Already at the end of this decade, Russia may create spaceship for interplanetary travel on nuclear power. And this will dramatically change the situation both in near-Earth space and on the Earth itself.
The nuclear power plant (NPP) will be ready for flight in 2018. This was announced by the director of the Keldysh Center, academician Anatoly Koroteev. “We must prepare the first sample (of a megawatt-class nuclear power plant. – Expert Online’s note) for flight tests in 2018. Whether she will fly or not is another matter, there may be a queue, but she must be ready to fly,” RIA Novosti reported his words. The above means that one of the most ambitious Soviet-Russian projects in the field of space exploration is entering the phase of immediate practical implementation.
The essence of this project, the roots of which go back to the middle of the last century, is this. Now flights into near-Earth space are carried out on rockets that move due to the combustion of liquid or liquid in their engines. solid fuel. Essentially, this is the same engine as in a car. Only in a car does gasoline, when burned, push the pistons in the cylinders, transferring its energy through them to the wheels. And in a rocket engine, burning kerosene or heptyl directly pushes the rocket forward.
Over the past half century, this rocket technology has been perfected all over the world to the smallest detail. But the rocket scientists themselves admit that . Improvement - yes, it is necessary. Trying to increase the payload of rockets from the current 23 tons to 100 and even 150 tons based on “improved” combustion engines - yes, you need to try. But this is a dead end from an evolutionary point of view. " No matter how much rocket engine specialists around the world work, the maximum effect we get will be calculated in fractions of a percent. Roughly speaking, everything has been squeezed out of existing rocket engines, be they liquid or solid fuel, and attempts to increase thrust and specific impulse are simply futile. Nuclear power propulsion systems provide a multifold increase. Using the example of a flight to Mars, now it takes one and a half to two years to fly there and back, but it will be possible to fly in two to four months “- the former head of the Russian Federal Space Agency assessed the situation at one time Anatoly Perminov.
Therefore, back in 2010, the then President of Russia, and now Prime Minister Dmitry Medvedev By the end of this decade, an order was given to create in our country a space transport and energy module based on a megawatt-class nuclear power plant. It is planned to allocate 17 billion rubles from the federal budget, Roscosmos and Rosatom for the development of this project until 2018. 7.2 billion of this amount was allocated to the Rosatom state corporation for the creation of a reactor plant (this is being done by the Dollezhal Research and Design Institute of Energy Engineering), 4 billion - to the Keldysh Center for the creation of a nuclear power propulsion plant. 5.8 billion rubles are allocated by RSC Energia to create a transport and energy module, that is, in other words, a rocket ship.
Naturally, all this work is not done in a vacuum. From 1970 to 1988, the USSR alone launched more than three dozen spy satellites into space, equipped with low-power nuclear power plants such as Buk and Topaz. They were used to create an all-weather system for monitoring surface targets throughout the World Ocean and issuing target designation with transmission to weapon carriers or command posts - the Legend naval space reconnaissance and target designation system (1978).
NASA and American companies that produce spacecraft and their delivery vehicles have not been able to create a nuclear reactor that would operate stably in space during this time, although they tried three times. Therefore, in 1988, a ban was passed through the UN on the use of spacecraft with nuclear power propulsion systems, and the production of satellites of the US-A type with nuclear propulsion on board in the Soviet Union was discontinued.
In parallel, in the 60-70s of the last century, the Keldysh Center conducted active work to create an ion engine (electroplasma engine), which is most suitable for creating a high-power propulsion system operating on nuclear fuel. The reactor produces heat, which is converted into electricity by a generator. With the help of electricity, the inert gas xenon in such an engine is first ionized, and then positively charged particles (positive xenon ions) are accelerated in an electrostatic field to a given speed and create thrust when leaving the engine. This is the operating principle of the ion engine, a prototype of which has already been created at the Keldysh Center.
« In the 90s of the 20th century, we at the Keldysh Center resumed work on ion engines. Now a new cooperation must be created for such a powerful project. There is already a prototype of an ion engine on which basic technological and design solutions can be tested. But standard products still need to be created. We have a set deadline - by 2018 the product should be ready for flight tests, and by 2015 the main engine testing should be completed. Next - life tests and tests of the entire unit as a whole.“, noted last year the head of the electrophysics department of the Research Center named after M.V. Keldysh, professor of the Faculty of Aerophysics and space research MIPT Oleg Gorshkov.
What is the practical benefit for Russia from these developments? This benefit far exceeds the 17 billion rubles that the state intends to spend by 2018 on creating a launch vehicle with a nuclear power plant on board with a capacity of 1 MW. Firstly, this is a dramatic expansion of the capabilities of our country and humanity in general. A nuclear-powered spacecraft provides real opportunities for people to accomplish things on other planets. Now many countries have such ships. They also resumed in the United States in 2003, after the Americans received two samples of Russian satellites with nuclear power plants.
However, despite this, a member of the NASA special commission on manned flights Edward Crowley for example, he believes that a ship for an international flight to Mars should have Russian nuclear engines. " Russian experience in the development of nuclear engines is in demand. I think Russia has a lot of experience both in the development of rocket engines and in nuclear technology. She also has extensive experience in human adaptation to space conditions, since Russian cosmonauts made very long flights “,” Crowley told reporters last spring after a lecture at Moscow State University on American plans for manned space exploration.
Secondly, such ships make it possible to sharply intensify activity in near-Earth space and provide a real opportunity to begin the colonization of the Moon (there are already projects for the construction of nuclear power plants on the Earth’s satellite). " The use of nuclear propulsion systems is being considered for large manned systems, rather than for small spacecraft, which can fly on other types of installations using ion engines or solar wind energy. Nuclear propulsion systems with ion engines can be used on an interorbital reusable tug. For example, transport cargo between low and high orbits, and fly to asteroids. You can create a reusable lunar tug or send an expedition to Mars“, says Professor Oleg Gorshkov. Ships like these are dramatically changing the economics of space exploration. According to calculations by RSC Energia specialists, a nuclear-powered launch vehicle reduces the cost of launching a payload into lunar orbit by more than half compared to liquid rocket engines.
Third, these are new materials and technologies that will be created during the implementation of this project and then introduced into other industries - metallurgy, mechanical engineering, etc. That is, this is one of those breakthrough projects that can really push both the Russian and global economies forward.
The idea of throwing atomic bombs behind the stern turned out to be too brutal, but the amount of energy that the nuclear fission reaction produces, not to mention fusion, is extremely attractive for astronautics. Therefore, many non-pulse systems were created, freed from the problems of storing hundreds of nuclear bombs on board and cyclopean shock absorbers. We'll talk about them today.
Nuclear physics at your fingertips
What is a nuclear reaction? To explain it very simply, the picture will be something like this. From the school curriculum we remember that matter consists of molecules, molecules are made of atoms, and atoms are made of protons, electrons and neutrons (there are lower levels, but this is enough for us). Some heavy atoms have an interesting property - if they are hit by a neutron, they decay into lighter atoms and release several neutrons. If these released neutrons hit other heavy atoms nearby, the decay will repeat, and we will get a nuclear chain reaction. The movement of neutrons at high speed means that this movement turns into heat when the neutrons slow down. Therefore, a nuclear reactor is a very powerful heater. They can boil water, send the resulting steam to a turbine, and get a nuclear power plant. Or you can heat hydrogen and throw it outside, creating a nuclear jet engine. From this idea the first engines were born - NERVA and RD-0410.
NERVA
Project history
The formal authorship (patent) for the invention of the atomic rocket engine belongs to Richard Feynman, according to his memoirs “You're Surely Joking, Mr. Feynman.” The book, by the way, is highly recommended reading. Los Alamos Laboratory began developing nuclear rocket engines in 1952. In 1955 the Rover project was started. At the first stage of the project, KIWI, 8 experimental reactors were built and from 1959 to 1964, the purging of working fluid through the reactor core was studied. For time reference, the Orion project existed from 1958 to 1965. Rover had phases two and three exploring higher power reactors, but NERVA was based on KIWI due to plans for the first test launch in space in 1964 - there was no time to develop more advanced options. The deadlines gradually moved forward and the first ground launch of the NERVA NRX/EST engine (EST - Engine System Test - test motor system) took place in 1966. The engine operated successfully for two hours, of which 28 minutes were at full thrust. The second NERVA XE engine was started 28 times and ran for a total of 115 minutes. The engine was deemed suitable for space applications, and the test bench was ready to test the newly assembled engines. It seemed that NERVA had a bright future ahead of it - a flight to Mars in 1978, a permanent base on the Moon in 1981, orbital tugs. But the success of the project caused panic in Congress - the lunar program turned out to be very expensive for the United States, the Mars program would be even more expensive. In 1969 and 1970, space funding was seriously reduced - Apollos 18, 19 and 20 were cancelled, and no one would allocate huge amounts of money for the Mars program. As a result, work on the project was carried out without serious funding and it was closed in 1972.Design
Hydrogen from the tank entered the reactor, was heated there, and was thrown out, creating jet thrust. Hydrogen was chosen as the working fluid because it has light atoms and is easier to accelerate to high speed. The higher the jet exhaust speed, the more effective rocket engine.
