about how water appeared on our planet? And how convenient will it be to use it to operate an inhabited base or to make rocket fuel out of it? Dust rises above the surface of the moon, very small concentrations of gaseous substances are recorded - this is called the exosphere. How does the exosphere of the moon, depending on the time of day,How does it react to gigantic temperature changes between day and night? The Luna-25 station will have to come closer to the answer to these questions, which may become the first spacecraft to land at the South Pole and the first Russian interplanetary station on the Moon already in the fall of 2021. Under the cut, the history of the apparatus and interviews with Igor Mitrofanov, head of the nuclear planetology department of the Space Research Institute of the Russian Academy of Sciences and one of the mission leaders.


«-25» . , Sputnik /


You experience a complex set of feelings when you find out that the idea of ​​the project, which is now called Luna-25, was born back in 1997. The date is not accidental - in November 1996, “Mars-96” could not fly beyond the Earth’s orbit, and, probably, there were discussions in the scientific and technical environment about which direction to move on. In 1998, the third International Conference on the Exploration and Exploration of the Moon was held in Moscow, at which a draft mission entitled “Moon-Globe” was presented. In the original version, a significant part was borrowed from Mars-96 - the mission's priority was seismic research, which was supposed to be carried out using penetrators submerging beneath the surface. The mission was very ambitious, which also resembled “Mars-96”.


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The device was to consist of three parts. Firstly, there was a cassette on board with ten penetrators created on the basis of Martian ones. It had to be separated at the approach, unwind and drop the penetrators in two steps, so that the first five moved sideways by about 10 km, the remaining 5 by about 5 km. Penetrators without braking had to hit the surface at a speed of 2.5 km / s, survive an overload of 100 thousand “same” and then work for a year, forming the so-called low-aperture seismic group or, in simple language, a seismic sensor distributed in space.

Secondly, there were two more broadband seismic receivers on board with a more careful landing program - braking at an altitude of 2 km to zero, acceleration in free fall to ~ 80 m / s and a fall with an overload of no more than 500 “same”. Located no closer than 300 km from each other in the equatorial region (Apollon-11 and -12 landing areas were proposed), seismometers would work in the “window” region of lesser attenuation of seismic vibrations.

The first and second sets of sensors would make it possible to determine with high accuracy the depth of the boundary between the core and the lower mantle of the Moon, which could answer the question about the origin of our satellite. For example, the giant collision hypothesis requires a very small core or none at all.

And finally, the kit included a landing station, the purpose of which was the shadow area at the south pole and the search for water ice there. Her tool kit included a TV camera (panorama and ice search), a neutron detector (search for water in rocks), spectrometers to determine the composition of surrounding rocks, a magnetometer, a probe with a thermometer, and an accelerometer to determine landing overload.


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But after the priority of financing was “Mars-96”, justice demanded the redistribution of funds in favor of astrophysics. So the Spectrum program was born, according to which the Spectrum-R flew in 2011, and the Spectrum-RG in 2019. Funding for a celestial body research program was declining. And in the summer of 1998, when there was only one place, Luna-Glob lost to Phobos-Grunt.

In the Martian shadow


Only eight years later, in the federal space program of 2006-2015, funds were allocated for development work on the Luna-Glob project. The project underwent changes, the penetrators were either removed or returned back, and, fortunately, good quality images have already been preserved from that period.


A variant of the station from the 2006 presentation , with antennas of the “wave channel” type and without penetrators.

The main surprise is the design of the landing apparatus, repeating the “E-6” project forty years ago (at that time).



As in 1966, the station was supposed to brake using the landing stage and at a low altitude and speed, reset the landing module with inflated shock-absorbing cylinders. Having jumped several times like a ball and stopped, the module would drop half the cylinders, open the petals, which would set it in the correct position, and get to work. Luny-9 and -13 operated on batteries and turned off after a few earth days, but compact RTGs were developed for similar small autonomous stations Mars-96 , so it’s impossible to talk about the estimated duration of the station’s operation. If such an apparatus really sat on the moon in the 21st century, it would be difficult not to feel awkward.

It is also clearly visible that the project was based on the developments of Phobos-Grunt - it was proposed to use engines, an on-board computer, star sensors and an electric power system.



Large antennas on an orbiting vehicle - the LORD astrophysical experiment , in which they planned to study cosmic rays and ultrahigh-energy neutrinos.

In another presentation , 2007, the apparatus has horn antennas and penetrators clearly visible.



But the concept of the “lunar polygon” looks great even now, it’s relevant, and I want to hope that it will be realized in some form. Because it, in fact, involves the construction of a distributed automatic lunar base that solves a wide variety of tasks.



