The discovery of water on Mars and the Moon by European and American probes is primarily due to Russian scientists.
Behind the regular reports of new and new discoveries made by European and American missions, it eludes public attention that many of these discoveries have been made thanks to the work of Russian scientists, engineers and designers. Among such discoveries, one can especially single out the detection of traces of water on the nearest to us and, as it seemed, completely dry celestial bodies — the Moon and Mars. It is the Russian neutron detectors, working on foreign vehicles, helped to find water here, and in the future they will also be able to provide manned expeditions. The head of the Laboratory of Nuclear Physics Instruments of the Institute of Space Research (IKI) of the Russian Academy of Sciences, Candidate of Physics and Mathematics Maxim Mokrousov told Russian Planet why Western space agencies prefer exactly Russian neutron detectors.
- Spacecraft - and orbital, and descent, and planetary rovers - carry entire sets of instruments: spectrometers, altimeters, gas chromatographs, etc. Why are neutron detectors at many of them Russian? What is the reason?
- This is due to the victory of our projects in open tenders, which are carried out by the organizers of such missions. Like the competitors, we submit a proposal and try to prove that our device is optimal for this device. And now several times we have succeeded.
Our usual rival at such contests is the Los Alamos National Laboratory, the one where the Manhattan project was implemented and the first atomic bomb was created. And here, for example, to make a neutron detector for the MSL (Curiosity) rover our laboratory was invited specially, having learned about the new technology that we had. Created for the American rover DAN became the first neutron detector with active particle generation. It actually consists of two parts - the detector itself and the generator, in which electrons accelerated to very high speeds hit the tritium target and, in fact, a full-fledged, albeit miniature, thermonuclear reaction occurs with the release of neutrons.
Americans do not know how to make such generators, but our colleagues from the Moscow Research Institute of Automation named after Dukhov created it. In the Soviet years, it was a key center where "fuses" for nuclear warheads were developed, and today some of its products have a civil, commercial purpose. In general, such detectors with generators are used, for example, in the exploration of oil reserves - this technology is called neutron logging. We just took this approach and used it for the rover; so far no one has done this.
DAN Active Neutron Detector
Usage: Mars Science Laboratory Laboratory / Curiosity (NASA), from 2012 to the present. Mass: 2,1 kg (neutron detector), 2,6 kg (neutron generator). Power Consumption: 4,5 W (detector), 13 W (generator). Main results: detection of bound water in the soil at a depth of up to 1 m along the route of the rover.
Maxim Mokrousov: “Along almost the entire 10-kilometer route traveled by the rover, water in the upper layers of the soil was usually detected 2 – 5%. However, in May of this year, he came across an area in which either there are many times more water, or some unusual chemicals are present. Mars rover deployed and returned to a suspicious place. As a result, it turned out that the ground there is really unusual for Mars and consists mainly of silicon oxide. ”
- With generation, everything is about clear. How does neutron detection itself occur?
“We detect low-energy neutrons with proportional helium-3 counters — they work in DAN, LAND, MGSN and all our other instruments. A neutron caught in helium-3 “collapses” its core into two particles, which are then accelerated in a magnetic field, create an avalanche reaction and output a current (electrons) pulse.
Maxim Mokrousov and Sergey Kapitsa. Photo: From the personal archive
High-energy neutrons are detected in the scintillator by the flares that they create, falling into it, usually an organic plastic, such as stilbene. Well, gamma rays can detect crystals based on lanthanum and bromine. At the same time, even more efficient crystals based on cerium and bromine have recently appeared, we use them in one of our most recent detectors, in that it will fly to Mercury next year.
- And yet, why are Western spectators selected by Western spectators in such exactly open contests of Western space agencies, and other instruments are also Western, and Russian neutron detectors time after time?
- By and large, the whole thing is in nuclear physics: in this area we still remain one of the leading countries in the world. It's not just about weapons, but also about the mass of related technologies that our scientists are engaged in. Even during the USSR, it was possible to achieve such a good start, that even in the 1990s it was not possible to lose everything completely, but today we are again building up the pace.
It should be understood that the Western agencies themselves do not pay a penny for these our devices. All of them are made for the money of Roskosmos, as our contribution to foreign missions. In exchange, we get a high status of participants in international space research projects, and in addition, priority direct access to the scientific data that our tools collect.
We transmit these results after processing, so we are rightly considered to be co-authors of all the finds that were made thanks to our instruments. Therefore, all high-profile events with the detection of the presence of water on Mars and the Moon are, if not entirely, then our result in many respects.
We can once again recall one of our first detectors, the HEND, still working aboard the American Mars Odyssey probe. It was thanks to him that the map of the hydrogen content in the surface layers of the Red Planet was first compiled.
HEND neutron spectrometer
Usage: Mars Odyssey (NASA) spacecraft, from 2001 to the present. Weight: 3,7 kg. Power Consumption: 5,7 W. Main results: high-latitude distribution of water ice in the north and south of Mars with a resolution of about 300 km, observation of seasonal changes in polar caps.
Maxim Mokrousov: “Without false modesty I can say that at Mars Odyssey, which 15 will soon be in orbit for years, almost all devices have already started to fail, and only ours continue to work without problems. It operates in tandem with a gamma detector, in fact representing with it a single instrument covering a wide range of particle energies. ”
- Since we are talking about the results, what kind of scientific tasks perform such devices?
