Nuclear rockets could travel to Mars in half the time − but designing the reactors that would power them isn’t easy

[Pelican Press 0]

This is the hidden content, please

• Sign In
• or
• Sign Up

Nuclear rockets could travel to Mars in half the time − but designing the reactors that would power them isn’t easy

NASA

This is the hidden content, please

• Sign In
• or
• Sign Up

over the next decade – but the

This is the hidden content, please

• Sign In
• or
• Sign Up

to the red planet

This is the hidden content, please

• Sign In
• or
• Sign Up

.

This relatively long transit time is a result of the use of traditional chemical rocket fuel. An alternative technology to the chemically propelled rockets the agency develops now is called nuclear thermal propulsion, which uses nuclear fission and could

This is the hidden content, please

• Sign In
• or
• Sign Up

that makes the trip in just half the time.

Nuclear fission involves harvesting the incredible amount of energy released when an atom is split by a neutron. This

This is the hidden content, please

• Sign In
• or
• Sign Up

. Fission technology is well established in power generation and nuclear-powered submarines, and its application to drive or power a rocket could one day give NASA a faster, more powerful alternative to chemically driven rockets.

NASA and the Defense Advanced Research Projects Agency are

This is the hidden content, please

• Sign In
• or
• Sign Up

. They plan to deploy and demonstrate the capabilities of a prototype system in space in 2027 – potentially making it one of the first of its kind to be built and operated by the U.S.

Nuclear thermal propulsion could also one day power

This is the hidden content, please

• Sign In
• or
• Sign Up

that would protect ********* satellites in and beyond Earth’s orbit. But the technology is still in development.

I am an

This is the hidden content, please

• Sign In
• or
• Sign Up

whose

This is the hidden content, please

• Sign In
• or
• Sign Up

builds models and simulations to improve and optimize designs for nuclear thermal propulsion systems. My hope and passion is to assist in designing the nuclear thermal propulsion engine that will take a crewed mission to Mars.

Nuclear versus chemical propulsion

Conventional chemical propulsion systems use a chemical reaction involving a light propellant, such as hydrogen, and an oxidizer. When mixed together, these two ignite, which results in propellant exiting the nozzle very quickly to propel the rocket.

data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///ywAAAAAAQABAAACAUwAOw==Scientists and engineers are working on nuclear thermal propulsion systems that would take hydrogen propellant, pump it into a nuclear reactor to generate energy and expel propellant out the nozzle to lift the rocket.

This is the hidden content, please

• Sign In
• or
• Sign Up

These systems do not require any sort of ignition system, so they’re reliable. But these rockets must carry oxygen with them into space, which can weigh them down. Unlike chemical propulsion systems, nuclear thermal propulsion systems rely on nuclear fission reactions to heat the propellant that is then expelled from the nozzle to create the driving force or thrust.

In many fission reactions, researchers send a neutron toward a

This is the hidden content, please

• Sign In
• or
• Sign Up

, uranium-235. The uranium absorbs the neutron, creating uranium-236. The uranium-236 then splits into two fragments – the fission products – and the reaction emits some assorted particles.

More than 400 nuclear power reactors

This is the hidden content, please

• Sign In
• or
• Sign Up

currently use nuclear fission technology. The majority of these nuclear power reactors in operation are

This is the hidden content, please

• Sign In
• or
• Sign Up

. These fission reactors use water to slow down the neutrons and to absorb and transfer heat. The water can create steam directly in the core or in a steam generator, which drives a turbine to produce electricity.

This is the hidden content, please

• Sign In
• or
• Sign Up

operate in a similar way, but they use a different nuclear fuel that has more uranium-235. They also operate at a much higher temperature, which makes them extremely powerful and compact. Nuclear thermal propulsion systems have about 10 times more power density than a traditional light water reactor.

Nuclear propulsion could have a leg up on chemical propulsion for

This is the hidden content, please

• Sign In
• or
• Sign Up

.

