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Originally Posted by Say, it isn't that bad!
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Yeah, NASA has been going back and forth about the costs-benefits of 'active' shielding forever and a day, but they inevitably find that it ends up costing much more mass to supply the power and/or fuel. In the case of the latter article, the author ignores that, while the majority of cosmic rays are relativistic helium atoms, the majority of the damage comes from relativistic iron atoms, so the design would only give a PF of 2 against cosmic radiation. This is why the designs in the 1970s rejected active shielding in favor of passive shielding.
In addition, you need large spacecraft to have effective spin gravity and you need a diversity of capabilities and relationships among the crew to allow for successful missions. When sending people beyond the Earth-Luna system, you will probably need a minimum people of 40 individuals, just to cover enough bases, and that would not really allow for long term relationship stability. You would need around 400 people for a mission of longer than a year, as that gives a properly selected crew psychological stability.
In the case of the SM+14 spaceship, you can design a spacecraft capable of transporting 2,000 passengers and 100,000 tons of cargo for ~$20 billion. With High Automation, it would require a crew of 1,000, and it would be capable of in-situ resource exploitation, allowing it to refuel within about a month. It could get to Saturn in two years, spend six months in Saturn orbit for refueling, spend two years traveling to Earth, and spend six months in Earth orbit before repeating the process. While it would effectively end up costing $200,000 per ton of cargo delivered to Saturn orbit, when you include capital repayment and other costs, it is probably a lot more cost effective than any other design.