A comment on one part of it:
Non-fission triggers are a laudable goal of fusion propulsion research, but they pose a conundrum for slowing proliferation of thermonuclear weapons.
Nuclear weapon proliferation is generally irrelevant for countries with the capability to move freely around the solar system and having a far superior energy source.
Kinetic Energy is More Robust and Scales Higher than Nuclear Bombs
Any technology (like a good fusion rocket) that can get anything to 29% of light speed has military implications. Even moderately advanced VASIMR scale technology and robotic electric solar sails would let you fairly free roam out to near earth asteroids and the asteroid belt. Big rocks could be diverted to crush fixed targets on earth.
Moving up the kinetic energy scale quickly outclasses any existing nuclear bombs in destructive force and kinetic energy weapons are harder to defend against than nuclear bomb. A nuclear bomb has fragile mechanisms. A kinetic energy rock still has all of its destructive energy if it is broken into pieces.
Think about the dinosaur killing asteroid versus a nuclear bomb.
Dinosaur asteroids are discussed here
Near-Earth Objects are from the Anglo-Australian Observatory's research astronomer Duncan Steel's book Rouge Asteroids and Doomsday Comets. About 2,000 objects massive enough (1 km diameter) to cause global catastrophe are known to cross Earth's orbit. Such an impacting object would wipe out 25% of humanity.
If a 10km diameter object impacted at the point at which it struck it would have a velocity of roughly 100,000 km/h. At this velocity there would have been an initial blast (with an estimated force of many millions of tons of TNT) which would have destroyed everything within a radius of between 400 and 500km, including the object. At the same time large fires would have been started by the intense shock wave which would have traveled long distances. Trillions of tons of debris (dust, gases and water vapour) would have been thrown into the atmosphere when the object vaporized. Many enormous tidal waves would be started causing even more damage, the evidence of such waves has been found all the way round the Gulf of Mexico. Along with the tidal waves the blast would also start a chain reaction of earthquakes and volcanic activity there would have also been very high winds caused by the blast. In the days and weeks following the impact the cloud of debris would have been carried over large distances by the post blast high winds. This will have caused months of darkness and a decrease in global temperatures. After this there would have been an increase in temperatures caused by the large amounts of CO2 released by what would have been global fires. Eventually this would cause chemical reactions that would result in the formation of acid rains.
Advanced space tech means super-kinetic weaponry. It does not matter how you do it but if you have freedom of cheap movement to orbit and around the inner solar system – you can kick the ass of anybody stuck on earth.
Abundant, Cheap Energy Makes Your Country Rich and Powerful
Mastering fusion for energy generation and your country has 10 to thousands of times the energy budget of non-fusion enabled countries. A country with virtually no upper bound on cheap, clean energy is insanely rich.
Super energy rich means you are super wealthy. Energy rich and money rich translates to military strength. See World War 2 where the USA outproduced Japan and Germany by making more tanks and other weapons. German tanks were better but the US could make four or more tanks for every German Tank. So the German Tank shoots and destroys one Sherman tank and the others flank and destroy the German tank. The first wrecked Sherman tank is repaired and a new tank crew is put into it.
Comments and Discussion
A comment at Centauri Dreams by Eniac
While your point is well taken, I think it is hard for kinetic weapons to outclass nuclear. The best you can reasonably do, I think, is park your weapons in Earth solar counter-orbit, where they would have a relative velocity of around 60 km/s, and could be delivered fairly quickly if there are enough of them. IIRC, even at that speed, you are still way below the energy density of fusion fuel. In fact, this would have to be true, otherwise there would be no hope to reach relativistic velocities using fusion.
Also, kinetic weapons are not as fail-safe as nuclear ones can be made. A tiny mistake and you could hit the wrong side of the planet…
This and a comment in this thread about the high speed of 29% of light speed. The 29% of light speed level is not needed for optimal utility of kinetic weapons. 29% of light speed is particle accelerator speeds for macro scale objects. E= M*C^2 so the energy of such a high speed objects would be more than a mass that gets converted to fusion.
Adam Crowl comment from Centauri Dreams thread:
Of course once belligerents are armed with fusion weapons a vehicle propelled to high enough speeds to match fusion bombs in its kinetic energy is a rather less steerable device than the equivalent explosive device fired off at reasonable speeds. If we could launch relativistic missiles then the game changes, but a perimeter of high-acceleration interceptors might make such missiles ineffective – they have even less time to deploy counter-measures than we do to deploy (already emplaced) defenses against them. If can develop Jordin Kare style micro-sails launched at mega-gee accelerations then we have the making of relativistic guns – for defence or offence.
This is all a bit off-topic, but then the binary nature of interstellar technologies is nowhere more stark than when we consider fusion propulsion, especially via “bombs”. I hope we’ll get all our eggs out of this one basket some time soon and Winterberg’s concepts might well help us do it too.
As Obi-Wan says in Star Wars 6: It's over Anakin, I have the high ground.
Lobbing asteroids (rocks) of varying sizes and speeds or rod like projectiles from space would have a considerable advantage over someone with just ground and orbital defences. Targeting a deflection of a massive object pays back many orders of magnitude in leveraged energy invested. Various uses of gravity of planets and sun to accelerate objects. Shepard objects into holding patterns. Hide objects by coverings which blend into the background of space or use metamaterials for invisibility.