A neutron reflector was used to ensure that neutrons were returned back to the reactor to maintain a nuclear chain reaction.
Control rods were used to control the reactor. Each such rod consisted of two halves - a reflector and a neutron absorber. When the rod was turned by the neutron reflector, their flow in the reactor increased and the reactor increased heat transfer. When the rod was turned by the neutron absorber, their flow in the reactor decreased, and the reactor reduced heat transfer.
Hydrogen was also used to cool the nozzle, and warm hydrogen from the nozzle cooling system rotated the turbopump to supply more hydrogen.
The engine is running. Hydrogen was specially ignited at the exit of the nozzle in order to avoid the threat of an explosion; there would be no combustion in space.
The NERVA engine produced 34 tons of thrust, about one and a half times less than the J-2 engine that powered the second and third stages of the Saturn V rocket. The specific impulse was 800-900 seconds, which was twice as high as the best engines using the oxygen-hydrogen fuel pair, but less than the electric propulsion system or the Orion engine.
A little about security
A nuclear reactor that has just been assembled and not started up, with new fuel assemblies that have not yet been used, is quite clean. Uranium is poisonous, so you need to wear gloves, but nothing more. No remote manipulators, lead walls or anything else is needed. All radiating dirt appears after the reactor is started due to scattering neutrons, “spoiling” the atoms of the vessel, coolant, etc. Therefore, in the event of a rocket accident with such an engine, radiation contamination of the atmosphere and surface would be small, and, of course, it would be much less than the normal launch of Orion. In the event of a successful launch, contamination would be minimal or absent altogether, because the engine would have to be launched in the upper layers of the atmosphere or already in space.RD-0410
The Soviet RD-0410 engine has a similar history. The idea of the engine was born in the late 40s among the pioneers of rocket and nuclear technology. As in the Rover project, the original idea was a nuclear-powered air-breathing engine for the first stage of a ballistic missile, then development moved into the space industry. The RD-0410 was developed more slowly; domestic developers were carried away by the idea of a gas-phase nuclear propulsion engine (more on this below). The project began in 1966 and continued until the mid-80s. The target for the engine was the Mars 94 mission, a manned flight to Mars in 1994.
The RD-0410 design is similar to NERVA - hydrogen passes through the nozzle and reflectors, cooling them, is supplied to the reactor core, heated there and released.
According to its characteristics, RD-0410 was better than NERVA - the temperature of the reactor core was 3000 K instead of 2000 K for NERVA, and the specific impulse exceeded 900 s. RD-0410 was lighter and more compact than NERVA and developed ten times less thrust.
Engine tests. The side torch on the lower left ignites the hydrogen to prevent an explosion.
Development of solid-phase nuclear propulsion engines
We remember that the higher the temperature in the reactor, the greater the flow rate of the working fluid and the higher the specific impulse of the engine. What prevents you from increasing the temperature in NERVA or RD-0410? The fact is that in both engines the fuel elements are in a solid state. If you increase the temperature, they will melt and fly out along with the hydrogen. Therefore, for higher temperatures it is necessary to come up with some other way to carry out a nuclear chain reaction.Nuclear fuel salt engine
In nuclear physics there is such a thing as critical mass. Remember the nuclear chain reaction at the beginning of the post. If fissile atoms are very close to each other (for example, they were compressed by pressure from a special explosion), then an atomic explosion will result - a lot of heat in a very short time. If the atoms are not compressed so tightly, but the flow of new neutrons from fission increases, a thermal explosion will result. A conventional reactor would fail under such conditions. Now imagine that we take an aqueous solution of fissile material (for example, uranium salts) and feed them continuously into the combustion chamber, providing there a mass greater than the critical one. What you get is a continuously burning nuclear “candle”, the heat from which accelerates the reacted nuclear fuel and water.
The idea was proposed in 1991 by Robert Zubrin and, according to various estimates, promises a specific impulse of 1300 to 6700 s with a thrust measured in tons. Unfortunately, such a scheme also has disadvantages:
- Complexity of fuel storage - chain reaction in the tank must be avoided by placing the fuel in, for example, thin tubes from a neutron absorber, so the tanks will be complex, heavy and expensive.
- The high consumption of nuclear fuel is due to the fact that the efficiency of the reaction (the number of decayed/number of atoms spent) will be very low. Even in an atomic bomb, the fissile material does not “burn” completely; immediately, most of the valuable nuclear fuel will be wasted.
- Ground tests are practically impossible - the exhaust of such an engine will be very dirty, dirtier even than the Orion.
- There are some questions about controlling the nuclear reaction - it is not a fact that a scheme that is simple in verbal description will be easy to technically implement.
Gas-phase nuclear propulsion engines
Next idea: what if we create a working fluid vortex, in the center of which a nuclear reaction will take place? In this case, the high temperature of the core will not reach the walls, being absorbed by the working fluid, and it can be raised to tens of thousands of degrees. This is how the idea of an open-cycle gas-phase nuclear propulsion engine was born:
The gas-phase nuclear propulsion engine promises a specific impulse of up to 3000-5000 seconds. In the USSR, a project of a gas-phase nuclear propulsion engine (RD-600) was started, but it did not even reach the mock-up stage.
"Open cycle" means that nuclear fuel will be released outside, which, of course, reduces efficiency. Therefore, the following idea was invented, dialectically returning to solid-phase NREs - let's surround the nuclear reaction region with a sufficiently heat-resistant substance that will transmit radiated heat. Quartz was proposed as such a substance, because at tens of thousands of degrees, heat is transferred by radiation and the container material must be transparent. The result is a gas-phase closed-cycle nuclear propulsion engine, or a “nuclear light bulb”:
In this case, the limit on the core temperature will be the thermal strength of the “light bulb” shell. The melting point of quartz is 1700 degrees Celsius, with active cooling the temperature can be increased, but, in any case, the specific impulse will be lower than the open circuit (1300-1500 s), but nuclear fuel will be consumed more economically, and the exhaust will be cleaner.
Alternative projects
In addition to the development of solid-phase nuclear propulsion engines, there are also original projects.Fissile engine
The idea of this engine is that there is no working fluid - it is the ejected spent nuclear fuel. In the first case, subcritical disks are made from fissile materials, which do not start a chain reaction on their own. But if the disk is placed in a reactor zone with neutron reflectors, a chain reaction will start. And the rotation of the disk and the absence of a working fluid will lead to the fact that the decayed high-energy atoms will fly away into the nozzle, generating thrust, and the undecayed atoms will remain on the disk and will get a chance at the next revolution of the disk:
An even more interesting idea is to create a dusty plasma (remember on the ISS) from fissile materials, in which the decay products of nuclear fuel nanoparticles are ionized by an electric field and thrown out, creating thrust:
They promise a fantastic specific impulse of 1,000,000 seconds. Enthusiasm is dampened by the fact that the development is at the level of theoretical research.
Nuclear fusion engines
In an even more distant future, the creation of nuclear fusion engines. Unlike nuclear fission reactions, where atomic reactors were created almost simultaneously with the bomb, fusion reactors have not yet moved from “tomorrow” to “today” and fusion reactions can only be used in the “Orion” style - throwing thermonuclear bombs.Nuclear photon rocket
Theoretically, it is possible to heat the core to such an extent that thrust can be created by reflecting photons. Despite the absence of technical limitations, such engines at the current level of technology are unprofitable - the thrust will be too low.Radioisotope rocket
A rocket that heats the working fluid from an RTG will be fully functional. But an RTG generates relatively little heat, so such an engine will be very inefficient, although very simple.Conclusion
At the current level of technology, it is possible to assemble a solid-state nuclear propulsion engine in the style of NERVA or RD-0410 - the technologies have been mastered. But such an engine will lose to the “nuclear reactor + electric propulsion” combination in terms of specific impulse, while winning in terms of thrust. But more advanced options are still only on paper. Therefore, I personally think the “reactor + electric propulsion” combination is more promising.Information sources
The main source of information is the English Wikipedia and the resources listed there as links. Paradoxically, there are interesting articles on NRE on Tradition - solid-phase NRE and gas-phase NRE. Article about engines on Nuclear enginesAt the end of the 40s, in the wake of euphoria from the prospects of using nuclear energy, both the USA and the USSR began work on installing nuclear engines on everything that could move. The idea of creating such a “perpetual” engine was especially attractive for the military. Nuclear power plants (NPPs) were primarily used in the navy because ship power plants were not subject to such stringent size and weight requirements as, for example, in aviation. Nevertheless, the Air Force could not “pass by” the opportunity to unlimitedly increase the range of strategic aviation. However, by this time the Americans realized that the open circuit was not suitable, and began designing a power plant with air heating in a heat exchanger. The new Convair NX-2 had a canard design (the horizontal tail was located in front of the wing). The nuclear reactor was to be located in the center section, the engines in the rear, and the air intakes under the wing. The aircraft was supposed to use from 2 to 6 auxiliary turbojet engines. But in March 1961 the ANP program was closed. University of California. Since 1956, all the efforts of the Radiation Laboratory have been aimed at creating a nuclear ramjet engine (NRJE) according to the PLUTO project (at Los Alamos they began to create a nuclear ramjet engine).