The basis is a universal landing stage, capable of delivering a variety of cargoes to the surface: moon rovers, return vehicles, scientific and service modules. A fully developed base would raise the question of whether a person needs to return to the moon and what to do there besides servicing robots and selfies. Because such a training ground could solve all the urgent tasks of research and exploration of the Moon: the service area in practice would gain experience in the operation of technology in lunar conditions, the process area would study the processes of using local resources, construction and supply interesting geological materials. In the scientific zone, it would be possible to place telescopes of different wavelengths, send lunar rovers for reconnaissance and conduct research on the moon itself.

For history, it is worth noting that the earliest of the announced launch dates for the station was called 2012, but with the possibility of launching even earlier, in 2010.

Collaboration and rework


From the second half of the 2000s, work was simultaneously conducted to find international partners. The Japanese had great experience with penetrators, so the idea of ​​combining Luna-Glob with the Japanese mission Lunar-A was considered (it was finally canceled in 2007). India’s interest in the Moon gave rise to plans for joint projects, with the idea of ​​making the Luna Globe a lunar rover and placing it on the Indian Chandrayan-2, and later setting up the Indian lunar rover at the Russian landing station. But after the failure of Phobos-Grunt in 2011, the Russian side wanted to postpone the 2015 deadlines for redesigning the structure, which did not suit the Indians.

Changed and layout, in the “Bulletin of the NGO named after Lavochkina ”№4 2010 you can find a model with an octahedron from solar panels. Obviously, the station was already assumed to be long-lived.



And in the 2010-2011 region, a design appears that is indistinguishable from the “metal” currently being implemented: the solar panels have moved to the station end, the manipulator is clearly visible.



Final option


In 2013, the station was renamed, giving a much more successful, emphasizing the continuity with the Soviet lunar program and without any associations of the “globe” - “coffin” name “Luna-25”. The project was included in the 2016-2025 federal space program, money was allocated, and much more active work began. Of course, there was a time shift, they didn’t manage by 2019, and now, according to the latest news, the station should go on a flight on October 1, 2021 with a reserve date on October 30. Collaboration has also begun with the European Space Agency - in 2013, Roscosmos and ESA agreed that a Pilot-D camera would be installed on the Moon-25 to capture the landing process.

In the journal “Vestnik NPO im. Lavochkina ” No. 4 2016 presents the appearance, weight summary and components of the station.







The flight plan involves a flight to the moon with two trajectory corrections, a transition to a low lunar orbit and landing.





The task of landing in the area of ​​the South Pole went unchanged through all versions. As a result, the Boguslavsky crater area was chosen as the main one.


Bulletin of the NGO named after Lavochkina №2 2017

Interview


Interview taken by the correspondent of the portal N + 1.
N + 1: Will the launch date not change?

Igor Mitrofanov: Yes, it will be on October 1, 2021, and we have a second, reserve date on October 30, 2021. We determined this date a year or six months ago. The date is agreed with the Lavochkin NGO, and it is determined both by the conditions of the flight and the capabilities of the mass of the spacecraft.

Knowing all the problems that we have, I can argue that this date is final. Before, the situation changed very much, there were a lot of problems, it’s enough to call the sanctions, because of which some systems actually had to be re-developed. Now we have already reached the level of readiness that allows us to call this date final.

You can’t fly to the moon at any time, there are windows there too, as for expeditions to Mars?

The fact is that the spacecraft actually has a limit mass that we can put on board, and since the mission is polar, the amount of fuel that we can take does not allow us to fly every day. We must choose the time when the Moon and the Earth are located rather favorably with respect to each other, when we can take the maximum fuel supply to enter the polar orbit, make the necessary corrections in this orbit and land.

Each year there are several dates when such a flight is convenient to carry out. Lunar revolution - about one month, about 12 revolutions per year. You can fly starting in the summer, but only at the limit of the fuel reserve that we have, and October 1 is a convenient date when we have the maximum fuel reserve.
Another important limitation: we must fly in before the moonlit night comes. Lunar days last about 28 days, of which about half are daylight hours. It is not convenient to fly in from a lunar morning according to ballistic conditions, so it turns out that we have convenient dates come once a month, and somewhere, on a lunar day, landing will be late in the morning, that is, closer to noon. We will stay until the moonlit night for about a week.

You have two landing sites, when will you choose exactly where you will fly?

This will not change. The main landing area is the zone that is closer to the equator in relation to the Boguslavsky crater, and the decision to land in this area will be made when we are already flying. If an emergency occurs, it will take time to solve some problem, when the device will be in a lunar orbit, we will miss Boguslavsky, and in a few days - when the problem is resolved, we will land in the reserve area, in the vicinity of the Manzini Crater.


The main landing area is the number 11, the spare area is the area of ​​the numbers 2 and 3. Color intensity is the amount of water in the ground. Image of IKI RAS

Since this is our first landing, and this landing will be uncontrollable, the accuracy will be determined only by the path. The device will not be able to maneuver and change the place of contact. The calculated ellipse turned out to be quite large - 15 by 30 kilometers, so we mainly chose the area based on engineering considerations so that there were no large slopes, large boulders.

