Nuclear Engine Rocket

I had previously proposed nuclear rocket engines. After reading about the “Thin Film Isotope Nuclear Engine Rocket (TFINER)”, I wanted to re-emphasize my idea.

TFINER’s basic concept is to manufacture thin sheets of a radioactive isotope and directly use the momentum of its decay products to generate thrust. The baseline design is a ~10-micron thick Thorium-228 radioisotope film which undergoes alpha decay with a half-life of 1.9 years. The subsequent decay chain cascade produces daughter products with four additional alpha emissions that have half-lives between 300ns and 3 days. A thrust is produced when one side of the thin film is coated with a ~50-micron thick absorber that captures forward emissions. Multiple “stages” consisting of longer half-life isotopes (e.g. Ac-227) can be combined to maximize the velocity over extended mission timelines.

My proposition is to use the same Thorium isotope. However instead of letting the decay particles scatter around almost uncontrolled, I propose to collect them in a pressure chamber. Thorium-228 undergoes alpha decay, which is basically a Helium atom with no electrons. Due to its positive charge, it would repel other Helium ions which increases the internal pressure. The decaying of Thorium yields Radium atoms which also undergoes an alpha decay (half-life of 3.6 days) and yields Radon gas. As a result, all decay particles and yields can be exhausted from the nuclear engine as pressurized gas. Decaying also generates heat which accelerates the gas atoms further.

The advantage of my proposition is higher thrust generation and more compact design. A spacecraft that unfolds and covers large area is susceptible to micrometeoroid impacts compared to a smaller one. My proposition also allows throttling of the thrust and simpler thrust vectoring.