The nuclear-powered jet engine was planned to be installed on a supersonic low-altitude missile (SLAM) that was being developed. The missile (now it would be called a cruise missile) was essentially an unmanned bomber with a vertical launch (using four solid-fuel boosters). The nuclear jet engine was turned on when a certain speed was reached and already at a sufficient distance from its own territory. The air entering through the air intake was heated in the nuclear reactor and, flowing through the nozzle, created thrust. The flight to the target and the release of warheads for stealth purposes had to be carried out at ultra-low altitude at a speed three times the speed of sound. The nuclear reactor had a thermal power of 500 MW, the operating temperature of the core was more than 1600 degrees C. A special testing ground was built to test the engine. |  |
The Soviet Union needed a nuclear aircraft much more than the United States, since it did not have military bases near the US borders and could only operate from its territory, and the M-4 and Tu-95 strategic bombers that appeared in the mid-50s could not “cover” the entire US territory. Work on studying the problems of creating nuclear power plants for ships, submarines and aircraft began already in 1947. However, the resolution of the Council of Ministers on the start of work on nuclear-powered aircraft was issued only on August 12, 1955. (by this time the first Soviet nuclear submarine was already being built). Tupolev's OKB-156 and Myasishchev's OKB-23 began designing aircraft with nuclear power plants, and Kuznetsov's OKB-276 and Lyulka's OKB-165 were developing such power plants themselves. 
In March 1956 A government decree was issued on the creation (to study the influence of radiation on the design of an aircraft and its equipment, as well as radiation safety issues) of a flying laboratory based on the Tu-95 strategic bomber. In 1958 An experimental, “aircraft” nuclear reactor was delivered to the Semipalatinsk test site. In mid-1959 The reactor was installed on a production aircraft designated Tu-95LAL (Flying Atomic Laboratory). The reactor is used 
Its four NK-12M engines (Kuznetsov OKB) in addition to the combustion chambers were equipped with heat exchangers heated by a liquid metal coolant that took heat from a nuclear reactor located in the cargo compartment. The engines were designated NK-14A. In the future, it was planned to create an anti-submarine aircraft with an almost unlimited flight duration by installing 4 NK-14A engines on the aircraft and increasing the diameter of the fuselage. However, the design of the NK-14A engines, or rather its nuclear part, proceeded slowly due to the many problems that arose during this process. As a result, plans to create the Tu-119 were never realized. In addition, OKB-156 offered several options for supersonic bombers. Long-range bomber Tu-120 with a take-off weight of 85 tons. 30.7 m long. wingspan 24.4 m. And 
maximum speed of about 1400 km/h. Another project was a low-altitude attack aircraft with a take-off weight of 102 tons. 37m long. wingspan 19m. and a maximum speed of 1400 km/h. The plane had a low-lying delta wing. Its two engines were located in one package at the rear of the fuselage. During takeoff and landing, the engines ran on kerosene. The supersonic strategic bomber was supposed to have a take-off weight of 153 tons. length 40.5 m. and wingspan 30.6 m. Of the six turbojet engines (Kuznetsov Design Bureau), two, located in the tail, were equipped with heat exchangers and could be powered by a nuclear reactor. Four conventional turbojet engines were placed under the wing on pylons. Externally, this aircraft was similar to the American B-58 medium supersonic bomber. 
Arrangement options with different types of engines (take-off weight 225-250t, payload - 25t, speed - up to 3000 km/h, length 51-59m, wingspan - 27-31m). To protect against radiation, the pilots were placed in a special sealed capsule and the engines were placed in the rear fuselage. Visual visibility from the capsule was excluded and the autopilot had to guide the plane to the target. To ensure manual control, it was planned to use television and radar screens. The developers initially proposed making the plane unmanned. But for the sake of reliability, the military insisted on a manned version. One option was a seaplane. Its advantage was that the damped reactors could be lowered into water to reduce background radiation. With the development of rocket science and the advent of reliable intercontinental ballistic missiles and nuclear missile submarines, military interest in nuclear bombers faded and work was curtailed. But in 1965 the idea of creating a nuclear-powered anti-submarine aircraft was returned to again. This time the prototype was the heavy transport An-22 “Antey”, which had the same engines as the Tu-95. The development of the NK-14A was quite advanced by that time. Take-off and landing were to be carried out on kerosene (engine power 4 x 13000 hp), and cruising flight - on nuclear energy (4 x 8900 hp). The flight duration was limited only by the “human factor”; to limit the dose received by the crew, it was set to 50 hours. The flight range would be 27,500 km. In 1972 The An-22 with a nuclear reactor on board made 23 flights; first of all, radiation protection was checked. However, environmental problems in the event of an airplane accident were never resolved, perhaps this was the reason that the project was not implemented. In the 80s there was interest in, as a carrier of ballistic missiles. Being almost constantly in the air, it would be invulnerable to a sudden enemy nuclear missile strike. In the event of an airplane accident, the nuclear reactor could be separated and lowered by parachute. But the beginning of detente, “perestroika” and then the collapse of the USSR did not allow the nuclear plane to take off. In the mid-50s, OKB-301 (chief designer S.A. Lavochkin) worked on the issue of installing a ramjet nuclear engine on the Burya intercontinental cruise missile (similar to the PLUTO project). The project received the designation "375". The development of the rocket itself was not a problem; the engine engineers failed. OKB-670 (chief designer M.M. Bondaryuk) for a long time could not cope with the creation of a ramjet nuclear engine. In 1960 The Tempest project was closed along with its nuclear version. It never got to the point of testing a nuclear engine. evaporates RT, turning it into plasma. The expanding plasma cloud puts pressure on the powerful metal bottom (pusher plate) and creates jet thrust. A solid substance that can be easily converted into gas, applied to a pusher plate, liquid hydrogen or water stored in a special tank can be used as RT. This is a scheme of the so-called pulsed external-action NPP; another type is the internal-action pulsed NPP, in which the detonation of small nuclear or thermonuclear charges is carried out inside special chambers (combustion chambers) equipped with jet nozzles. RT is also supplied there, which, flowing through the nozzle, creates thrust like conventional liquid-propellant rocket engines. Such a system is more efficient, since all the RT and explosion products are used to create thrust. However, the fact that explosions occur inside a certain volume imposes restrictions on the pressure and temperature in the combustion chamber. An external pulsed nuclear propulsion engine is simpler, and the huge amount of energy released in nuclear reactions makes it possible to obtain even with a lower efficiency good characteristics such systems. 
