Nuclear engines for spacecraft

2024 Author: Howard Calhoun | [email protected]. Last modified: 2023-12-17 10:16

Russia has been and still remains a leader in the field of nuclear space energy. Organizations such as RSC Energia and Roskosmos have experience in designing, building, launching and operating spacecraft equipped with a nuclear power source. A nuclear engine makes it possible to operate aircraft for many years, increasing their practical suitability many times over.

Historical record

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

In 1987-1988, two Plasma-A vehicles with a 5 kW Topaz thermionic nuclear power plant underwent flight and space tests, during which electric rocket engines (EP) were powered from a nuclear energy source for the first time.

Completed a complex of ground-based nuclearenergy tests of the thermionic nuclear installation "Yenisei" with a capacity of 5 kW. On the basis of these technologies, projects of thermionic nuclear power plants with a capacity of 25-100 kW have been developed.

MB Hercules

RSC Energia in the 70s started scientific and practical research, the purpose of which was to create a powerful nuclear space engine for the interorbital tug (MB) Hercules. The work made it possible to make a reserve for many years in terms of a nuclear electric propulsion system (NEP) with a thermionic nuclear power plant with a power of several to hundreds of kilowatts and electric rocket engines with a unit power of tens and hundreds of kilowatts.

Design parameters of MB "Hercules":

• net electric power of nuclear power plant – 550 kW;
• specific impulse of EPS – 30 km/s;
• projector thrust – 26 N;
• resource of nuclear power plant and electric propulsion - 16,000 hours;
• working body of EPS – xenon;
• weight (dry) of the tug - 14.5-15.7 tons, including nuclear power plants - 6.9 tons.

Recent Times

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 for the modernization and technological development of the Russian economy, a new Russian project "Creation of a transport and energy module using a megawatt-class nuclear power plant" was officially approved. Lead developers are:

• Reactor plant – OJSC NIKIET.
• Nuclear power plant with a gas turbine energy conversion scheme, EPSon the basis of ion electric rocket engines and nuclear propulsion systems as a whole - State Scientific Center “Research Center named after A. I. M. V. Keldysh”, which is also the responsible organization for the development program of the transport and energy module (TEM) as a whole.
• RKK Energia as the general designer of TEM should develop an automatic vehicle with this module.

Characteristics of the new installation

New nuclear engine for space Russia plans to put into commercial operation in the coming years. The expected characteristics of the gas turbine NEP are as follows. As a reactor, a gas-cooled fast neutron reactor is used, the temperature of the working fluid (He/Xe mixture) in front of the turbine is 1500 K, the efficiency of converting thermal into electrical energy is 35%, the type of cooler-radiator is drip. The mass of the power unit (reactor, radiation protection and conversion system, but without the radiator-radiator) is 6,800 kg.

Space nuclear engines (NPP, NPP together with EP) 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 ensure the electric rocket delivery of heavy spacecraft and vehicles to working orbits and further long-term power supply to their equipment.

The principle of operation of nuclearengine

Based either on the fusion of nuclei, or on the use of fission energy of nuclear fuel to form jet thrust. There are installations of pulse-explosive and liquid types. The explosive installation throws miniature atomic bombs into space, which, detonating at a distance of several meters, push the ship forward with an explosive wave. In practice, such devices are not yet used.

Liquid-fueled nuclear engines, on the other hand, have long been developed and tested. Back in the 60s, Soviet specialists designed a workable model RD-0410. Similar systems have been developed in the United States. 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, hydrogen is usually used as the working fluid. Another purpose of nuclear space installations is to power the electrical onboard network (instruments) of ships and satellites.

Heavy telecommunications vehicles for global space communications

At the moment, work is underway on a nuclear engine for space, which is planned to be used in heavy space communication vehicles. RSC Energia carried out research and design development of an economically competitive global space communications system with cheap cellular communications, which was supposed to be achieved by transferring the "telephone station" from Earth to space.

The prerequisites for their creation are:

• almost complete filling of the geostationary orbit (GSO) with working andpassive companions;
• frequency exhaustion;
• 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 vehicles to become competitive in the global space services market.

It is expected to replace modules with technological communications equipment approximately every seven years. This would make it possible to create systems of 3-4 heavy multifunctional GEO satellites with an increase in the electric power consumed by them. Initially, spacecraft were designed based on solar panels with a capacity of 30-80 kW. At the next stage, it is planned to use 400 kW nuclear engines with a resource of up to one year in the transport mode (for the delivery of the base module to the GSO) and 150-180 kW in the long-term operation mode (at least 10-15 years) as a source of electricity.