- Neutrons are the particles most sensitive to hydrogen, and if its atoms are present somewhere in the soil, neutrons are effectively inhibited by their nuclei. On the Moon or Mars, they can be created by galactic cosmic rays or emit a special neutron gun, and we, in fact, measure the neutrons reflected by the ground: the fewer of them, the more hydrogen.
Well, hydrogen, in turn, is most likely water, either in a relatively pure frozen form, or bound in the composition of hydrated minerals. The chain is simple: neutrons - hydrogen - water, so the main task of our neutron detectors is to search for water reserves.
We are practical people, and all this work is done for future manned missions to the same Moon or Mars, for their development. If you land on them, then water, of course, is the most significant resource that you will need to either deliver or extract locally. Electricity can be obtained using solar cells or nuclear sources. It’s harder with water: for example, the main cargo that today has to be delivered to cargo ships on the ISS is water. Every time they take it on 2 – 2,5 tons.
Neutron detector LAND
Usage: Lunar Reconnaissance Orbiter (NASA) spacecraft, from 2009 to the present. Weight: 26,3 kg. Power Consumption: 13 W. Main results: detection of potential water reserves at the South Pole of the Moon; building a global map of the neutron radiation of the Moon with a spatial resolution of 5 – 10 km.
Maxim Mokrousov: “In LAND we already used a collimator based on boron-10 and polyethylene, which blocks neutrons on the sides of the instrument's field of view. He more than doubled the mass of the detector, but allowed us to achieve a higher resolution when observing the lunar surface - I think this was the main advantage of the instrument, which allowed us to bypass colleagues from Los Alamos again. ”
- How many such devices have already been done? And how much is planned?
- It is easy to list them: these are already working HEND on the Mars Odyssey and LAND on the lunar LRO, DAN on the Curiosity rover, and BTN-M1 installed on the ISS. Here it is worth adding the NS-HAND detector, which became part of the Russian Phobos-Grunt probe and, unfortunately, was lost with it. Now, at different stages of readiness, we have four more such devices.
BTN-M1. Photo: Space Research Institute RAS
The first of these, already next summer, will be the FRAND detector, which will become part of the ExoMars mission joint with the EU. This mission is very ambitious, it will include the orbiter, the descent module, and the small rover, which will be launched separately during 2016 – 2018. FRAND will work on an orbital probe, and on it we use the same collimator as on the lunar LAND to measure the water content on Mars with the same accuracy with which it was done for the Moon. In the meantime, for Mars we have these data only in a rather crude approximation.
It has long been ready and handed over to our European partners the Mercurian gamma and neutron spectrometer (MGNS), which will work on the BepiColombo probe. It is planned that the launch will take place in the 2017 year, while the last thermal vacuum tests of the instrument are already in the spacecraft.
We are also preparing instruments for Russian missions - these are two ADRON detectors that will work as part of the Luna-Globe descent vehicles, and then Luna Resource. In addition, the BTN-M2 detector is in operation. It will not only conduct observations onboard the ISS, but also allow working out different methods and materials to effectively protect astronauts from the neutron component of cosmic radiation.
BTN-M1 neutron detector
Use: International Space Station (Roscosmos, NASA, ESA, JAXA, etc.), from 2007 year. Weight: 9,8 kg. Power Consumption: 12,3 W. Main results: maps of neutron fluxes in the vicinity of the ISS were constructed, the radiation situation at the station was estimated in connection with the activity of the Sun, an experiment on the registration of cosmic gamma bursts was conducted.
Maxim Mokrousov: “Having taken up this project, we were rather surprised: after all, in fact, different forms of radiation are different particles, including electrons, and protons, and neutrons. At the same time, it turned out that so far no one really measured the neutron component of radiation hazard, and this is its especially dangerous form, because neutrons are extremely difficult to shield using conventional methods. ”
- To what extent can these devices be called Russian? Is the share of elements and parts of domestic production in them large?
- Full-fledged mechanical production has been established here, at IKI RAN. We also have all the necessary test facilities: a shock stand, a vibration test bench, a thermal vacuum chamber, and an electromagnetic compatibility test camera ... In fact, we only need third-party production for individual components, say, printed circuit boards. With this we are helped by partners from the Research Institute of Electronic and Computer Engineering (NIICEVT), a number of commercial enterprises.
Previously, of course, there were a lot of our tools, somewhere 80%, of imported components. However, now the new devices manufactured by us are almost completely assembled from domestic components. I think the import in them in the near future will be no more than 25%, and in the future we will be even less dependent on foreign partners.
I can say that in recent years, domestic microelectronics has made a leap forward. Eight years ago, in our country, electronic boards that were suitable for our tasks were not produced at all. Now there are Zelenograd enterprises “Angstrom”, “Elvis” and “Milandr”, there is Voronezh NIIET - the choice is sufficient. It became easier for us to breathe.
The most annoying - unconditional dependence on the manufacturers of scintillator crystals for our detectors. As far as I know, attempts are being made to grow them in one of the institutes in the Moscow region of Chernogolovka, but so far they have not been able to achieve the required size and volume of ultrapure crystal. Therefore, in this regard, we still have to rely on European partners, more precisely, on the Saint-Gobain concern. However, the concern in this market is a complete monopolist, so the whole world remains in a dependent position.