Nuclear engines for spacecraft
Russia was still the leader in the field ofnuclear space energy. The experience of designing, building, launching and operating space vehicles equipped with a nuclear power source is provided by organizations such as RSC Energia and Roskosmos. The nuclear engine makes it possible to operate aircraft for many years, repeatedly increasing their practical usefulness.
The use of nuclear power in spaceceased to be fiction in the 70's of the last century. The first nuclear engines in 1970-1988 were launched into space and successfully operated on the spacecraft (spacecraft) "US-A". They used a system with a thermoelectric nuclear power plant (NPP) "Buk" electric power of 3 kW.
In 1987-1988 two apparatuses "Plasma-A" withthermoemission nuclear power plant "Topaz" with a capacity of 5 kW passed the space flight tests, during which the first time the power of the electric propulsion system (ERA) was supplied from a nuclear power source.
A complex of terrestrial nuclear powertests of thermionic nuclear installation "Enisei" with a capacity of 5 kW. Based on these technologies, projects of thermionic nuclear power units with a power of 25-100 kW have been developed.
RSC Energia in the 70's startedscientific and practical research, the purpose of which was to create a powerful nuclear space engine for the interorbital tug (MB) "Hercules". The work allowed to make a reserve for many years in part of the nuclear electric propulsion system (JAERDU) with a thermionic nuclear power plant with a power of several hundreds of kilowatts and electric propulsion engines with a unit power of tens and hundreds of kilowatts.
Design parameters of MB "Hercules":
- useful electric power of nuclear power plant - 550 kW;
- the specific impulse of the ERDU is 30 km / s;
- The thrust of the ERDU is 26 N;
- resource of nuclear power plants and electric power plants - 16 000 h;
- the working medium of the ERDU is xenon;
- weight (dry) of the tug - 14.5-15.7 tons, including nuclear power plants - 6.9 tons.
The newest time
In the 21st century, it is time to create a new nuclearthe engine for space. In October 2009, at a meeting of the Commission under the President of the Russian Federation on Modernization and Technological Development of the Russian Economy, a new Russian project, "Creation of a transport and energy module using a nuclear power engine of a megawatt class" was officially approved. The main developers are:
- Reactor installation - JSC "NIKIET".
- Nuclear power plant with gas turbinescheme of energy conversion, ERDU based on ionic electric propulsion engines and YaREDU as a whole - SSC " MV Keldysh ", which is also the responsible organization for the program of development of the transport-energy module (TEM) as a whole.
- RSC Energia as the general designer of the TEM should develop an automatic device with this module.
Characteristics of the new installation
New nuclear engine for space Russiaplans to launch into commercial operation in the coming years. The assumed characteristics of the gas turbine YERDU are as follows. The reactor is a gas-cooled fast neutron reactor, the temperature of the working fluid (mixture He / Xe) in front of the turbine is 1500 K, the conversion efficiency of thermal to electric energy is 35%, the type of radiator-emitter is drip. The weight of the power unit (reactor, radiation protection and conversion system, but without radiator-radiator) is 6 800 kg.
Space nuclear engines (NPP, NPP together with ERDU) are planned to be used:
- As part of future space vehicles.
- As sources of electricity for energy-intensive complexes and spacecraft.
- To solve the first two problems intransport and energy module to provide for the electron-rocket delivery of heavy spacecraft and vehicles to operational orbits and further long-term power supply of their equipment.
Principle of operation of a nuclear engine
It is based either on the synthesis of nuclei, or onuse of nuclear fission energy to form reactive thrust. There are installations of pulsed-explosive and liquid types. The explosive device throws out miniature atomic bombs into space, which are detonated at a distance of several meters, and the blast wave pushes the ship forward. In practice, such devices are not yet used.
Liquid-fueled nuclear engines, by contrast, have longdeveloped and tested. Back in the 1960s, Soviet specialists constructed a workable model RD-0410. Similar systems were developed in the USA. Their principle is based on heating the liquid by a nuclear mini-reactor, it turns into steam and forms a jet stream, which pushes the spacecraft. Although the device is called liquid, as a working medium, as a rule, hydrogen is used. Another designation of nuclear space installations is the power supply of the onboard network (instruments) of ships and satellites.
Heavy telecommunications apparatus of global space communications
At the moment, work is underway on the nuclearengine for space, which is planned to be used in heavy space communication devices. RSC Energia carried out research and design development of the global space communications system economically competitive with cheap cellular communication, which was supposed to be achieved by transferring the "telephone exchange" from Earth to space.
Prerequisites for their creation are:
- practically full filling of the geostationary orbit (GSO) by operating and passive satellites;
- exhaustion of the frequency resource;
- positive experience in the creation and commercial use of information geostationary satellites of the Yamal series.
When creating the Yamal platform, new technical solutions accounted for 95%, which allowed such devices to become competitive on the world market of space services.
It is supposed to replace modules with technologicalconnected equipment about every seven years. This would make it possible to create systems of 3-4 heavy-duty multifunctional satellites in GSO with an increase in the electric power they consume. Initially, spacecraft based on solar batteries with a capacity of 30-80 kW were designed. At the next stage, 400 kW nuclear engines with a resource of up to one year in transport mode (for delivery of the basic module to GSO) and 150-180 kW in the long-term operation mode (not less than 10-15 years) are planned to be used as an electric power source.