10 m. The effective thrust accordingly decreased to 350 tons with its own “dry” weight of the propulsion system (without RT) of 90.8 tons. To deliver a payload of 680 tons to the lunar surface. it would be necessary to explode about 800 plutonium charges (plutonium mass 525 kg) and consume about 800 tons. RT. The option of using Orion as a means of delivering nuclear charges to a target was also considered. But the military soon abandoned this idea. And in 1963 An agreement was signed banning nuclear explosions in space on earth (in the atmosphere) and under water. This outlawed the entire project. A similar project was considered in the USSR, but it did not have any practical results. Just like the Myasishchev Design Bureau’s M-19 aerospace aircraft (VKS) project. The project envisaged the creation of a reusable, single-stage aerospace system capable of launching a payload weighing up to 40 tons into low reference orbits (up to 185 km). For this purpose, the VKS was supposed to be equipped with a nuclear propulsion engine and a multi-mode air-breathing propulsion system operating both from a nuclear reactor and on hydrogen fuel. More details about this project are described on the page. In the USA in 1958–63. A project for a rocket with a pulsed nuclear propulsion engine "Orion" was being developed. A model of an aircraft with a pulse engine was even tested using conventional chemical explosives. The results obtained indicated the fundamental possibility of controlled flight of the vehicle using such an engine. Initially, Orion was supposed to be launched from Earth. To exclude the possibility of damage to the rocket from a ground-based nuclear explosion, it was planned to install it on eight 75-meter towers for launch. At the same time, the launch mass of the rocket reached 10,000 tons. and the diameter of the pushing plate is about 40m. To reduce dynamic loads on the rocket structure and crew, a damping device was provided. After a compression cycle, it returned the plate to its initial position, after which another explosion occurred. At launch, a charge with a power of 0.1 kt was detonated every second. After leaving the atmosphere, charges with a power of 20 kt. exploded every 10 seconds. Later, in order not to pollute the atmosphere, it was decided to lift Orion from the Earth using the first stage of the Saturn-5 rocket, since its maximum diameter was 10 m. then the diameter of the pushing plate was cut to. Then the plasma is accelerated in an electromagnetic field (“gas-dynamic acceleration can also be used in parallel”). Low molecular weight or easily dissociating gases and liquids are used as RT in electrothermal electric propulsion engines; in electrostatic ones, alkaline or heavy, easily evaporating metals or organic liquids; in electromagnetic ones, various gases and solids are used. An important parameter of the engine is its specific thrust impulse (see page) characterizing its efficiency (the larger it is, the less PT is spent on creating a kilogram of thrust). Specific impulse for different types engines varies over a wide range: solid propellant thruster - 2650 m/s, liquid propellant rocket engine - 4500 m/s, electrochemical thruster - 3000 m/s, plasma thruster up to 290 thousand. As is known, the specific impulse value is directly proportional from the RT temperature in front of the nozzle. It (temperature) in turn is determined by the calorific value of the fuel. The best indicator among chemical fuels is beryllium + oxygen pair - 7200 kcal/kg. The calorific value of Uranium-235 is approximately 2 million times higher. However, the amount of energy that can be usefully used is only 1400 times greater. Limitations imposed by design features reduce this figure for a solid-phase nuclear propulsion engine to 2-3 (the maximum achievable RT temperature is about 3000 degrees). And yet, the specific impulse of a solid-phase nuclear-propellant rocket engine is approximately 9000 m/s, versus 3500-4500 for modern liquid-propellant rocket engines. For liquid-phase nuclear engines, the specific impulse can reach 20,000 m/sec; for gas-phase ones, where the RT temperature can reach tens of thousands of degrees, the specific impulse is 15-70 thousand m/sec. Thus, the main advantage of nuclear engines over other types of rocket engines is their large specific impulse, with a high thrust-to-weight ratio (tens, hundreds and thousands of tons of thrust with a significantly lower dead weight). The main disadvantage of the NRE is the presence of a powerful flow of penetrating radiation as well as the removal of highly radioactive uranium compounds from the spent RT. In this regard, the nuclear powered rocket engine is unacceptable for ground launches. In mid-1959 OKB-1 issued technical specifications to engine engineers (OKB-670 and OKB-456) for the development of preliminary designs of nuclear powered engines with a thrust of 200 and 40 tons. After the start of work on the N-1 heavy launch vehicle, the issue of creating a two-stage launch vehicle with a nuclear propulsion engine in the second stage was considered on its basis. This would ensure an increase in the payload launched into low-Earth orbit by no less than 2-2.5 times, and the lunar satellite orbit by 75-90%. But this project was not completed either - the N-1 rocket never flew. To ensure environmental safety, the stand was built according to a “closed” scheme - the waste coolant was kept in gas tanks before being released into the atmosphere, and then filtered. Since 1962 At the IGR (RVD), tests of fuel rods and fuel assemblies (FA) of various types were carried out for nuclear-powered reactors developed at NII-9 and NII-1. square root special additives were added to it). Some of the nuclear fuel was inevitably carried away by the gas flow, so it was necessary to constantly compensate for the loss of uranium. A gas-phase nuclear propulsion engine could have a specific impulse of up to 20,000 m/sec. Work on such an engine began in 1963. at OKB-456 (under the scientific leadership of NII-1). An extensive research program was carried out on it. power start-up was carried out. During which a power of 25 MW was achieved (15% of the design), the hydrogen temperature was 1500 degrees, the operating time was 70 seconds. During tests on July 3, 1978. and August 11, 1978 A power of 33 MW and 42 MW was achieved; the hydrogen temperature was 2360 degrees. In the late 70s and early 80s, two more series of tests were carried out at the bench complex - the second and third 11B91-IR-100 devices. Testing of fuel assemblies in the IGR and IVG reactors continued, and construction of structures was underway with the goal of commissioning a second-B workplace for testing the liquid hydrogen engine. The first experimental electric propulsion engine was created at the Gas Dynamics Laboratory (Leningrad) under the leadership of V.P. Glushko in 1929-1933. The study of the possibility of creating electric propulsion engines began in the late 50s at the IAE (under the leadership of L.A. Artsimovich), NII-1 (under the leadership of V.M. Ievlev and A.A. Porotnikov) and a number of other organizations. nizations. Thus, OKB-1 conducted research aimed at creating a nuclear electric propulsion engine. In 1962 The preliminary design of the LV N1 included “Materials on nuclear power propulsion for heavy interplanetary spacecraft.” In 1960 A government decree was issued on the organization of work on electric propulsion. In addition to IAE and NII-1, dozens of other research institutes, design bureaus and organizations were involved in the work. By 1962 At NII-1, an erosion-type pulsed plasma engine (PPD) was created. In SPD, plasma is formed due to the evaporation (ablation) of a solid dielectric (fluoroplastic-4, also known as Teflon) in a pulsed (spark) radiant energy electrical discharge lasting several microseconds (pulse power 10-200 MW) followed by electromagnetic acceleration of the plasma. The first life tests of such an engine began on March 27 and continued until April 16, 1962. With an average power consumption of 1 kW (pulse - 200 MW), the thrust was 1g. - “price” of traction 1 kW/g. For testing in space, the “price” of thrust was approximately 4 times lower. Such parameters were achieved by the end of 1962. New engine consumed 50 W (pulse power 10 MW) to create a thrust of 0.2 g. (later the “price” of traction was increased to 85W per year). In March 1963 A remote control for a spacecraft stabilization system based on IPD was created and tested, which included six motors, a voltage converter (the spark discharge was created by capacitors with a capacity of 100 μF with a voltage of 1 kV), a software switching device, high-voltage hermetic connectors and other equipment. The plasma temperature reached 30 thousand degrees. and the exhaust speed is 16 km/sec. The first launch of a spacecraft (Zond-type interplanetary station) with electric propulsion was scheduled for November 1963. Launch November 11, 1963 ended in a launch vehicle accident. Only November 30, 1964 The Zond-2 probe with an electric propulsion system on board successfully launched towards Mars. December 14, 1964 At a distance of more than 5 million km from the Earth, plasma engines were turned on (gas-dynamic engines were turned off at this time) powered by solar batteries. Within 70min. six plasma engines maintained the necessary orientation of the station in space. In the USA in 1968 The communications satellite “LES-6” was launched with four erosion IPDs, which operated for more than 2 years. according to ERD, the Fakel OKB was organized (on the basis of the B.S. Stechkin OKB in Kaliningrad). The first development of the Fakel Design Bureau was the electric propulsion system of the stabilization and orientation system for military-purpose spacecraft of the Globus type (the Horizon satellite), close to the Zond-2 IPD. Since 1971 In the orbit correction system of the Meteor meteorological satellite, two plasma engines from the Fakel Design Bureau were used, each of which, weighing 32.5 kg, consumed about 0.4 kW, while developing a thrust of about 2 g. the exhaust velocity was over 8 km/sec and the amount of RT (compressed xenon) was 2.4 kg. Since 1982 Geostationary communication satellites “Luch” use electric propulsion systems developed by OKB “Fakel”. Until 1991 Electric propulsion engines operated successfully on 16 spacecraft. More details about electric propulsion will be discussed on a separate page of the website. The thrust of the created electric propulsion engines was limited by the electrical power of the onboard energy sources. To increase the thrust of the electric propulsion system to several kilograms, it was necessary to increase the power to several hundred kilowatts, which was practically impossible using traditional methods (batteries and solar panels). Therefore, in parallel with work on electric propulsion, the IPPE, IAE and other organizations began work on the direct conversion of thermal energy of a nuclear reactor into electrical energy. The elimination of intermediate stages of energy conversion and the absence of moving parts made it possible to create compact, lightweight and reliable power plants of sufficiently high power and service life, suitable for use on spacecraft. In 1965 OKB-1, together with IPPE, developed a preliminary design of the nuclear electric propulsion engine YaERD-2200 for with the crew. The propulsion system consisted of two blocks (each had its own nuclear power plant), the electrical power of each block was 2200 kW, thrust 8.3 kg. The magnetoplasma engine had a specific impulse of about 54,000 m/sec. In 1966-70. A preliminary design of a thermionic nuclear power plant (11B97) and electric propulsion system for the Martian complex launched by the N1M launch vehicle was developed. The nuclear electric propulsion system was assembled from separate blocks; the electrical power of one block was up to 5 MW. electric propulsion thrust - 9.5 kg. with a specific thrust impulse of 