MOSCOW, October 29, Tatyana Pichugina. NASA has selected companies that will create prototypes of nuclear engines for spacecraft. In Europe, they are reporting the development of small modular reactors for interplanetary transport. In Russia, the nuclear tug project is being announced at the highest level. What are the advantages of these programs over traditional rocket engines — in the RIA Novosti material.
At the dawn of the nuclear era
In the middle of the 20th century, the idea of using nuclear energy for space purposes appeared. Scientists have proposed replacing the combustion chamber in a rocket engine with a nuclear reactor, passing liquid hydrogen through its core, heating it to several thousand Kelvin and releasing the resulting gas from the nozzles. This type of engine came to be called nuclear thermal. Another option is to combine reactor thermal energy with an electric rocket motor.
In the 1960s, nuclear propulsion was actively being worked on around the world. In the USSR they achievedspecific thrust up to 9000, in the USA — up to 7500 meters per second. By that time, it became clear that such installations were unstable and unsafe; moreover, new liquid engines appeared, and the prospect of flights into deep space was postponed indefinitely. The Americans designed and tested 23 nuclear reactors for space, but none were launched.
In 1986, the Chernobyl accident almost stopped all work in the USSR. In Russia, projects to create a nuclear engine were resumed after 2010.
The US has set deadlines
In recent years, interest in creating a spacecraft with a powerful power plant has reawakened. Scientists propose a variety of projects using nuclear, thermonuclear and solar energy sources.
Powerful engines promise the delivery of tens of tons of cargo to geostationary orbit and to the Moon, new ways to get rid of space debris, asteroid and comet protection. In addition, they significantly reduce the flight time to Mars and other planets, which makes manned expeditions into deep space quite feasible.
Three years ago, NASA announced its intention to create two types of nuclear engines — thermal and electric. Manufacturers were asked to submit ideas, from which the best ones would be selected for further funding.
For deep space exploration by automatic vehicles, existing engines are sufficient. But in the coming decades, everything will change, NASA believes. In particular, the agency is interested in a manned mission to Mars, which includes the return of astronauts.
Now the flight to Mars and back will take about four years. During this time, people will receive lethal doses of radiation. Nuclear power can be completed in two years, which will significantly reduce the risks to the health of the crew and the level of stress from a long dangerous journey. You can carry significantly less cargo on board; in addition, the nuclear engine is more compact and does not require refueling.
The direction is supervised by NASA's Marshall Space Center in Alabama in collaboration with scientific organizations. Scientists are testing new types of fuel for reactors. There are many unresolved issues, for example, high temperature — about five thousand kelvins. To work in such conditions, you need to create special materials.
In January, information leaked to the media that NASA plans to test a nuclear-powered engine as early as 2027. The Office of Advanced Research Projects of the US Department of Defense — DARPA, which has already attracted General Atomics, Lockheed Martin and John Bezos' Blue Origin, got involved. For the year, $110 million was allocated for these purposes.
At the end of July, DARPA chose aircraft manufacturer Lockheed Martin. She was tasked with developing the design, prototyping the engine and rocket, and conducting testing. The reactor will be built by BWX Technologies. The project is funded by the $500 million DRACO (Demonstration Rocket for Rapid Assault beyond Lunar Orbit) program.
Unlike the first projects of the middle of the last century, the current ones will use enriched uranium instead of weapons-grade uranium. The reactor must be turned on only after spacewalk to minimize the consequences for Earth in the event of an accident. The test flight will take place in an orbit at an altitude of 700-2000 kilometers. This ensures that the rocket and reactor remain there for at least 300 years until dangerous radioactive elements decay.
In October, it was announced that the US Air Force Research Laboratory had opened another program — JETSON — to fund projects to develop orbital nuclear rockets. Contracts have been signed with nuclear energy companies Intuitive Machines (their lander is expected to launch to the Moon this December), Lockheed Martin and Westinghouse Government Services to build small nuclear rocket engines for satellites until 2025.
