Spacecraft seem like one of the few cases where a small decrease in safety factor can result in a big decrease in cost. The thing about rockets is that they hav

Spacecraft seem like one of the few cases where a small decrease in safety factor can result in a big decrease in cost. The thing about rockets is that they have to lift their own fuel, so if you decrease the mass by 10% you can leave off not just the fuel needed to lift that part of the rocket, but also the rocket fuel needed to lift that amount of rocket fuel, and so on. Conversely, every additional pound for payload you get would otherwise have to be achieved by a much more significant increase in the size of the rocket.