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Friedwardt Winterberg’s ideas were largely the basis of Project Daedalus, the British Interplanetary Society’s starship design that would evolve into a two-stage mission with an engine burn — for each stage — of two years, driving an instrumented payload to Barnard’s Star at twelve percent of the speed of light.
Some highlights of the interview:
When I first had thought of the fusion-micro-explosion propulsion system almost 40 years ago, I never thought about interstellar spaceflight. I rather thought about a high specific impulse – high thrust propulsion system for manned spaceflight within the solar system. Instead of an interstellar probe, one could build in space very large interference “telescopes” with separation distances between the mirrors of 100,000 km, for example, in the hope to get surface details of other earthlike planets. And by going to 500 AU at the location of Einstein gravitational lens –focus, one could use the sun as a telescopic lens with an enormous magnification.
All this needs a very powerful propulsion system. Before going to Alpha Centauri (or Epsilon Eridani), one should aim at comets in the Oort cloud. Since there is water abundantly available, [this] invites the use of deuterium as rocket fuel. Unlike a DT micro-explosion where 80% of the energy goes into neutrons, unsuitable for propulsion, it is not much more than 25% for deuterium. A deuterium mini-detonation though requires at least 100 MJ for ignition, but this can be provided with a magnetically insulated Gigavolt capacitor, driving a 100 MJ proton beam for the ignition of a cylindrical deuterium target…In reaching the Oort cloud, and there establishing human colonies, one may by “hopping” from comet to comet ultimately reach a “new” earth.
The DD reaction produces T and He3, which in a secondary reaction burn with D. This was “nicely” demonstrated by the 15 Megaton fission triggered deuterium bomb test in 1952.
For propulsion, the pure fusion fire ball can with much higher efficiency (if compared to a pusher plate) be deflected by a magnetic mirror, also avoiding the ablation of a pusher plate. The ignition, requiring more than 100 MJ, can be done with some kind of particle accelerator. The LHC at CERN can store several 100 MJ energy in a particle beam moving with almost the velocity of light. No laser can that do yet. Unlike lasers, particle accelerators are very efficient. And to get a high fusion yield of say about 1kt, cylindrical targets with axial detonation should be used, where a mega-gauss magnetic field entraps the charged fusion products, as it is required for detonation
I would agree that the best way to go interstellar is to rapidly turn human civilization into a kardashev 2 civilization over the next 50-200 years and then expand out through the Oort comet cloud and over to other solar systems.