Nuclear rockets might journey to Mars in half the time

by Dan Kotlyar | Affiliate Prof Nuclear and Radiological Engineering, Georgia Tech

Atlanta GA (SPX) Oct 04, 2024

NASA plans to ship crewed missions to Mars over the subsequent decade – however the 140 million-mile (225 million-kilometer) journey to the pink planet might take a number of months to years spherical journey.

This comparatively lengthy transit time is a results of the usage of conventional chemical rocket gas. An alternate know-how to the chemically propelled rockets the company develops now is known as nuclear thermal propulsion, which makes use of nuclear fission and will at some point energy a rocket that makes the journey in simply half the time.

Nuclear fission includes harvesting the unimaginable quantity of vitality launched when an atom is cut up by a neutron. This response is called a fission response. Fission know-how is effectively established in energy technology and nuclear-powered submarines, and its software to drive or energy a rocket might at some point give NASA a quicker, extra highly effective different to chemically pushed rockets.

NASA and the Protection Superior Analysis Initiatives Company are collectively growing NTP know-how. They plan to deploy and display the capabilities of a prototype system in area in 2027 – probably making it one of many first of its type to be constructed and operated by the U.S.

Nuclear thermal propulsion might additionally at some point energy maneuverable area platforms that might defend American satellites in and past Earth’s orbit. However the know-how remains to be in improvement.

I’m an affiliate professor of nuclear engineering on the Georgia Institute of Expertise whose analysis group builds fashions and simulations to enhance and optimize designs for nuclear thermal propulsion methods. My hope and keenness is to help in designing the nuclear thermal propulsion engine that can take a crewed mission to Mars.

Nuclear versus chemical propulsion

Standard chemical propulsion methods use a chemical response involving a light-weight propellant, corresponding to hydrogen, and an oxidizer. When combined collectively, these two ignite, which ends up in propellant exiting the nozzle in a short time to propel the rocket.

These methods don’t require any type of ignition system, so that they’re dependable. However these rockets should carry oxygen with them into area, which may weigh them down. In contrast to chemical propulsion methods, nuclear thermal propulsion methods depend on nuclear fission reactions to warmth the propellant that’s then expelled from the nozzle to create the driving pressure or thrust.

In lots of fission reactions, researchers ship a neutron towards a lighter isotope of uranium, uranium-235. The uranium absorbs the neutron, creating uranium-236. The uranium-236 then splits into two fragments – the fission merchandise – and the response emits some assorted particles.

Greater than 400 nuclear energy reactors in operation around the globe at the moment use nuclear fission know-how. Nearly all of these nuclear energy reactors in operation are gentle water reactors. These fission reactors use water to decelerate the neutrons and to soak up and switch warmth. The water can create steam straight within the core or in a steam generator, which drives a turbine to supply electrical energy.

Nuclear thermal propulsion methods function in an analogous means, however they use a unique nuclear gas that has extra uranium-235. Additionally they function at a a lot increased temperature, which makes them extraordinarily highly effective and compact. Nuclear thermal propulsion methods have about 10 occasions extra energy density than a conventional gentle water reactor.

Nuclear propulsion might have a leg up on chemical propulsion for a couple of causes.

Nuclear propulsion would expel propellant from the engine’s nozzle in a short time, producing excessive thrust. This excessive thrust permits the rocket to speed up quicker.

These methods even have a excessive particular impulse. Particular impulse measures how effectively the propellant is used to generate thrust. Nuclear thermal propulsion methods have roughly twice the precise impulse of chemical rockets, which implies they might lower the journey time by an element of two.

Nuclear thermal propulsion historical past

For many years, the U.S. authorities has funded the event of nuclear thermal propulsion know-how. Between 1955 and 1973, applications at NASA, Common Electrical and Argonne Nationwide Laboratories produced and ground-tested 20 nuclear thermal propulsion engines.

However these pre-1973 designs relied on extremely enriched uranium gas. This gas is now not used due to its proliferation risks, or risks that need to do with the unfold of nuclear materials and know-how.

The World Menace Discount Initiative, launched by the Division of Vitality and Nationwide Nuclear Safety Administration, goals to transform most of the analysis reactors using extremely enriched uranium gas to high-assay, low-enriched uranium, or HALEU, gas.

Excessive-assay, low- enriched uranium gas has much less materials able to present process a fission response, in contrast with extremely enriched uranium gas. So, the rockets must have extra HALEU gas loaded on, which makes the engine heavier. To resolve this challenge, researchers are wanting into particular supplies that might use gas extra effectively in these reactors.

NASA and the DARPA’s Demonstration Rocket for Agile Cislunar Operations, or DRACO, program intends to make use of this high-assay, low-enriched uranium gas in its nuclear thermal propulsion engine. This system plans to launch its rocket in 2027.

As a part of the DRACO program, the aerospace firm Lockheed Martin has partnered with BWX Applied sciences to develop the reactor and gas designs.

The nuclear thermal propulsion engines in improvement by these teams might want to adjust to particular efficiency and security requirements. They will must have a core that may function at some stage in the mission and carry out the mandatory maneuvers for a quick journey to Mars.

Ideally, the engine ought to have the ability to produce excessive particular impulse, whereas additionally satisfying the excessive thrust and low engine mass necessities.

Ongoing analysis

Earlier than engineers can design an engine that satisfies all these requirements, they should begin with fashions and simulations. These fashions assist researchers, corresponding to these in my group, perceive how the engine would deal with beginning up and shutting down. These are operations that require fast, huge temperature and strain modifications.

The nuclear thermal propulsion engine will differ from all current fission energy methods, so engineers might want to construct software program instruments that work with this new engine.

My group designs and analyzes nuclear thermal propulsion reactors utilizing fashions. We mannequin these complicated reactor methods to see how issues corresponding to temperature modifications could have an effect on the reactor and the rocket’s security. However simulating these results can take loads of costly computing energy.

We have been working to develop new computational instruments that mannequin how these reactors act whereas they’re beginning up and operated with out utilizing as a lot computing energy.

My colleagues and I hope this analysis can at some point assist develop fashions that might autonomously management the rocket.

Associated Hyperlinks

Nuclear and Radiological Engineering, Georgia Institute of Expertise

Rocket Science Information at Area-Journey.Com