AAWSAP DIRD, Aneutronic Fusion Propulsion II, November 2010

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Figure 14. Comparison of Fusion, Nuclear-Thermal, and Chemical Propulsion
for Same Payload.
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Figure 15. Thrust-to-Weight Ratio and Exhaust Velocity Regimes for Various
Long-Range Space Propulsion Options.
INTERSTELLAR
The ability of fusion propulsion to carry payloads or travelers to a habitable star tens of
light-years away will be limited by the amount of fusion fuel it can transport or gather
along its route. A simple calculation of the amount of energy to move a space-shuttle­
sized veh icle (100 Mg) to the nearest star, Alpha Centauri, indicates a minimum
amount of energy in the mass equivalent of 106 kg. However, in 1960 Robert Bussard
proposed the use of magnetic fields to scoop interstellar hydrogen to fuel a fusion
rocket to propel a spacecra~ now know as the Bussard Ram Jet (shown in Figure 16).20
Although interstellar hydrogen does not fuse, Bussard proposed the use of the stellar
carbon-nitrogen-oxygen (CNO) cycle in which carbon is used as a catalyst to burn
hydrogen through the strong nuclear reaction. However, the size of the scoops and the
fusion power required to maintain them makes this concept unlikely to be realized.
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19