by New drive ideas for movement in space seem to be a dime a dozen lately. Alongside the typical dispute between solar sails and chemical propulsion lies a possible third way – a nuclear rocket engine. While we have discussed them here universe today Previously, NASA’s Institute of Advanced Concepts awarded a grant to a company called Positron Dynamics to develop a novel nuclear fission rocket engine (FFRE). It could strike a balance between the horsepower of chemical engines and the longevity of solar sails.
What is a fission fragment rocket engine?
FFREs are not a new concept per se, but many must overcome massive technical hurdles before they can be considered useful. Their advantages, such as high specific impulse and extremely high power density, are offset by their disadvantages, such as the need for a complicated form of plasma levitation technology.
Positron Dynamics hopes to improve this balance by utilizing two separate breakthroughs originating from other research areas. The first novel approach would be to pack the fissile material into an ultra-lightweight aerogel. The second would be to implement a superconducting magnet to confine these fission particles.
The airgel approach would make a rocket more fuel-efficient, Positron Dynamics believes.
NASA/Ryan Weed
FFREs use essentially the same nuclear process that powers energy-producing nuclear power plants on Earth. However, they not only generate electricity, but also thrust, and very high thrust at that. However, sending an entire ingot of uranium fuel, like that used in fission reactors here on Earth, into space is not practical.
Embedding the fuel in even one of the lightest known human substances solves this problem. Aerogels are exceptionally airy materials that look ethereal when someone is holding them, as seen in the main image above. Embedding fuel particles in them for the fission reaction would be a convenient way to hold the fuel together while still allowing the overall structure to be light enough to be lifted into orbit.
However, the structure of the aerogels themselves would not do much to contain the fission fragments when they break apart. This would require a massive external force, and this is where the superconducting magnet comes in.
UT video on the benefits of the core drive.
Superconducting magnets are typically used in experimental fusion facilities, where they are used to contain the plasma needed to heat fusion fuel, but which would otherwise destroy any normal material. With all the recent interest in fusion research, high-performance magnets have also received additional research attention.
Adding one to a FFRE would allow engineers to direct the fission fragments all in the same direction, effectively turning them into a thrust vector. It has the additional advantage that the fragments cannot destroy other parts of the engine.
So far it’s all very theoretical, because there are still a lot of hurdles to overcome. But that’s what NIAC is for—funding early-stage projects and trying to mitigate risk. Perhaps one day FFREs will be able to reach the sweet spot of speed and fuel efficiency that so many rocket scientists dream of.
This article was originally published on universe today by Andy Tomaswick. Read the original article here.
