Fusion or Antimatter?

Getting around interplanetary space is a challenge for chemical rockets – it’s barely worth doing for probes, and pointless for people. Eventually something better is needed. Two high-tech approaches are to use nuclear fusion or antimatter annihilation. Another old paper (1996) makes a detailed comparison…

Comparison of Fusion/Antiproton Propulsion
Systems for Interplanetary Travel

…and fusion wins easily. Antimatter energising of propellent is incredibly tricky and difficult, producing a lot of pesky neutrinos and nasty gamma-rays. The gammas can be effectively thermalized by big tungsten shields, but with a weight and cooling system penalty.

Much easier to use some kind of fusion ignition system (Stanley Borowski, the author, examines several) and enjoy the higher performance allowed by much easier to handle fusion by-products. The best performance is, of course, pulsed fusion using fuel pellets detonated by lasers (Inertial Confinement Fusion), which is what sent the good ship “Daedalus” to the stars in the JBIS’s 1973-1978 study. For interplanetary flight a more modest performance is sufficient – roughly 1/10th the exhaust velocity gets a ship to Pluto and back on a single tank in less than 2 years.