>>14212133Well, I was basing my idea on current supply chains.
Factory--truck->Harbour--ship->Harbour--truck->Customer
And when we're talking about shipping via land, you replace ships with trains. It works like that because it's the most cost-effective method.
Is this a bad analogy? Starship has to waste fuel on ascent, TMI, capture burn, landing and all that again, but in reverse for a return trip. If that wasn't enough, you have a lot of tanker flights to make those interplanetary trips possible.
Meanwhile, nuclear tug is optimized to travel in vacuum. No sturdy construction, no landing legs, no atmospheric engines, etc.
Also, is 800 isp, because that's how much NERVA had, not enough? That's double what the best chemical engines have.