78000 m/sec. However, the creation of powerful nuclear power sources took much longer than expected. The first to find practical application, due to their simplicity of design and low weight, were radioisotope thermoelectric generators (RTGs) that used the heat of spontaneous fission of radioactive isotopes (for example, polonium-210). The thermoelectric converter was essentially an ordinary thermocouple. However, their relatively low energy intensity of RTGs and the high cost of the isotopes used greatly limited their use. The use of thermoelectric and thermionic energy converters in combination with nuclear reactors combined into a single unit (converter reactor) had better prospects . To experimentally test the possibility of creating a small-sized reactor-converter, at the IEA (together with NPO Luch) in 1964. The experimental installation “Romashka” was created. The heat generated in the core heated a thermoelectric converter located on the outer surface of the reactor, consisting of a large number of silicon-germanium semiconductor wafers, while their other surface was cooled by a radiator. Electrical power was 500 W. at a reactor thermal power of 40 kW. Tests of "Romashka" were soon stopped because the BES-5 (Buk) nuclear power plant of much higher power was already being tested. The development of the BES-5 nuclear power plant with an electrical power of 2800 W, intended for power supply of the US-A radar reconnaissance spacecraft equipment, began in 1961. at the NPO "Red Star" under the scientific leadership of the IPPE. The first flight of the US-A spacecraft (October 3, 1970, “Cosmos-367”) was unsuccessful - the BES-5 nuclear power plant operated for 110 minutes. after which the reactor core melted. The next 9 launches of the modified nuclear power plant were successful in 1975. The US-A spacecraft was adopted by the Navy. In January 1978 due to the failure of the US-A spacecraft (Cosmos -954), fragments of the Buk nuclear power plant fell on Canadian territory. In total (before decommissioning in 1989), 32 launches of these spacecraft were carried out. In parallel with the work on the creation of nuclear power plants with thermoelectric wire generators - work was carried out on nuclear power plants with thermionic converters that had higher efficiency, service life and weight-size characteristics. Thermionic nuclear power plants use the effect of thermionic emission from the surface of a sufficiently heated conductor. To test high-power thermionic converters, a reactor was created in 1964. base in Kyiv (in 1970, the same base appeared in Alma-Ata). The work was carried out by two developers - the Topaz nuclear power plant with an electrical power of 5-6.6 kW was developed at NPO "Red Star" (scientific management of IPPE). - nuclear intelligence, Energovak-TsKBM (scientific management of the Russian Research Center Kurchatov Institute) developed the Yenisei nuclear power plant for the Ekran-AM television broadcasting spacecraft. The Topaz nuclear power plant was tested twice in space conditions on board the Plasma spacecraft. -A" (February 2, 1987 "Cosmos-1818" and July 10, 1987 "Cosmos-1867"). With a design life of one year, already in the second flight “Topaz” worked for more than 11 months, but the launches stopped there. Work on the Yenisei nuclear power plant was stopped at the ground testing stage due to the cessation of work on the spacecraft for which it was intended. More details about Nuclear power sources for spacecraft will be discussed on a separate page of the site. The first reactor, named KIWI-A, was tested on July 1, 1959. at a special training ground in Nevada. It was a homogeneous reactor whose core was assembled from unprotected plates consisting of a mixture of graphite and uranium-235 oxide enriched to 90%. Heavy water served as a neutron moderator. Uranium oxide could not withstand high temperatures, and hydrogen passing through the channels between the plates could only heat up to 1600 degrees. The power of these reactors was only 100 MW. The Kiwi-A tests, like all subsequent ones, were carried out with an open ejection. The activity of the exhaust products was low and practically no restrictions were introduced on work in the test area. The reactor tests were completed on December 7, 1961. (during the last launch, the core was destroyed, and fragments of plates were released into the exhaust stream). The results obtained from six “hot tests” of nuclear-powered engines turned out to be very encouraging, and at the beginning of 1961. a report was prepared on the need to test the reactor in flight. However, soon the “dizziness” from the first successes began to pass, and the understanding came that there were many problems on the way to creating a nuclear propulsion system, the solution of which would require a lot of time and money. In addition, progress in the creation of chemical engines for combat missiles has left only the space sphere for the use of nuclear propulsion engines. Despite the fact that with the arrival in White House Kennedy administration (in 1961), work on a nuclear-powered aircraft was stopped, the Rover program was called “one of the four priority areas in the conquest of space” and was further developed. New programs “Rift” (RIFT - Reactor In Flight Test) and “Nerva” (NERVA - Nuclear Engine for Rocket Vehicle Application) were adopted to create a flight version of the nuclear powered engine. Testing of the Kiwi series reactors continued. September 1, 1962 The Kiwi-V with a capacity of 1100 MW running on liquid hydrogen was tested. The uranium oxide was replaced with a more heat-resistant carbide, in addition, the rods began to be coated with niobium carbide, but during the test, when trying to reach the design temperature, the reactor began to collapse (pieces of plates began to fly out through the nozzle). The next launch took place on November 30, 1962. but after 260sec. During operation, the test was stopped due to the appearance of strong vibration inside the reactor and flashes of flame in the exhaust stream. As a result of these failures, planned for 1963. tests of the Kiwi-V reactors were postponed until next year. In August 1964 Another test was carried out during which the engine operated at a power of 900 MW for more than eight minutes, developing a thrust of 22.7 tons. at an exhaust speed of 7500 m/sec. At the very beginning of 1965. the last test was carried out during which the reactor was destroyed. It was deliberately brought to the point of explosion as a result of rapid “acceleration”. If normally the transition of a reactor from zero power to full power requires tens of seconds, then during this test the duration of such a transition was determined only by the inertia of the control rods, and approximately 44 milliseconds after they were transferred to the full power position, an explosion equivalent to 50–60 kg occurred. trinitrotoluene. experimental). Since by this time a material capable of operating at 2700–3000 degrees had not yet been found. and to resist destruction by hot hydrogen, it was decided to reduce the operating temperature and the specific impulse was limited to 8400 m/sec. Tests of the reactor began in 1964, they achieved a power of 1000 MW and a thrust of approximately 22.5 tons. exhaust velocity is more than 7000m/s. In 1966 For the first time, the engine was tested at full power of 1100 MW. On which he worked for 28 minutes. (out of 110 minutes of work). The temperature of hydrogen at the outlet of the reactor reached 2000 degrees, the thrust was 20 tons. At the next stage of the program, it was planned to use more powerful Phoebus reactors (Phoebus, and then Pewee). The development of improved solid-phase graphite reactors for the NERVA engine under the Phoebus program has been carried out at the Los Alamos Laboratory since 1963. The first of these reactors has approximately the same dimensions as the Kiwi-V (diameter 0.813 m, length 1.395 m), but is designed for approximately twice the power. On the basis of this reactor it was planned to create the NERVA-1 engine. The next modification with a power of about 4000–5000 MW was to be used for the NERVA-2 engine. This engine has a thrust in the range of 90-110t. should have had an exhaust velocity of up to 9000 m/s. Engine height is approximately 12m. outer diameter - 1.8 m. Working fluid consumption 136kg/s. The weight of the NERVA-2 engine was approximately 13.6 tons. Due to financial difficulties, the NERVA-2 engine was soon abandoned and switched to designing the NERVA-1 engine of increased power with a thrust of 34 tons. with an outflow speed of 8250 m/s. The first test of the NRX-A6 reactor for this engine was carried out on December 15, 1967. In June 1969 The first hot tests of the experimental NERVA XE engine at a thrust of 22.7 tons took place. The total engine operating time was 115 minutes, 28 starts were made. The NERVA-1 YARD had a homogeneous reactor with a core with a diameter of 1 m. and height 1.8 m. consisting of 1800 rod hexagonal fuel elements (concentration of nuclear fuel 200 - 700 mg/cub.cm.). The reactor had a ring reflector about 150 mm thick, made of beryllium oxide. The reactor power vessel is made of aluminum alloy, the internal radiation shield is made of composite material (boron carbide–aluminum–titanium hydride). Additional external protection can also be installed between the reactor and the turbopump units. NASA considered the engine suitable for the planned flight to Mars. It was supposed to be installed on the upper stage of the Saturn 5 launch vehicle. Such a carrier could carry two or three times more payload into space than its purely chemical version. But The Rift program involved the launch of a Saturn-V rocket with an experimental reactor along a ballistic trajectory to an altitude of up to 1000 km. and their subsequent fall into the southern Atlantic Ocean. Before entering the water, the nuclear reactor had to be blown up (few people thought about radiation safety at that time). But year after year the program was delayed and it was ultimately never implemented. The American space program was canceled by the Nixon administration. And it stopped in 1970. The production of Saturn-5 rockets put a final end to the program for using nuclear propulsion engines. At Los Alamos, work on Pewee engines under the Rover program continued until 1972. after which the program was finally closed. but then the funding was stopped). The development of the entire project will require 17 billion rubles. Wait and see.
Found an interesting article. In general, nuclear spaceships have always interested me. This is the future of astronautics. Extensive work on this topic was also carried out in the USSR. The article is just about them.
To space on nuclear power. Dreams and reality.
Doctor of Physical and Mathematical Sciences Yu. Ya. Stavissky
In 1950, I defended my diploma as an engineer-physicist at the Moscow Mechanical Institute (MMI) of the Ministry of Ammunition. Five years earlier, in 1945, the Faculty of Engineering and Physics was formed there, training specialists for the new industry, whose tasks mainly included the production of nuclear weapons. The faculty was second to none. Along with fundamental physics in the scope of university courses (methods of mathematical physics, theory of relativity, quantum mechanics, electrodynamics, statistical physics and others), we were taught a full range of engineering disciplines: chemistry, metallurgy, strength of materials, theory of mechanisms and machines, etc. Created by an outstanding Soviet physicist Alexander Ilyich Leypunsky, the Faculty of Engineering and Physics of MMI grew over time into the Moscow Engineering and Physics Institute (MEPhI). Another engineering and physics faculty, which also later merged with MEPhI, was formed at the Moscow Power Engineering Institute (MPEI), but if at MMI the main emphasis was on fundamental physics, then at the Energetic Institute it was on thermal and electrical physics.
