I mean practical in that there's no exotic science required. Everything required we have ideas on how to accomplish now, and the big issues are making it cost effective.
And as for the 100 trillion budget, if you're launching from the earth, sure. Geologists are pretty sure the moon has plenty of materials useful for building stuff. We've already built mass drivers, and the physics for building one that could launch raw materials from the moon are perfectly sound.
Yes, we need to figure out mining materials and building stuff in space. But we're going to have to figure that out anyway if we want to survive as a species in the long term, and there's plenty of advantages in starting to figure that out now, especially since we're staring down the barrel of a gun vis-a-vis climate change.
And as for the 100 trillion budget, if you're launching from the earth, sure. Geologists are pretty sure the moon has plenty of materials useful for building stuff. We've already built mass drivers, and the physics for building one that could launch raw materials from the moon are perfectly sound.
Yes, we need to figure out mining materials and building stuff in space. But we're going to have to figure that out anyway if we want to survive as a species in the long term, and there's plenty of advantages in starting to figure that out now, especially since we're staring down the barrel of a gun vis-a-vis climate change.