DARPA will develop a rocket nuclear engine
DARPA agency in 2020 plans to begin work on a nuclear rocket engine . The task is to develop such an engine that could be used to move space transporters within the lunar orbit. The financing of the project is $ 10 million, and it is called ROAR (Reactor On A Rocket).
The US military (in any case, those related to this project) believe that nuclear reactors will make it possible to establish an effective system for moving spacecraft. At the same time, the operating time reserve of the nuclear engine will be somewhat larger than the standard engines currently in use.
The calculation is based on the fact that the flow rate of the working fluid will go slower. Well, as a working fluid they will use liquid gas, possibly hydrogen. The working fluid inside the engine heats up, there is an ejection through the nozzle, which moves the spacecraft forward. This makes it possible to significantly increase the efficiency of the use of nuclear fuel. In turn, this means that the size of the rocket can be reduced, and the flight hours can be reduced.
The fuel for the nuclear engine will be uranium, where the content of the U-235 isotope will be more than 5%, but less than 20%. Modern submarines with a nuclear reactor use highly enriched uranium fuel, the percentage of which is up to 90%. But weakly enriched uranium is used at nuclear power plants (only 3-5%).
The development of a nuclear engine is scheduled for 2020 because up to this point it is planned to carry out a number of research projects. Some of them are devoted to the creation of technologies that are planned to be used in the reactor. The project can be represented as a Lego constructor, for which some of the elements are missing. Unfortunately, there is a start date, but the planned end of the project is not indicated - so development can take many years.
As for the idea of using a nuclear engine in space, it does not belong to DARPA, but to NASA. The agency, together with several partners, has been developing since the mid-20th century. Research was conducted on the creation of aircraft with a nuclear rocket launcher in the USSR. They did not receive development in either the United States or the USSR for three main reasons. The first is the high risk of an accident, which, provided there is a nuclear reactor on board, can lead to the most sad consequences. The second is purely technical difficulties in creating such a spacecraft. Third - the need to create massive radiation protection for the crew.
True, in the middle of the 20th century, developers tried to solve the problem of creating an apparatus that would rise from the surface of the Earth. Now we are talking about starting already from orbit. The spacecraft will be launched into orbit with conventional chemical-propelled launch vehicles. In principle, it is possible to create an apparatus that would start from the surface of the planet using nuclear fuel, but there are much more difficulties than the case of orbital operations.
In addition, previously, scientists tried to create a nuclear electric propulsion system. In this case, the reactor generates electricity that is supplied to electric rocket engines (they can be plasma or ion). Now it is the nuclear rocket engine that is being developed, the working fluid of which enters the reactor, is heated and thrown out through the nozzle.
Now the work is carried out by other organizations, for example, BWXT Nuclear Energy. This company is the successor to Babcock & Wilcox, who built the world's first nuclear reactors and nuclear submarines. In recent years, the company's specialists have been studying the reliability of nuclear rocket engines.
The advantage of a nuclear engine is also the fact that the design of the reactor reduces the amount of fuel needed to perform pulse maneuvers. The engine can be restarted several times. The astronauts will be in a compartment protected from radiation - of course, if we talk about manned spacecraft.
DARPA is a highly multilateral organization. So, recently it was reported that she was engaged in the development of artificial intelligence of a new generation. The agency believes that the new AI will be many orders of magnitude smarter than its predecessor, and the robot will reason based on “common sense”. Much more was invested in this project than in a nuclear engine - not millions of dollars, but $ 2 billion. The director of the DAPRA military science department, Valerie Browning, said: “The super idea of the AI Next project is this: to turn a car from an instrument, sometimes very worthy, into a real partner, a trustworthy employee. ”