Nuclear engines in the system of antimeteoritic protection of the Earth
Completed by RSC Energia in the late 90's designedstudies have shown that in the creation of an antimeteoritic system for protecting the Earth from the nuclei of comets and asteroids, nuclear electrical installations and nuclear weapons can be used for:
- Creation of a monitoring system for trajectoriesAsteroids and comets crossing the Earth's orbit. For this purpose, it is proposed to arrange special spacecraft equipped with optical and radar equipment for detecting dangerous objects, calculating the parameters of their trajectories and the initial study of their characteristics. A nuclear space engine with a dual-mode thermionic nuclear power plant with capacities from 150 kW can be used in the system. Its resource must be at least 10 years old.
- Tests of means of influence (explosionthermonuclear device) on the polygon safe asteroid. The power of the NERDU for the delivery of a test device to an asteroid-polygon depends on the mass of the delivered payload (150-500 kW).
- Delivery of standard means of influence(interceptor with a total mass of 15-50 tons) to the dangerous object approaching the Earth. A nuclear jet engine with a capacity of 1-10 MW will be required to deliver a thermonuclear charge to a dangerous asteroid, the surface explosion of which due to a jet of asteroid material will be able to divert it from a dangerous trajectory.
Delivery of research equipment to the outer space
Delivery of scientific equipment to spaceobjects (distant planets, periodic comets, asteroids) can be carried out using space-based stages based on LPRE. It is advisable to use nuclear engines for space vehicles when the task is to enter the orbit of a satellite of the celestial body, direct contact with the celestial body, sampling substances and other studies that require increasing the mass of the research complex, including landing and take-off stages.
Nuclear engine for spacecraftresearch complex will expand the "start window" (due to the controlled rate of flow of the working fluid), which simplifies planning and reduces the project cost. Research carried out by RSC Energia showed that the 150 kW YaRDU with a lifetime of up to three years is a promising means of delivering space modules to the asteroid belt.
At the same time, the delivery of researchdevice into the orbits of the distant planets of the solar system requires an increase in the life of such a nuclear installation to 5-7 years. It has been proved that a complex with a nuclear power plant with a capacity of about 1 MW as part of a research spacecraft will allow accelerated delivery to orbits of artificial satellites of the most remote planets, planet-carriers to the surface of natural satellites of these planets and ground delivery from comets, asteroids, Mercury and the satellites of Jupiter and Saturn.
Reusable Tug (MB)
One of the most important ways to improveefficiency of transport operations in space is the reusable use of elements of the transport system. A nuclear engine for spacecraft with a capacity of at least 500 kW allows the creation of a reusable tug and thereby significantly increases the efficiency of the multi-link space transportation system. Particularly useful is such a system in the program for ensuring large annual cargo flows. An example can be a program to develop the moon with the creation and maintenance of a constantly growing habitable base and experimental technological and production complexes.
Calculation of turnover
According to the project studies of RSC Energia,the construction of a base on the surface of the Moon should be delivered modules with a mass of the order of 10 tons, or the moon's orbit - up to 30 tons. The total cargo flow from the Earth during the construction of an inhabited lunar base and the visited lunar orbital station is estimated at 700-800 tons, and the annual freight flow for operation and development bases - 400-500 tons.
However, the principle of the nuclear engine is notallows you to disperse transporter quickly enough. Due to the long transportation time and, accordingly, the considerable time of finding the payload in the radiation belts of the Earth, not all cargoes can be delivered using tugs with a nuclear engine. Therefore, the cargo flow, which can be provided on the basis of the YERDA, is estimated at only 100-300 tons / year.
As a criterion of economic efficiencyof the interorbital transport system, it is expedient to use the value of the unit cost of transporting a unit of payload weight (GHG) from the Earth's surface to the target orbit. RSC Energia developed an economic-mathematical model that takes into account the main components of costs in the transport system:
- for the creation and launching of the tug modules;
- for the purchase of a working nuclear installation;
- operational costs, as well as the costs of R & D and possible capital costs.
The cost indicators depend on the optimalparameters MB. Using this model, the comparative economic efficiency of the use of a reusable tugboat on the basis of a YaRDU with a capacity of 1 MW and a disposable tug based on advanced liquid-fuel rocket engines was studied in the program for providing 100 km of useful cargo with a total mass of 100 tons per year from the Earth to the Moon's orbit. When using the same carrier rocket with the carrying capacity equal to the carrying capacity of the Proton-M LV and the two-start scheme for constructing the transport system, the specific cost of delivering a unit of payload by a tugboat based on a nuclear engine will be three times lower than when using a single- tugs based on missiles with liquid engines such as DM-3.
Effective nuclear engine for spacecontributes to the solution of the Earth's environmental problems, the flight of man to Mars, the creation of a system for wireless energy transfer in space, the realization with the increased safety of dumping in the outer space of especially dangerous radioactive waste from ground nuclear power engineering, the creation of an inhabited lunar base and the beginning of industrial development of the Moon, to protect the Earth from asteroid- comet danger.