High Performance Nuclear Rockets
The energy density of chemical propellants may be easily shown to be inadequate for "Single Stage to Orbit" or interplanetary missions with reasonable mass ratios, and condemns interplanetary missions to unreasonably long transit times. The original goal of the ROVER program was therefore a single-stage nuclear rocket capable of lifting ICBMs. However, the reactor design and geometry the ROVER team locked NERVA into can easily be shown to not be capable of achieving the ROVER program goal.
The ROVER proposed NERVA design was based on an inadequate understanding of the needs of rocketry relative to reactor design, and in particular, on the importance of power per unit mass. A small group within the ROVER program did have a background in rocketry, and proposed an alternate reactor design, DUMBO, that would have been able to achieve the program goals. I will discuss the physics of the DUMBO design, why DUMBO would have succeeded where NERVA failed, and the political factors that led to DUMBO being de-funded. Finally, I will briefly summarize the spectrum of other proposed high-performance nuclear rockets.