Nuclear propulsion would expel propellant from the engine’s nozzle very quickly, generating

This is the hidden content, please

• Sign In
• or
• Sign Up

. This high thrust allows the rocket to accelerate faster.

These systems also have a high specific impulse.

This is the hidden content, please

• Sign In
• or
• Sign Up

measures how efficiently the propellant is used to generate thrust. Nuclear thermal propulsion systems have roughly twice the specific impulse of chemical rockets, which means they could cut the travel time by a factor of 2.

Nuclear thermal propulsion history

For decades, the U.S. government has funded the development of nuclear thermal propulsion technology. Between 1955 and 1973, programs at

This is the hidden content, please

• Sign In
• or
• Sign Up

,

This is the hidden content, please

• Sign In
• or
• Sign Up

and

This is the hidden content, please

• Sign In
• or
• Sign Up

produced and ground-tested 20 nuclear thermal propulsion engines.

But these pre-1973 designs relied on highly enriched uranium fuel. This fuel is no longer used because of its

This is the hidden content, please

• Sign In
• or
• Sign Up

, or dangers that have to do with the spread of nuclear material and technology.

The

This is the hidden content, please

• Sign In
• or
• Sign Up

, launched by the Department of Energy and

This is the hidden content, please

• Sign In
• or
• Sign Up

, aims to convert many of the research reactors employing highly enriched uranium fuel to high-assay, low-enriched uranium, or HALEU, fuel.

High-assay, low- enriched uranium fuel has less material capable of undergoing a fission reaction, compared with highly enriched uranium fuel. So, the rockets needs to have more HALEU fuel loaded on, which makes the engine heavier. To solve this issue, researchers are looking into special materials that would use fuel more efficiently in these reactors.

NASA and the DARPA’s

This is the hidden content, please

• Sign In
• or
• Sign Up

, or DRACO, program intends to use this high-assay, low-enriched uranium fuel in its nuclear thermal propulsion engine. The program plans to launch its rocket in 2027.

As part of the DRACO program, the aerospace company Lockheed Martin has partnered with BWX Technologies to

This is the hidden content, please

• Sign In
• or
• Sign Up

.

The nuclear thermal propulsion engines in development by these groups will need to comply with specific performance and safety standards. They’ll need to have a core that can operate for the duration of the mission and perform the necessary maneuvers for a fast trip to Mars.

Ideally, the engine should be able to produce high specific impulse, while also satisfying the high thrust and low engine mass requirements.

Ongoing research

Before engineers can design an engine that satisfies all these standards, they need to start with models and simulations. These models help researchers, such as those in my group, understand how the engine would handle starting up and shutting down. These are operations that require quick, massive temperature and pressure changes.

The nuclear thermal propulsion engine will differ from all existing fission power systems, so engineers will need to build software tools that work with this new engine.

My group

This is the hidden content, please

• Sign In
• or
• Sign Up

nuclear thermal propulsion reactors using models. We model these complex reactor systems to see how things such as temperature changes may affect the reactor and the rocket’s safety. But simulating these effects can take a lot of expensive computing power.

We’ve been working to

This is the hidden content, please

• Sign In
• or
• Sign Up

that model how these reactors act while they’re

This is the hidden content, please

• Sign In
• or
• Sign Up

without using as much computing power.

My colleagues and I hope this research can one day help develop models that could autonomously control the rocket.

This article is republished from

This is the hidden content, please

• Sign In
• or
• Sign Up

, a nonprofit, independent news organization bringing you facts and trustworthy analysis to help you make sense of our complex world. It was written by:

This is the hidden content, please

• Sign In
• or
• Sign Up

,

This is the hidden content, please

• Sign In
• or
• Sign Up

Read more:

Dan Kotlyar receives funding from Idaho National Laboratory and BWXT Inc. for research related to nuclear thermal propulsion.

This is the hidden content, please

• Sign In
• or
• Sign Up

#Nuclear #rockets #travel #Mars #time #designing #reactors #power #isnt #easy

This is the hidden content, please

• Sign In
• or
• Sign Up

This is the hidden content, please

• Sign In
• or
• Sign Up