We studied quantum mechanics from the book of Dmitry Ivanovich Blokhintsev. Imagine my surprise when, upon assignment, I was sent to work with him. I, an avid experimenter (as a child, I took apart all the clocks in the house), and suddenly I find myself with a famous theorist. I was seized with a slight panic, but upon arrival at the place - “Object B” of the USSR Ministry of Internal Affairs in Obninsk - I immediately realized that I was worrying in vain.
By this time, the main topic of “Object B”, which until June 1950 was actually headed by A.I. Leypunsky, has already formed. Here they created reactors with expanded reproduction of nuclear fuel - “fast breeders”. As director, Blokhintsev initiated the development of a new direction - the creation of nuclear-powered engines for space flights. Mastering space was a long-time dream of Dmitry Ivanovich; even in his youth he corresponded and met with K.E. Tsiolkovsky. I think that understanding the gigantic possibilities of nuclear energy, whose calorific value is millions of times higher than the best chemical fuels, determined the life path of D.I. Blokhintseva.
“You can’t see face to face”... In those years we didn’t understand much. Only now, when the opportunity has finally arisen to compare the deeds and destinies of the outstanding scientists of the Physics and Energy Institute (PEI) - the former “Object B”, renamed on December 31, 1966 - is a correct, as it seems to me, understanding of the ideas that motivated them at that time emerging . With all the variety of activities that the institute had to deal with, it is possible to identify priority scientific areas that were in the sphere of interests of its leading physicists.
The main interest of AIL (as Alexander Ilyich Leypunsky was called behind his back at the institute) is the development of global energy based on fast breeder reactors (nuclear reactors that have no restrictions on nuclear fuel resources). It is difficult to overestimate the importance of this truly “cosmic” problem, to which he devoted the last quarter century of his life. Leypunsky spent a lot of effort on the defense of the country, in particular on the creation of nuclear engines for submarines and heavy aircraft.
Interests D.I. Blokhintsev (he got the nickname “D.I.”) were aimed at solving the problem of using nuclear energy for space flights. Unfortunately, at the end of the 1950s, he was forced to leave this work and lead the creation of an international scientific center - the Joint Institute for Nuclear Research in Dubna. There he worked on pulsed fast reactors - IBR. This became the last big thing of his life.
One goal - one team
DI. Blokhintsev, who taught at Moscow State University in the late 1940s, noticed there and then invited the young physicist Igor Bondarenko, who was literally raving about nuclear-powered spaceships, to work in Obninsk. His first scientific supervisor was A.I. Leypunsky, and Igor, naturally, dealt with his topic - fast breeders.
Under D.I. Blokhintsev, a group of scientists formed around Bondarenko, who united to solve the problems of using atomic energy in space. In addition to Igor Ilyich Bondarenko, the group included: Viktor Yakovlevich Pupko, Edwin Aleksandrovich Stumbur and the author of these lines. The main ideologist was Igor. Edwin conducted experimental studies of ground-based models of nuclear reactors in space installations. I worked mainly on “low thrust” rocket engines (thrust in them is created by a kind of accelerator - “ion propulsion”, which is powered by energy from a space nuclear power plant). We investigated the processes
flowing in ion propulsors, on ground stands.
On Viktor Pupko (in the future
he became the head of the space technology department of the IPPE) there was a lot of organizational work. Igor Ilyich Bondarenko was an outstanding physicist. He had a keen sense of experimentation and carried out simple, elegant and very effective experiments. I think that no experimentalist, and perhaps few theorists, “felt” fundamental physics. Always responsive, open and friendly, Igor was truly the soul of the institute. To this day, the IPPE lives by his ideas. Bondarenko lived an unjustifiably short life. In 1964, at the age of 38, he died tragically due to medical error. It was as if God, seeing how much man had done, decided that it was too much and commanded: “Enough.”
One cannot help but recall another unique personality - Vladimir Aleksandrovich Malykh, a technologist “from God,” a modern Leskovsky Lefty. If the “products” of the above-mentioned scientists were mainly ideas and calculated estimates of their reality, then Malykh’s works always had an output “in metal”. Its technology sector, which at the time of the IPPE's heyday numbered more than two thousand employees, could do, without exaggeration, anything. Moreover, he himself always played the key role.
V.A. Malykh began as a laboratory assistant at the Research Institute of Nuclear Physics of Moscow State University, having completed three courses in physics; the war did not allow him to complete his studies. At the end of the 1940s, he managed to create a technology for the production of technical ceramics based on beryllium oxide, a unique dielectric material with high thermal conductivity. Before Malykh, many struggled unsuccessfully with this problem. A fuel cell based on serial of stainless steel and natural uranium, which he developed for the first nuclear power plant, is a miracle in those times and even today. Or the thermionic fuel element of the reactor-electric generator created by Malykh to power spacecraft - “garland”. Until now, nothing better has appeared in this area. Malykh’s creations were not demonstration toys, but elements of nuclear technology. They worked for months and years. Vladimir Aleksandrovich became a Doctor of Technical Sciences, laureate of the Lenin Prize, Hero of Socialist Labor. In 1964, he tragically died from the consequences of military shell shock.
Step by step
S.P. Korolev and D.I. Blokhintsev has long nurtured the dream of manned space flight. Close working ties were established between them. But in the early 1950s, at the height of the cold war“, no expense was spared only for military purposes. Rocket technology was considered only as a carrier of nuclear charges, and satellites were not even thought about. Meanwhile, Bondarenko, knowing about the latest achievements of rocket scientists, persistently advocated the creation of an artificial Earth satellite. Subsequently, no one remembered this.
The history of the creation of the rocket that lifted the planet’s first cosmonaut, Yuri Gagarin, into space is interesting. It is connected with the name of Andrei Dmitrievich Sakharov. In the late 1940s, he developed a combined fission-thermonuclear charge, the “puff,” apparently independently of the “father of the hydrogen bomb,” Edward Teller, who proposed a similar product called the “alarm clock.” However, Teller soon realized that a nuclear charge of such a design would have a “limited” power, no more than ~ 500 kilotons of ton equivalent. This is not enough for an “absolute” weapon, so the “alarm clock” was abandoned. In the Union, in 1953, Sakharov’s RDS-6s puff paste was blown up.
After successful tests and Sakharov’s election as an academician, the then head of the Ministry of Medium Machine Building V.A. Malyshev invited him to his place and set him the task of determining the parameters of the next generation bomb. Andrei Dmitrievich estimated (without detailed study) the weight of the new, much more powerful charge. Sakharov’s report formed the basis for a resolution of the CPSU Central Committee and the USSR Council of Ministers, which obliged S.P. Korolev to develop for this charge ballistic launch vehicle. It was precisely this R-7 rocket called “Vostok” that launched an artificial Earth satellite into orbit in 1957 and a spacecraft with Yuri Gagarin in 1961. There were no plans to use it as a carrier of a heavy nuclear charge, since the development of thermonuclear weapons took a different path.
At the initial stage of the space nuclear program, IPPE, together with Design Bureau V.N. Chelomeya was developing a nuclear cruise missile. This direction did not develop for long and ended with calculations and testing of engine elements created in the department of V.A. Malykha. In essence, we were talking about a low-flying unmanned aircraft with a ramjet nuclear engine and a nuclear warhead (a kind of nuclear analogue of the “buzzing bug” - the German V-1). The system was launched using conventional rocket boosters. After reaching the given speed, thrust was created atmospheric air, heated by the fission chain reaction of beryllium oxide impregnated with enriched uranium.
Generally speaking, the ability of a rocket to perform a particular astronautics task is determined by the speed it acquires after using up the entire supply of working fluid (fuel and oxidizer). It is calculated using the Tsiolkovsky formula: V = c×lnMn/ Mk, where c is the exhaust velocity of the working fluid, and Mn and Mk are the initial and final mass of the rocket. In conventional chemical rockets, the exhaust velocity is determined by the temperature in the combustion chamber, the type of fuel and oxidizer, and the molecular weight of the combustion products. For example, the Americans used hydrogen as fuel in the descent module to land astronauts on the Moon. The product of its combustion is water, whose molecular weight is relatively low, and the flow rate is 1.3 times higher than when burning kerosene. This is enough for the descent vehicle with astronauts to reach the surface of the Moon and then return them to the orbit of its artificial satellite. Korolev’s work with hydrogen fuel was suspended due to an accident with human casualties. We did not have time to create a lunar lander for humans.
One of the ways to significantly increase the exhaust rate is to create nuclear thermal rockets. For us, these were ballistic nuclear missiles (BAR) with a range of several thousand kilometers (a joint project of OKB-1 and IPPE), while for the Americans, similar systems of the “Kiwi” type were used. The engines were tested at testing sites near Semipalatinsk and Nevada. The principle of their operation is as follows: hydrogen is heated in a nuclear reactor to high temperatures, passes into the atomic state and in this form flows out of the rocket. In this case, the exhaust speed increases by more than four times compared to a chemical hydrogen rocket. The question was to find out to what temperature hydrogen could be heated in a reactor with solid fuel elements. Calculations gave about 3000°K.
