The Fission Fragment Nuclear Rocket


Rob Sheldon & Rod Clark
NSSTC / Grassmere Dynamics, LLC

Friday, 13 May 2005
Socialization : 10:15 a.m.
Presentation : 10:30 a.m.

NASA's Human Exploration Initiative (HEI) has refocused attention on high-efficiency, high-thrust rocket propulsion as a necessary technology for transporting human beings through the vast reaches of space as safely as possible. Because of the unpredictability of inclement space weather (solar flares, magnetars etc), this safety concern translates into a requirement for haste in traveling outside planetary protection. Therefore the need for speed has returned attention to the potential of nuclear rockets to provide a unique, high-efficiency, high-thrust propulsion technology. Now there have been many nuclear rocket designs suggested over the past 50 years, some that were developed here at MSFC, but one that has not received much attention is the extreme high-efficiency "fission fragment" rocket, first proposed to our knowledge by George Chapline.

Possessing a specific impulse (ISP) engine > 100,000 seconds makes fission fragment propulsion second only to pure light (or anti-matter) for raw efficiency. Previous designs suffered (as do most nuclear rocket designs today) from concerns about keeping the nuclear core cool. Surprisingly, a recently studied material called "dusty plasma" (such as Saturn's rings) held the secret to a clever solution to the heating problem, since it provides a density intermediate between gasses and liquids. That is, basic research into space physics has provided new materials that can solve old technological problems resulting in improved space capabilities. Think of it as a debt repaid. We will discuss the principles of operation, a schematic design with a weight/size breakdown of the components, and potential HEI mission profiles for this breakthrough technology, with particular attention to radiation hazards.

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