Only the next vehicle, Luna-27, will be able to maneuver during landing, and the accuracy of the Luna-25 landing will be determined only by how well we know its trajectory in orbit, the braking momentum, and then we will fly only by maneuvering in height. The device will not be able to maneuver in the horizontal coordinate.

Is the flight copy of the device ready?

He is being created. We are now at the stage of the beginning of assembly of the aircraft, despite the fact that many important tests of layouts have already passed, which made it possible to check the quality of individual systems. Almost all of the flight scientific equipment was delivered to the Lavochkin NPO, there are only three devices left that we must supply in May-June, now it is actually being integrated, and separate systems are being tested in parallel with the integration.

Complex tests, when the entire assembly is tested, will be held in the winter of 2020-2021 and in the spring of 2021. The flight instance should be ready for launch in early summer 2021. The launch will be from the Vostochny spaceport on the Soyuz launch vehicle.

Do Europeans participate in the project?

Since the European Space Agency is participating in the next lunar probe “Luna-27” - they are developing systems for high-precision controlled landing, at their request we installed onboard a television camera similar to the one that will work on the next device - so that according to the image of the surface conduct active maneuvers on landing. This camera will help to aim more precisely or, if it is clear that we are sitting on a steep slope or a large cobblestone, to perform an evasion maneuver. And the camera, which should work on the 27th “Moon”, will receive the first flight experience on the “Moon-25”. She will not control the landing, she will capture the image of the surface. True, it will not transmit an image live - for this, an orbital repeater is needed.

When we sit down, if all goes well, we will establish a radio channel, and through this channel we will transmit a recording of the moment of landing. Europeans from this picture will work out their image processing algorithms, signal generation.

How long will the unit live?

Year. He has two technological tasks: to sit down successfully and survive the moonlit night. The scientific program for the first lunation is very limited, for us the main thing is to prepare the device for the night. This is still the poles. There is no fundamental difference with the equator, but the sun is lower, the sunrises later, the moonlit night is slightly longer.

We will prepare for the moonlit night, and the main thing is to survive it well, so that in the morning we “wake up” efficient, so that we can work out the full period of the day for science. Rigit will provide overnight - radioisotope sources of energy on board, without them you can not survive a moonlit night.

How many scientific instruments will be on board?

I can’t say definitively which devices will remain on board. The fact is that we have exceeded the mass. The excess is very small, on the order of several kilograms, but this is a problem that remains to be solved.

We agreed with the Lavochkin NGO that when the final weighing of the apparatus takes place - not an estimate based on the drawings, but the real mass, taking into account the cables, connectors, all sorts of details, we will determine which devices fly. It is necessary to weigh the real apparatus, with such a large mass - several tons - the error can be within a few kilograms.

Now all devices are ready, all devices can fly, but when such a measurement occurs, and with full tanks, we can fly - we will finally understand after that, maybe we will need to part with some part of the payload.

But it is important to note that the Luna-27 will fly next, and all devices that cannot fly the Luna-25 will fly on it.

What scientific tasks will the mission solve?

We have two main tasks. The first is the study of the lunar polar regolith, because we understand that it is different, different from what we studied and brought in the 20th century, because there are volatile compounds, including water, in this polar regolith. And the second is the study of the lunar exosphere.

On board there are two devices that will study this regolith based on remote measurements and direct contact.

This is the ADRON-LR device , which will irradiate the surface with neutrons, and by the neutron albedo we will judge what kind of chemical composition there is and how much water ice.

The second device is LIS, a lunar infrared spectrometer to be mounted on a manipulator. This is a device with a narrow field of view that will look at the spectrum of reflected infrared radiation. Since water and hydroxyl leave certain spectral lines in the infrared range, by registering these lines it will be possible to estimate the water content in the substance that the lens of this device is aimed at.

In addition, the LASMA device will study regolithbut by contact methods. The manipulator will remove the topsoil next to the landing site - to remove contaminants that arise from the operation of the engines, and then take about a dozen samples. They will be loaded into the LASMA device, where the laser will vaporize this substance. The gas will be examined using a mass spectrometer, and from the lines we can determine the chemical composition of regolith.

These are three devices that will study the lunar matter, and there will also be devices that are designed to study the exosphere - the extremely rarefied gas shell of the moon. It consists of a plasma component, a neutral component, and a dust component. ARIES deviceit will record secondary ions and neutral atoms that the solar wind flux knocks out of regolith, and the PML device will study the composition and dynamics of moon dust and electric fields in the vicinity of the landing site.
This is a very interesting task - to study how the behavior of atoms and ions changes during a lunar day, how the moon dust levitates in electric fields induced by ultraviolet solar radiation. The lunar exosphere has been studied for a long time, in particular, it was studied by the American LADEE apparatus, but we will observe its behavior in the vicinity of the pole, we can see effects that were not observed in the equatorial zones.

Material prepared for the portal N + 1 , published in the original edition.

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