Nuclear engines in the Earth's anti-meteorite protection system

The design studies carried out by RSC Energia in the late 90s showed that in the creation of an anti-meteorite system for protecting the Earth from the nuclei of comets and asteroids, nuclear-electric installations and nuclear propulsion systems can be used for:

1. Creating a system for monitoring the trajectories of asteroids and comets crossing the Earth's orbit. To do this, it is proposed to place special spacecraft equipped with optical and radar equipment for detecting dangerous objects,calculation of the parameters of their trajectories and primary study of their characteristics. The system can use a nuclear space engine with a dual-mode thermionic nuclear power plant with a power of 150 kW or more. Its resource must be at least 10 years old.
2. Testing means of influence (explosion of a thermonuclear device) on a polygon safe asteroid. The power of the NEP to deliver the test device to the asteroid test site depends on the mass of the delivered payload (150-500 kW).
3. Delivery of regular means of influence (interceptor with a total weight of 15-50 tons) to a 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 the jet stream of the asteroid material, can deflect it from a dangerous trajectory.

Delivery of research equipment to deep space

Delivery of scientific equipment to space objects (distant planets, periodic comets, asteroids) can be carried out using space stages based on LRE. It is advisable to use nuclear engines for spacecraft when the task is to enter the orbit of a satellite of a celestial body, direct contact with a celestial body, sampling substances and other studies that require an increase in the mass of the research complex, the inclusion of landing and take-off stages.

Motor parameters

Nuclear engine for spacecraftThe research complex will expand the "start window" (due to the controlled outflow rate of the working fluid), which simplifies planning and reduces the cost of the project. Research carried out by RSC Energia showed that a 150 kW nuclear propulsion system with a service 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 a research apparatus to the orbits of distant planets of the solar system requires an increase in the resource of such a nuclear installation up to 5-7 years. It has been proved that a complex with a nuclear propulsion system with a power of about 1 MW as part of a research spacecraft will allow for accelerated delivery of artificial satellites of the most distant planets, planetary rovers to the surface of natural satellites of these planets and delivery of soil from comets, asteroids, Mercury and moons of Jupiter and Saturn.

Reusable tug (MB)

One of the most important ways to increase the efficiency of transport operations in space is the reusable use of elements of the transport system. A nuclear engine for spacecraft with a power of at least 500 kW makes it possible to create a reusable tug and thereby significantly increase the efficiency of a multi-link space transport system. Such a system is especially useful in a program to ensure large annual cargo flows. An example is the Moon exploration program with the creation and maintenance of a constantly growing habitable base and experimental technological and production complexes.

Calculation of cargo turnover

According to RKK design studies"Energia", during the construction of the base, modules weighing about 10 tons should be delivered to the surface of the Moon, up to 30 tons into the orbit of the Moon. to ensure the functioning and development of the base - 400-500 t.

However, the principle of operation of a nuclear engine does not allow to disperse the transporter quickly enough. Due to the long time of transportation and, accordingly, the significant time spent by the payload in the radiation belts of the Earth, not all cargo can be delivered using nuclear-powered tugs. Therefore, the cargo flow that can be provided on the basis of NEP is estimated at only 100-300 tons/year.

Cost efficiency

As a criterion for the economic efficiency of the interorbital transport system, it is advisable to use the value of the unit cost of transporting a unit mass of payload (PG) from the Earth's surface to the target orbit. RSC Energia developed an economic and mathematical model that takes into account the main cost components in the transport system:

• to create and launch tug modules into orbit;
• for the purchase of a working nuclear installation;
• operating costs, as well as R&D costs and possible capital costs.

Cost indicators depend on the optimal parameters of the MB. Using this model, a comparativeeconomic efficiency of using a reusable tug based on NEP with a power of about 1 MW and a disposable tug based on advanced liquid rocket engines in the program for delivering a payload with a total mass of 100 t/year from the Earth to the Moon's orbit with a height of 100 km. When using the same launch vehicle with a carrying capacity equal to the carrying capacity of the Proton-M launch vehicle and a two-launch scheme for constructing a transport system, the unit cost of delivering a unit mass of payload using a nuclear-powered tug will be three times lower than when using disposable tugs based on rockets with liquid engines type DM-3.

Conclusion

An efficient nuclear engine for space contributes to solving the environmental problems of the Earth, manned flight to Mars, creating a wireless power transmission system in space, implementing with increased safety the disposal of especially dangerous radioactive waste of ground-based nuclear energy in space, creating a habitable lunar base and starting industrial exploration of the Moon, ensuring the protection of the Earth from asteroid-comet hazard.