You’d realize that it strictly dominates all other space colonization schemes that have been proposed because it doesn’t waste volatiles for transportation. Certainly O’Neill’s ideas look infeasible in comparison (where do you get the nitrogen to fill those big airspaces? My plan for a baby Bernal sphere intended to be a luxury hotel in LEO still takes 15 starship loads of LN2 for the atmosphere)
Even Musk’s plan to colonize Mars is something that only makes sense to people who were born on a planet. If “grabby” aliens capable of interstellar travel and building such things here they might find the Earth a curiosity at best.
Solar sails are at this time quite useless for most purposes, and always will be if we can't build, fold, and deploy working sails of micrometer thickness, and/or build gigawatt-scale laser launch projectors.
Using ion thrusters it is already the case that we have access to power-generation-limited domain of specific impulse; Nobody thinks a mission at 30,000isp instead of 3,000isp is superior for interplanetary because of the sheer amount of waiting time and the extreme mass fraction of the solar panels. Solar sails, even moreso.
And one more dream to kill - large open volumes are probably never going to happen. This is implied by the mathematical engineering reality of the thin-walled pressure vessel, whose minimum mass scales directly with (volume * pressure) / tensile strength. Contrary to my naive expectations, there is no square cube ratio to the structure of a pressure vessel, so every cubic meter costs mass.
Solar sails and large open spaces face big challenges, but experiments like JAXA’s IKAROS, the LightSail missions, and NASA’s NanoSail-D2 have shown that solar sails can work in space.
Isn't that a bit like saying the solar car cross-country races show that solar-powered cars can work? In both cases the 'payload' and vehicles are stripped to the barest essentials.
Solar sails with any significant mass attached to them would either need to be impossibly large, and/or operate on timescales that make ion propulsion seem like a warp drive. And that's not counting the issue of stopping when you get to your destination, which will either require some insane laser/power source already at your destination, or propellant- in which case you're back to just using that in the first place.
You’re right. Solar sails need to be massive to move anything heavy, and they take a long time to build up speed. Stopping is another big hurdle. But they’re not supposed to replace everything. They’re useful when you can’t carry fuel, like on really long missions. They’re slow, but they work for what they’re designed to do: keep going without needing fuel.
Funny, a low performance solar sail is actually a high performance sunshade, you’d actually do better with a black sunshade than a highly reflective one.
Somebody pointed out to me that IKAROS didn’t last that long (neither did its namesake), so far that’s the best rebuttal to my L1 sunshade plan but I’d imagine a second generation product could do better. People so forget that space is a corrosive environment that will wreck many materials.
(1) Build a solar sail factory on a CC asteroid and you can deliver sunshades to Earth-Sun L1 without wasting volatiles as reaction mass
(2) If you read this paper and really thought about it
https://arxiv.org/pdf/2011.07487
You’d realize that it strictly dominates all other space colonization schemes that have been proposed because it doesn’t waste volatiles for transportation. Certainly O’Neill’s ideas look infeasible in comparison (where do you get the nitrogen to fill those big airspaces? My plan for a baby Bernal sphere intended to be a luxury hotel in LEO still takes 15 starship loads of LN2 for the atmosphere)
Even Musk’s plan to colonize Mars is something that only makes sense to people who were born on a planet. If “grabby” aliens capable of interstellar travel and building such things here they might find the Earth a curiosity at best.