Nuclear SpaceCraft Propulsion By David Gitz S.E.D.S Representative
Nuclear Pulse Propulsion • How-To’s • Applications • Impacts • Technologies
The Basics • Nuclear Reactions: • Fission • Fusion • The fission of two nuclei of iron generally absorbs energy while the fission of nuclei heaver than iron releases energy. • The fusion of two nuclei of iron generally releases energy while the fusion of nuclei heaver than iron absorbs energy.
Nuclear Fission 1 Neutron Energy 3 Neutrons
Nuclear Fusion • Powers the stars • Through nuclear fusion the stars have produced every atom in the universe that is lighter than iron. • How did we get everything else? Supernovae. But that’s for another time…
Nuclear Fusion • Protons don’t like being too close (electrostatic force). • The fucion of lighter nuclei, creating a heavier nucleus and a free neutron, will generally release more energy than it took to force them together.
Nuclear Pulse Propulsion • Hard to efficiently confine a nuclear reaction, like a normal rocket engine. Way too energetic. (maybe though…intertially confined fusion (ICF)) • Next best thing: Don’t. Blow it up behind you and ride the wave.
Project Orion • http://www.nuclearspace.com/images/gallery/movies/project_orion.wmv
Performance • Exhaust Velocity: 20,000 – 30,000,000 m/s with MegaNewtons of Thrust. • Most spacecraft propulsion systems can deliver with one of these factors, but using nuclear propulsion is the only way to get both. • What does this mean, anyway? • Exhaust Velocity: Effectively limits the velocity of your craft. A high exhaust velocity means you can go fast. • Thrust: Acceleration • Using Nuclear Pulse Propulsion, you can launch from the ground and approach .1 c with the same propulsion system. • Probably wouldn’t though, due to nuclear fallout. • Was designed to be a feasible system in 1958!
Project Deadalus • Study conducted by the British Interplanetary Society. • Interstellar unmanned spacecraft • Fusion Rocket • Designed to get to Barnard’s Star (5.9 LY) in 50 years. • Flyby only.
Project Daedalus Operations • Used pellets of deuterium that would be ignited in a reaction chamber by ICF using electron beams. 250 pellets detonated per second, and the resulting plasma would be directed by a magnetic nozzle. • Requirements: • Telescopes • Probes • Repair-Drones • Master Computer • Master Computer would have to be very intelligent to maintain spacecraft, scientific measurements and navigation.
Project Longshot • Designed by the US Naval Academy • Unmanned probe designed to travel to Alpha Centauri B. • Used a nuclear fission reactor to power numerous lasers to ignite fusion using ICF. • Orbit Alpha Centauri B. • Travel time about 100 years.
Impacts • Safety • Environmental • Economic • Political
Impacts on Crew Safety • Would require a several meter thick steel pusher plate to provide shielding. Radiation shielding effectiveness increases exponentially with shield thickness. • Other factors that haven’t been specifically addressed, like nuclear fallout left in craft’s wake.
Impacts on the Environment • Best idea is to not ignite nuclear’s until the craft is above the magnetosphere so that the fallout (charged ions) won’t be trapped in the Earth’s magnetic field and won’t come down to the planet. • Also, if ignited low enough, could cause severe damage through EMP.
Impacts of Economics • Any Nuclear Pulse spacecraft that would be able to travel to other star-systems would require very large funding, probably way beyond any individual nation. • The large Orion design (travel to Alpha Centauri) would weigh approximately 8 million tons and would be more of an interstellar ark than a spacecraft. • Project Daedalus would be most efficiently assembled in Jupiter Orbit, since it’s fuel would be Helium-3, abundant in that region.
Political Impacts • All nuclear pulse propulsion systems and their test programs violate the Partial Test Ban Treaty of 1963. Treaty prohibits all nuclear detonations except those that take place underground. • Would require a period of world stability unlike anything seen to date, since there is obviously a risk of nuclear warfare and terrorism.
Technologies • Inertially Confined Fusion • Repair-Drones • Probes • Master Computer
Inertially Confined Fusion 1 Pellet injection gun 2 Superconducting field coils (4) 3 Electron beam generators 4 Plasma exhaust jet 5 Magnetic field 6 Energy extraction coils 7 Frozen nuclear pellet 8 Nuclear explosion 9 Reaction chamber Note: 250 explosions per second
Repair-Drones • Computer controlled Robots required to check out and activate probes • Travel around the parent craft • Check system failures and rectify them • Powered by individual nuclear reactor. • Deploy smaller probes to investigate the interstellar environment during the cruise phase of the flight.
References • http://www.spacedaily.com/news/nuclearspace-03h.html • http://www.angelfire.com/stars2/projectorion/ • http://en.wikipedia.org/wiki/Nuclear_pulse_propulsion • http://www.daviddarling.info/encyclopedia/D/Daedalus.html • http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19890007533_1989007533.pdf • http://www.bisbos.com/rocketscience/spacecraft/daedalus/daedalus.html • http://www.nuclearspace.com • “Faster than Light, Superluminal Loopholes in Physics” by Dr. Nick Herbert
Further Reading • “Project Orion: the True Story of the Atomic Spaceship” by George Dyson • “Project Daedalus”, Journal of the British Interplanetary Society, 31, Supplement-1978