Nuclear Reactors
The following are examples of nuclear technology that could be used for propulsion in space.
Nuclear Thermal Rocket Engine (NTR)
Click here for diagrams of similar nuclear rockets.
Gas Core Nuclear Fission Rocket Engine (GCNR)
This is a gas core nuclear fission rocket engine (GCNR). Cold hydrogen is pumped into the main axis of the rocket's engine. Then, hydrogen circulates creating a "Re-circulation Vortex" in the chamber. Uranium particulate is injected into the center of the vortex until the uranium accumulates to near-critical mass. After the chamber is stabilized, control drums in reflector walls rotate causing the uranium to go critical. The hot uranium gas can get to be 55,536 degrees Celsius and radiates energy to surrounding hydrogen which exits through a nozzle to provide thrust.
- http://www.nuclearspace.com/a_gen_legacy.htm
The Hybrid Nuclear Light Bulb / Nuclear-Pumped Laser
This type of propulsion would be ideal for deep space flights because it could obtain high specific impulses and reduce propellant usage. The light bulb part of the system would be useful for the parts of the mission requiring high thrust. It would radiantly transfer energy to a propellant. Then, the impulse of the laser mode would be used for most of the mission.
The current ideas for this system rely on fission energy from the uranium plasma core to be either extracted as radiation and absorbed into the propellant, or to be extracted directly as laser energy.
As far as problems with this system, the following questions still remain:
Reactor/system stability over all operating conditions
Failure modes and safety impacts
Operating lifetime/performance envelope
Fuel/buffer gas separation/recirculation system performance
Overall system reliability
Correlation of electrically heated demonstrations to fission heated operation
Validation of spectral tailoring of radiant heat flux
The performance characteristics of the system show that it would offer superior performance to other nuclear systems. For comparison purposes, the available figures for a solid nuclear system are also given. They are shown in red:
| Engine weight (kg) | 31,800 9,100 |
| Engine power (MW) | 4,600 |
| Total propellant flow (kg/sec) | 22.4 |
| Specific impulse (sec) | 1,870 830 |
| Thrust (N) | 410,000 334,000 |
| Engine thrust-to-weight ratio | 1.3 |
| Height (m) | 7.0 10.7 |
- G.H. Miley, University of Illinois, Fusion Studies Laboratory. Space Technology and Applications International Forum.