NASA Plan to send a manned mission to Mars Over the next 10 years – but A journey of 140 million miles (225 million kilometers) to the red planet A round trip can take months to years..
This relatively long flight time is a result of the use of conventional chemical rocket fuel. The agency is currently developing an alternative technology to chemically propelled rockets called nuclear thermal propulsion that uses nuclear fission. One day power A rocket You can travel in just half the time.
Nuclear fission involves harvesting the incredible energy released when atoms are split by neutrons. this This reaction is known as nuclear fission reaction. Nuclear fission technology is well established in power generation and nuclear submarines, and its application to propelling or powering rockets could one day provide NASA with a faster, more powerful alternative to chemically powered rockets.
NASA and the Defense Advanced Research Projects Agency Jointly developed NTP technology. They plan to deploy a prototype system in space in 2027 to demonstrate its capabilities, which could be the first system of its kind built and operated by the United States.
Nuclear thermal propulsion will also be able to provide electricity someday maneuverable space platformIt would protect American satellites in and out of Earth’s orbit. However, this technology is still under development.
I Associate Professor of Nuclear Engineering, Georgia Institute of Technology whose research group Build models and simulations to improve and optimize the design of nuclear thermal propulsion systems. My hope and passion is to help design a nuclear thermal propulsion engine to carry a manned mission to Mars.
Nuclear propulsion and chemical propulsion
Traditional chemical propulsion systems use chemical reactions involving a light propellant, such as hydrogen, and an oxidizing agent. Once mixed, these two ignite, resulting in the propellant coming out of the nozzle very quickly and propelling the rocket.
Scientists and engineers are working to develop a nuclear thermal propulsion system that pumps hydrogen propellant into a nuclear reactor to generate energy and then injects the propellant through a nozzle to lift a rocket. NASA Glenn Research Center
These systems do not require an ignition system and are therefore more reliable. But these rockets can be heavy because they need to carry oxygen into space. Unlike chemical propulsion systems, nuclear thermal propulsion systems rely on nuclear fission reactions to heat the propellant, which is then ejected from a nozzle to produce propulsion or thrust.
In many fission reactions, researchers send neutrons toward the nucleus. light isotopes of uraniumuranium-235. Uranium absorbs neutrons and produces uranium-236. The uranium-236 then splits into two fragments (fission products), and the reaction releases various particles.
Nuclear fission reactions produce large amounts of thermal energy.
Over 400 nuclear reactors In operation around the world Currently, nuclear fission technology is used. Most of these reactors in operation are light water reactor. These fission reactors use water to slow down neutrons and absorb and transfer heat. The water directly generates steam in the reactor core or steam generator, which drives turbines and generates electricity.
Nuclear thermal propulsion system It works in a similar way, but uses a different nuclear fuel that is high in uranium-235. It also operates at very high temperatures, making it extremely powerful and compact. Nuclear thermal propulsion systems have approximately 10 times more power density than conventional light water reactors.
Nuclear propulsion may have an advantage over chemical propulsion some reasons.
In nuclear propulsion, the propellant is released from the engine nozzle very quickly; high thrust. This higher thrust allows the rocket to accelerate faster.
These systems also have high specific impulse. specific impulse Measures how efficiently propellant is used to generate thrust. Nuclear thermal propulsion systems have about twice the specific impulse of chemical rockets, so they have the potential to cut travel times in half.
History of nuclear thermal propulsion
The U.S. government has been funding the development of nuclear thermal propulsion technology for decades. From 1955 to 1973 NASA, general electricand Argonne National LaboratoryTwenty nuclear thermal propulsion engines were manufactured and ground tested.
However, these pre-1973 designs relied on highly enriched uranium fuel. This fuel is no longer used for the following reasons: Danger of spreador risks associated with the proliferation of nuclear materials or technology.
of Global Threat Reduction Initiativelaunched by the Department of Energy, National Nuclear Security Administrationaims to convert many of the research reactors that use highly enriched uranium fuel to High Analytical Low Enriched Uranium (HALEU) fuel.
High-concentration, low-enriched uranium fuel contains less material that can undergo fission reactions compared to highly enriched uranium fuel. Therefore, the rocket needs to carry more HALEU fuel, making the engine heavier. To solve this problem, researchers are investigating special materials that allow these reactors to use fuel more efficiently.
NASA and DARPA Demonstration rocket for agile cislunar operationsor the DRACO program, aims to use this highly analytical, low-enriched uranium fuel in nuclear thermal propulsion engines. The program is scheduled to launch a rocket in 2027.
As part of the DRACO program, aerospace company Lockheed Martin partnered with BWX Technologies to Develop reactor and fuel designs.
The nuclear thermal propulsion engines being developed by these groups must comply with specific performance and safety standards. It requires a core that can operate for the duration of the mission and perform the operations required for high-speed travel to Mars.
Ideally, the engine should be able to produce high specific impulse while meeting the requirements of high thrust and low engine mass.
ongoing research
Before engineers can design an engine that meets all these criteria, they need to start with models and simulations. These models help researchers like my group understand how engines handle starting and stopping. These are operations that require rapid and large changes in temperature and pressure.
Because the nuclear thermal propulsion engine is different from all existing nuclear fission power systems, engineers will need to build software tools to work with this new engine.
my group Design and analysis Thermal propulsion reactor using model. We model these complex reactor systems to see how things like temperature changes affect reactor and rocket safety. However, simulating these effects requires large amounts of expensive computing power.
we have been working on Develop new calculation tools Model how these reactors behave during operation. Start and operate without using as much computing power.
My colleagues and I hope that this research will one day help us develop models that can autonomously control rockets.
Dan Kotlyar is an associate professor of nuclear radiological engineering at Georgia Tech. This article is republished from conversation under Creative Commons License. please read original article.