At NII-1, whose scientific director was Mstislav Vsevolodovich Keldysh (then President of the USSR Academy of Sciences), the department of V.M. Ievleva, with the participation of the IPPE, was working on a completely fantastic scheme - a gas-phase reactor in which a chain reaction occurs in a gas mixture of uranium and hydrogen. Hydrogen flows out of such a reactor ten times faster than from a solid fuel reactor, while uranium is separated and remains in the core. One of the ideas involved the use of centrifugal separation, when a hot gas mixture of uranium and hydrogen is “swirled” by incoming cold hydrogen, as a result of which the uranium and hydrogen are separated, as in a centrifuge. Ievlev tried, in fact, to directly reproduce the processes in the combustion chamber of a chemical rocket, using as an energy source not the heat of fuel combustion, but the fission chain reaction. This opened the way to full use of energy intensity atomic nuclei. But the question of the possibility of pure hydrogen (without uranium) flowing out of the reactor remained unresolved, not to mention the technical problems associated with maintaining high-temperature gas mixtures at pressures of hundreds of atmospheres.
IPPE's work on ballistic nuclear missiles ended in 1969-1970 with “fire tests” at the Semipalatinsk test site of a prototype nuclear rocket engine with solid fuel elements. It was created by the IPPE in cooperation with the Voronezh Design Bureau A.D. Konopatov, Moscow Research Institute-1 and a number of other technological groups. The basis of the engine with a thrust of 3.6 tons was the IR-100 nuclear reactor with fuel elements made of a solid solution of uranium carbide and zirconium carbide. The hydrogen temperature reached 3000°K with a reactor power of ~170 MW.
Low thrust nuclear rockets
So far we have been talking about rockets with a thrust exceeding their weight, which could be launched from the surface of the Earth. In such systems, increasing the exhaust velocity makes it possible to reduce the supply of working fluid, increase the payload, and eliminate multi-stage operation. However, there are ways to achieve practically unlimited outflow velocities, for example, acceleration of matter by electromagnetic fields. I worked in this area in close contact with Igor Bondarenko for almost 15 years.
The acceleration of a rocket with an electric propulsion engine (EPE) is determined by the ratio of the specific power of the space nuclear power plant (SNPP) installed on them to the exhaust velocity. In the foreseeable future, the specific power of the KNPP, apparently, will not exceed 1 kW/kg. In this case, it is possible to create rockets with low thrust, tens and hundreds of times less than the weight of the rocket, and with very low consumption of the working fluid. Such a rocket can only launch from the orbit of an artificial Earth satellite and, slowly accelerating, reach high speeds.
For flights within the Solar System, we need rockets with an exhaust velocity of 50-500 km/s, and for flights to the stars, “photon rockets” that go beyond our imagination with an exhaust velocity equal speed Sveta. In order to carry out a long-distance space flight of any reasonable time, unimaginable power density of power plants is required. It is not yet possible to even imagine what physical processes they could be based on.
Calculations have shown that during the Great Confrontation, when the Earth and Mars are closest to each other, it is possible to fly a nuclear spacecraft with a crew to Mars in one year and return it to the orbit of an artificial Earth satellite. The total weight of such a ship is about 5 tons (including the supply of the working fluid - cesium, equal to 1.6 tons). It is determined mainly by the mass of the KNPP with a power of 5 MW, and the jet thrust is determined by a two-megawatt beam of cesium ions with an energy of 7 kiloelectronvolts *. The ship launches from the orbit of an artificial Earth satellite, enters the orbit of a Mars satellite, and will have to descend to its surface on a device with a hydrogen chemical engine, similar to the American lunar one.
This direction, based on technical solutions possible today, a large series of works was devoted to IPPE.
Ion propulsion
In those years, ways of creating various electric propulsion systems for spacecraft, such as “plasma guns”, electrostatic accelerators of “dust” or liquid droplets were discussed. However, none of the ideas had a clear physical basis. The discovery was surface ionization of cesium.
Back in the 20s of the last century, American physicist Irving Langmuir discovered the surface ionization of alkali metals. When a cesium atom evaporates from the surface of a metal (in our case, tungsten), whose electron work function is greater than the cesium ionization potential, in almost 100% of cases it loses a weakly bound electron and turns out to be a singly charged ion. Thus, the surface ionization of cesium on tungsten is the physical process that makes it possible to create an ion propulsion device with almost 100% utilization of the working fluid and with an energy efficiency close to unity.
Our colleague Stal Yakovlevich Lebedev played a major role in creating models of an ion propulsion system of this type. With his iron tenacity and perseverance, he overcame all obstacles. As a result, it was possible to reproduce a flat three-electrode ion propulsion circuit in metal. The first electrode is a tungsten plate measuring approximately 10x10 cm with a potential of +7 kV, the second is a tungsten grid with a potential of -3 kV, and the third is a thoriated tungsten grid with zero potential. The “molecular gun” produced a beam of cesium vapor, which, through all the grids, fell on the surface of the tungsten plate. A balanced and calibrated metal plate, the so-called balance, served to measure the “force,” i.e., the thrust of the ion beam.
The accelerating voltage to the first grid accelerates cesium ions to 10,000 eV, the decelerating voltage to the second grid slows them down to 7000 eV. This is the energy with which the ions must leave the thruster, which corresponds to an exhaust speed of 100 km/s. But a beam of ions, limited by the space charge, cannot “go into outer space.” The volumetric charge of the ions must be compensated by electrons to form a quasi-neutral plasma, which spreads unhindered in space and creates reactive thrust. The source of electrons to compensate for the volume charge of the ion beam is the third grid (cathode) heated by current. The second, “blocking” grid prevents electrons from getting from the cathode to the tungsten plate.
The first experience with the ion propulsion model marked the beginning of more than ten years of work. One of the latest models, with a porous tungsten emitter, created in 1965, produced a “thrust” of about 20 g at an ion beam current of 20 A, had an energy utilization rate of about 90% and matter utilization of 95%.
Direct conversion of nuclear heat into electricity
Ways to directly convert nuclear fission energy into electrical energy have not yet been found. We still can't do without intermediate- heat engine. Since its efficiency is always less than one, the “waste” heat needs to be put somewhere. There are no problems with this on land, in water or in the air. In space, there is only one way - thermal radiation. Thus, KNPP cannot do without a “refrigerator-emitter”. The radiation density is proportional to the fourth power of absolute temperature, so the temperature of the radiating refrigerator should be as high as possible. Then it will be possible to reduce the area of the radiating surface and, accordingly, the mass of the power plant. We came up with the idea of using “direct” conversion of nuclear heat into electricity, without a turbine or generator, which seemed more reliable for long-term operation at high temperatures.
From the literature we knew about the works of A.F. Ioffe - the founder of the Soviet school of technical physics, a pioneer in the research of semiconductors in the USSR. Few people now remember the current sources he developed, which were used during the Great Patriotic War. Patriotic War. At that time, more than one partisan detachment had contact with the mainland thanks to “kerosene” TEGs - Ioffe thermoelectric generators. A “crown” made of TEGs (it was a set of semiconductor elements) was put on a kerosene lamp, and its wires were connected to radio equipment. The “hot” ends of the elements were heated by the flame of a kerosene lamp, the “cold” ends were cooled in air. The heat flow, passing through the semiconductor, generated an electromotive force, which was enough for a communication session, and in the intervals between them the TEG charged the battery. When, ten years after the Victory, we visited the Moscow TEG plant, it turned out that they were still being sold. Many villagers then had economical Rodina radios with direct-heat lamps, powered by a battery. TAGs were often used instead.
The problem with kerosene TEG is its low efficiency (only about 3.5%) and low maximum temperature (350°K). But the simplicity and reliability of these devices attracted developers. Thus, semiconductor converters developed by the group of I.G. Gverdtsiteli at the Sukhumi Institute of Physics and Technology, found application in space installations of the Buk type.
At one time A.F. Ioffe proposed another thermionic converter - a diode in a vacuum. The principle of its operation is as follows: the heated cathode emits electrons, some of them, overcoming the potential of the anode, do work. A significantly higher efficiency (20-25%) was expected from this device at operating temperature above 1000°K. In addition, unlike a semiconductor, a vacuum diode is not afraid of neutron radiation, and it can be combined with a nuclear reactor. However, it turned out that it was impossible to implement the idea of a “vacuum” Ioffe converter. As in an ion propulsion device, in a vacuum converter you need to get rid of the space charge, but this time not ions, but electrons. A.F. Ioffe intended to use micron gaps between the cathode and anode in a vacuum converter, which is practically impossible under conditions of high temperatures and thermal deformations. This is where cesium comes in handy: one cesium ion produced by surface ionization at the cathode compensates for the space charge of about 500 electrons! In essence, a cesium converter is a “reversed” ion propulsion device. Physical processes they are close.
