Nuclear engines for spacecraft

Russia was and still is the leader in the field of nuclear 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.

Historical Chronicle

The use of nuclear power in space has ceased to be fiction in the 70s of the last century. The first nuclear engines in 1970-1988 were launched into space and successfully operated on spacecraft (SC) "US-A". They used a system with a thermoelectric nuclear power plant (NPP) "Buk" electric power of 3 kW.

In 1987-1988, two "Plasma-A" devices with a thermoemission nuclear power plant "Topaz" with a power of 5 kW passed the space flight tests, during which the first power was supplied from the nuclear power source.

A complex of terrestrial nuclear power tests was performed with a 5-kW thermoemission nuclear facility "Yenisei". Based on these technologies, projects of thermionic nuclear power units with a power of 25-100 kW have been developed.

MB "Hercules"

RSC Energia started scientific and practical research in the 1970s, the goal of which was to create a powerful nuclear space engine for the inter-orbital 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 hundred 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;
• The mass (dry) of the tugboat is 14.5-15.7 tons, including the nuclear power plant - 6.9 tons.

The newest time

In the 21st century, it is time to create a new nuclear 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 turbine power conversion scheme, ERDU based on ionic electric propulsion engines and YaREDU as a whole - SSC " MV Keldysh ", which is also the responsible organization for the program for the 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

A new nuclear engine for space Russia plans to launch into commercial operation in the coming years. The expected 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 the thermal energy into electric energy is 35%, the type of the 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 tasks in the transport and energy module to provide for the electric-rocket delivery of heavy spacecraft and vehicles to the working orbits and further long-term power supply of their equipment.

Principle of operation of the nuclear engine

It is based either on the synthesis of nuclei or on the use of nuclear fission energy to form reactive thrust. There are installations of pulsed-explosive and liquid types. The explosive device throws 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 nuclear engines, on the other hand, have long been developed 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 with 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 electrical on-board network (instruments) of ships and satellites.

Heavy telecommunication apparatus of global space communication

At the moment, work is underway on a nuclear engine 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 communication 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 planned to replace modules with technological communication equipment about every seven years. This would allow the creation of 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 power 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 a source of electricity.

Nuclear engines in the system of antimeteoritic protection of the Earth

Completed by RSC Energia in the late 1990s, design studies have shown that in the creation of an antimeteoritic system for protecting the Earth from cometary nuclei and asteroids, nuclear power plants and nuclear power plants can be used for:

1. Creation of a monitoring system for trajectories of asteroids 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. In the system, a nuclear space engine with a dual-mode thermionic nuclear power plant with capacities from 150 kW can be used. Its resource must be at least 10 years old.
2. Tests of means of influence (explosion of a thermonuclear device) on a proving safe asteroid. The power of the NERDU for the delivery of the test device to the asteroid-polygon depends on the mass of the delivered payload (150-500 kW).
3. Deliveries of regular means of action (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, a 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

The delivery of scientific equipment to space objects (far-away planets, periodic comets, asteroids) can be carried out using space-based stages based on LPRE. The use of nuclear engines for space vehicles is advisable 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.

Engine parameters

The nuclear engine for the spaceships of the research complex will expand the "launch window" (due to the controlled rate of flow of the working fluid), which simplifies planning and reduces the price of the project. Research carried out by RSC Energia showed that the 150 kW YaRDU with a life of up to three years is a promising means of delivering space modules to the asteroid belt.

At the same time, the delivery of the research apparatus to 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 is proved that a complex with a nuclear power capacity of 1 MW as part of a research satellite will allow accelerated delivery for 5-7 years to orbits of artificial satellites of the most remote planets, planets to the surface of natural satellites of these planets, and delivery to Earth of soil from comets, asteroids, Mercury and The satellites of Jupiter and Saturn.

Reusable Tug (MB)

One of the most important ways to improve the efficiency of transport operations in space is the multiple use of the 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. Especially useful is such a system in the program for ensuring large annual cargo flows. An example is the program for developing the Moon with the creation and maintenance of a permanently growing habitable base and experimental technological and production complexes.

Calculation of turnover

According to the design studies of the RSC Energia, when building a base on the surface of the moon, modules with a mass of about 10 tons should be delivered, or up to 30 tons of the moon's orbit. The total cargo traffic from the Earth during the construction of the inhabited lunar base and the visited lunar orbital station is estimated at 700-800 tons , And the annual freight flow for the operation and development of the base is 400-500 tons.

However, the principle of operation of a nuclear engine does not allow dispatching the transport vehicle fast enough. Due to the long transportation time and, accordingly, the considerable time of finding the payload in the Earth's radiation belts, 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 per year.

Economic efficiency

As a criterion of economic efficiency of 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 costs for R & D and possible capital costs.

The cost indicators depend on the optimal MB parameters. Using this model, the comparative cost-effectiveness of using 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 to ensure the delivery from the Earth to the Moon's orbit with a height of 100 km of payload with a total mass of 100 tons / year. When using the same carrier rocket with a load-carrying capacity equal to that of the Proton-M LV and a two-start scheme for constructing the transport system, the specific cost of delivering a payload unit 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.

Conclusion

An efficient nuclear engine for space contributes to the solution of the Earth's environmental problems, the flight of man to Mars, the creation of a wireless energy transmission system in space, the implementation of the highly dangerous disposal of highly hazardous radioactive waste from terrestrial nuclear power in outer space, the creation of an inhabited lunar base and the start of industrial development of the Moon, Protection of the Earth from an asteroid-comet hazard.