Nuclear tug named «Zeus»
Experience in operating reactor nuclear power plants in space Only our country has it. In the 1960-1980s they were tested on spacecraft of the Cosmos series and experimental scientific and technological devices Plasma-A.
In Russia, work has been going on for more than ten years to create a transport-energy module (TEM) based on a megawatt-class nuclear power plant. It will become the basis of a space tug. In 2020, on the initiative of the head of Roscosmos at that time, Dmitry Rogozin, it was named “Zeus” (the entire program is called “Nuklon”). And soon they presented the scheme.
The TEM is based on a long frame, thanks to which nuclear fuel will be separated as much as possible from the main compartment with equipment and people. The engine is a compact nuclear reactor, a system for converting thermal energy into electrical energy, a system for collecting excess heat, propulsion ion engines with a power of up to several tens of kilowatts and with a specific impulse of over seven thousand seconds.
The TEM, ready for a space mission, will be assembled and tested on Earth, then in a folded state it will be launched in parts into an orbit at an altitude of more than 800 kilometers, where it will be tested, the reactor will be launched and docked with the payload module. Next comes acceleration along a spiral trajectory to spacewalk, undocking and return to low-Earth orbit. The lifespan of such an engine is ten years. During this time it will make several flights.
It was previously reported that the preliminary design of the space tug should be ready by mid-2024.
According to Vladimir Koshlakov, general director of the Keldysh Center, tests of the droplet emitter-cooler for the Zeus reactor will take place on the ISS in 2024. Earlier, former first deputy head of Roscosmos Yuri Urlichich announced the development of a prototype nuclear power plant in 2025. Assembly of the space tug is planned to begin in 2030.
During a visit to RSC Energia on October 26, Vladimir Putin announced his support for the creation of a nuclear tug.
“Right now I simply don’t know the details related to the planned financing, but we will definitely not abandon this topic at all and will provide the necessary amount of money for this so that the program is done,” said the head of state, adding that deep space exploration is impossible without this.
Faster than the speed of light
Powerful solar-powered electric rocket tug (SEP ) are currently being created at NASA. It is lighter than other types of transport, making it easier to launch into orbit. Such a machine is promising for work in near-Earth space. Its key element is a solar battery with an area of 800 square meters and an electrical power of 300 kilowatts. The energy generated in them will directly power the xenon engine.
Another promising idea is a thermonuclear engine. For example, scientists from the University of Washington reported on their work on it. With such an installation, a flight to Mars will take a month — three at most. Researchers have already tested various design elements in the laboratory and came to the conclusion that, in principle, it is possible to create such an energy source for space. It will require very little fuel; the main problem is to start a thermonuclear reaction and hold the plasma with strong magnetic fields. Essentially, you need to light up a small Sun inside the rocket. So far this has only been possible for a few microseconds.
In July, scientists from the British company Pulsar Fusion reported the construction of the largest thermonuclear engine measuring eight meters. It will create jet thrust directly, bypassing the conversion of thermal energy into electrical energy. Such a system is much more efficient and can accelerate the ship to a speed of over 800 thousand kilometers per hour. The thermonuclear reaction in the installation is planned to be ignited in 2027.
But scientific thought goes further. Why not accelerate the spaceship to the speed of light and beyond? To do this, science fiction writers came up with a warp drive that uses space-time structures called warps (bubbles). They move through space at a constant speed, maintaining their shape. The warp requires a huge amount of energy to move. Most often, various exotic forms of matter, such as negative energy, are proposed as a source. However, scientists from the University of Göttingen have calculated that they can get by with ordinary ones. Theorists claim that with a warp engine it is possible to fly to the closest star system to us, Proxima Centauri, in a matter of years. Moreover, warps do not slow down time for people in a spaceship inside a “bubble”. Time flows there the same way as outside. So, when they return to Earth, the travelers will be the same age as their peers. It remains to figure out where to get the energy for such an engine.