“Garlands” by V.A. Malykha
One of the results of IPPE's work on thermionic converters was the creation of V.A. Malykh and serial production in his department of fuel elements from series-connected thermionic converters - “garlands” for the Topaz reactor. They provided up to 30 V - a hundred times more than single-element converters created by “competing organizations” - the Leningrad group M.B. Barabash and later - the Institute of Atomic Energy. This made it possible to “remove” tens and hundreds of times more power from the reactor. However, the reliability of the system, stuffed with thousands of thermionic elements, raised concerns. At the same time, steam and gas turbine units worked without failures, so we also paid attention to the “machine” conversion of nuclear heat into electricity.
The whole difficulty lay in the resource, because in long-distance space flights, turbogenerators must operate for a year, two, or even several years. To reduce wear, the “revolutions” (turbine rotation speed) should be made as low as possible. On the other hand, a turbine operates efficiently if the speed of the gas or steam molecules is close to the speed of its blades. Therefore, first we considered the use of the heaviest - mercury steam. But we were frightened by the intense radiation-stimulated corrosion of iron and stainless steel that occurred in a mercury-cooled nuclear reactor. In two weeks, corrosion “ate” the fuel elements of the experimental fast reactor “Clementine” at the Argonne Laboratory (USA, 1949) and the BR-2 reactor at the IPPE (USSR, Obninsk, 1956).
Potassium vapor turned out to be tempting. The reactor with potassium boiling in it formed the basis of the power plant we were developing for a low-thrust spacecraft - potassium steam rotated the turbogenerator. This “machine” method of converting heat into electricity made it possible to count on an efficiency of up to 40%, while real thermionic installations provided an efficiency of only about 7%. However, KNPP with “machine” conversion of nuclear heat into electricity was not developed. The matter ended with the release of a detailed report, essentially a “physical note” to the technical design of a low-thrust spacecraft for a crewed flight to Mars. The project itself was never developed.
Later, I think, interest in space flights using nuclear rocket engines simply disappeared. After the death of Sergei Pavlovich Korolev, support for IPPE’s work on ion propulsion and “machine” nuclear power plants noticeably weakened. OKB-1 was headed by Valentin Petrovich Glushko, who had no interest in bold, promising projects. The Energia Design Bureau, which he created, built powerful chemical rockets and the Buran spacecraft returning to Earth.
"Buk" and "Topaz" on the satellites of the "Cosmos" series
Work on the creation of KNPP with direct conversion of heat into electricity, now as power sources for powerful radio satellites (space radar stations and television broadcasters), continued until the start of perestroika. From 1970 to 1988, about 30 radar satellites were launched into space with Buk nuclear power plants with semiconductor converter reactors and two with Topaz thermionic plants. The Buk, in fact, was a TEG - a semiconductor Ioffe converter, but instead of a kerosene lamp it used a nuclear reactor. It was a fast reactor with a power of up to 100 kW. The full load of highly enriched uranium was about 30 kg. Heat from the core was transferred by liquid metal - a eutectic alloy of sodium and potassium - to semiconductor batteries. Electric power reached 5 kW.
The Buk installation, under the scientific guidance of the IPPE, was developed by OKB-670 specialists M.M. Bondaryuk, later - NPO "Red Star" (chief designer - G.M. Gryaznov). The Dnepropetrovsk Yuzhmash Design Bureau (chief designer - M.K. Yangel) was tasked with creating a launch vehicle to launch the satellite into orbit.
The operating time of “Buk” is 1-3 months. If the installation failed, the satellite was transferred to a long-term orbit at an altitude of 1000 km. Over almost 20 years of launches, there were three cases of a satellite falling to Earth: two in the ocean and one on land, in Canada, in the vicinity of Great Slave Lake. Kosmos-954, launched on January 24, 1978, fell there. He worked for 3.5 months. The satellite's uranium elements burned completely in the atmosphere. Only the remains of a beryllium reflector and semiconductor batteries were found on the ground. (All this data is presented in the joint report of the US and Canadian atomic commissions on Operation Morning Light.)
The Topaz thermionic nuclear power plant used a thermal reactor with a power of up to 150 kW. The full load of uranium was about 12 kg - significantly less than that of the Buk. The basis of the reactor were fuel elements - “garlands”, developed and manufactured by Malykh’s group. They consisted of a chain of thermoelements: the cathode was a “thimble” made of tungsten or molybdenum, filled with uranium oxide, the anode was a thin-walled tube of niobium, cooled by liquid sodium-potassium. The cathode temperature reached 1650°C. The electrical power of the installation reached 10 kW.
The first flight model, the Cosmos-1818 satellite with the Topaz installation, entered orbit on February 2, 1987 and operated flawlessly for six months until cesium reserves were exhausted. The second satellite, Cosmos-1876, was launched a year later. He worked in orbit almost twice as long. The main developer of Topaz was the MMZ Soyuz Design Bureau, headed by S.K. Tumansky (former design bureau of aircraft engine designer A.A. Mikulin).
This was in the late 1950s, when we were working on ion propulsion, and he was working on the third stage engine for a rocket that would fly around the Moon and land on it. Memories of Melnikov’s laboratory are still fresh to this day. It was located in Podlipki (now the city of Korolev), on site No. 3 of OKB-1. A huge workshop with an area of about 3000 m2, lined with dozens of desks with daisy chain oscilloscopes recording on 100 mm roll paper (this was a bygone era; today one personal computer would be enough). At the front wall of the workshop there is a stand where the combustion chamber of the “lunar” rocket engine is mounted. Oscilloscopes have thousands of wires from sensors for gas velocity, pressure, temperature and other parameters. The day begins at 9.00 with the ignition of the engine. It runs for several minutes, then immediately after stopping, a team of first-shift mechanics disassembles it, carefully inspects and measures the combustion chamber. At the same time, oscilloscope tapes are analyzed and recommendations for design changes are made. Second shift - designers and workshop workers make recommended changes. During the third shift, a new combustion chamber and diagnostic system are installed at the stand. A day later, at exactly 9.00 am, the next session. And so on without days off for weeks, months. More than 300 engine options per year!
This is how chemical rocket engines were created, which had to work for only 20-30 minutes. What can we say about testing and modifications of nuclear power plants - the calculation was that they should work for more than one year. This required truly gigantic efforts.
A nuclear rocket engine is a rocket engine whose operating principle is based on a nuclear reaction or radioactive decay, which releases energy that heats the working fluid, which can be reaction products or some other substance, such as hydrogen.
Let's look at the options and principles from action...
There are several types of rocket engines that use the principle of operation described above: nuclear, radioisotope, thermonuclear. Using nuclear rocket engines, it is possible to obtain specific impulse values significantly higher than those that can be achieved by chemical rocket engines. The high value of the specific impulse is explained by the high speed of outflow of the working fluid - about 8-50 km/s. The thrust force of a nuclear engine is comparable to that of chemical engines, which will make it possible in the future to replace all chemical engines with nuclear ones.
The main obstacle to complete replacement is the radioactive pollution caused by nuclear rocket engines.
They are divided into two types - solid and gas phase. In the first type of engines, fissile material is placed in rod assemblies with a developed surface. This makes it possible to effectively heat a gaseous working fluid, usually hydrogen acts as a working fluid. Flow rate is limited maximum temperature working fluid, which, in turn, directly depends on the maximum permissible temperature structural elements, and it does not exceed 3000 K. In gas-phase nuclear rocket engines, fissile matter is in gaseous state. Its retention in the working area is carried out through the influence of an electromagnetic field. For this type of nuclear rocket engines, the structural elements are not a limiting factor, so the exhaust speed of the working fluid can exceed 30 km/s. They can be used as first stage engines, despite the leakage of fissile material.
In the 70s XX century In the USA and the Soviet Union, nuclear rocket engines with fissile matter in the solid phase were actively tested. In the United States, a program was being developed to create an experimental nuclear rocket engine as part of the NERVA program.
The Americans developed a graphite reactor cooled by liquid hydrogen, which was heated, evaporated and ejected through a rocket nozzle. The choice of graphite was due to its temperature resistance. According to this project, the specific impulse of the resulting engine should have been twice as high as the corresponding figure characteristic of chemical engines, with a thrust of 1100 kN. The Nerva reactor was supposed to work as part of the third stage of the Saturn V launch vehicle, but due to the closure of the lunar program and the lack of other tasks for rocket engines of this class, the reactor was never tested in practice.
A gas-phase nuclear rocket engine is currently in the theoretical development stage. A gas-phase nuclear engine involves using plutonium, whose slow-moving gas stream is surrounded by a faster flow of cooling hydrogen. On orbital space stations MIR and ISS conducted experiments that could give impetus to the further development of gas-phase engines.
Today we can say that Russia has slightly “frozen” its research in the field of nuclear propulsion systems. The work of Russian scientists is more focused on the development and improvement of basic components and assemblies of nuclear power plants, as well as their unification. The priority direction for further research in this area is the creation of nuclear power propulsion systems capable of operating in two modes. The first is the nuclear rocket engine mode, and the second is the installation mode of generating electricity to power the equipment installed on board the spacecraft.
