If you want to build spaceships to fly around the solar system, being light still matters a lot and inflatable modules are a great idea. That’s because your co

If you want to build spaceships to fly around the solar system, being light still matters a lot and inflatable modules are a great idea. That’s because your constraint is delta-V which is expressed in terms of the mass you are moving around. More mass requires more propellant and energy… which means more mass requires more mass.