interstellar dust is charged. You can deflect it with a magnetic field.
Assuming high genetic diversity is wanted, frozen eggs and sperm are a lot more mass efficient than a live colonist.
You'll need an AI that is equivalent to human to bring up the children, but once you have an AI like that one wonders why do you need the meat bodies at all, except may be for sentimental reasons. I do agree these kind of seed ships are the most likely way of interstellar colonization, we're pouring huge amount of money into AI/biotech/nanotech research, and these technologies will likely mature well before any propulsion tech required for generation ships.
All it would take to send a gaiaspore to another star, would be for the 24th centurys Elon Musk or Jeff Bezos to buy a habitat, fit it with ion motors and nuclear reactors to run them and to replace sunlight with artificial light, buy a bunch of uranium, thorium or plutonium, and send a million volunteers on their way.
According to Grun et al. (2005), dust particles have a mass ranging from 10^-9 to 10^-14 g, or 10^-12 to 10^-17 kg, and a charge ranging from 10^-15 C to 10^-17 C. If we want the radius of the dust particle’s path to be say 1000 m while we are flying by at 0.10 c, then the strength of the magnetic field we will need will be:B = mv/qr = (10^-12 kg)(3 x 10^7 m/s)/(10^-15 C)(1000 m) = 3 x 10^7 TTo generate a 3 x 10^7 T field, we would need a loop of wire carrying a current of:I = B2(pi)r/u = (3 x 10^7 T)(2)(3.14)(1000 m)/(10^-7 Tm/A) = 2 x 10^18 A which is basically impossible, even with superconducting wires.So I guess it would take way too much energy to have a magnetic field strong enough to deflect the dust particles.It would be different if we were going much slower.ReferenceEberhard Grün, Ralf Srama, Harald Krüger, Sascha Kempf, Valeri Dikarev, Stefan Helfert, Georg Moragas-Klostermeyer (2005) 2002 Kuiper prize lecture: Dust astronomy. Icarus 174:1-14
nope nope nope! new schemes don't require bombs. they require lasers and a deuterium pellet. no propulsion systems that requires ultra-miniaturized fusion bombs by the thousands will ever be cleared by any government.
People seem fond of Orion style propulsion, but I see no reason not to simply use nuclear-electric. If you are going to take thousands of years for the journey, then you don't need high thrust.
TRL's for technologyFission 8 Well Nerva got to ground test.
Fusion 2-3?Fusion 1? (Well the Sun works)
Ability to detect an Earth sized planet with sufficient detail to know it won't kill them outright. 3?
To accelerate a multi-billion-ton worldship to 1% of light speed in even 100 years requires quite significant thrust (billions of newtons).
Essentially, yes, but I'd think the worldship-habitat would be custom built to survive super-high-speed impacts and the significant acceleration of the nuclear pulse engine, while O'Neill colonies/habitats might be pretty lightly built.
OK, cool, thanks for doing the math. So really really big ships with super thick asteroid material shielding are probably the way to go.