Perhaps a lot of people wouldn't agree and I admit I'm stirring up debate a bit to see what other people think.
To me it seems if we see orbital success in the next 5 yrs, mass production of starship thereafter and SpaceX sticking to their Earth-to-Earth transport idea - this seems plausible. Airliners developed about as quick, but then again its a far harder environment - it's nice to dream.
Airliners also developed in the context of a state supported system that used regulated high ticket prices and mail route subsidies to keep the industry alive for any needed pivot to military aircraft. I don’t know that there is the stomach for such a system today.
The C-5 Galaxy can transport 127 tons and land at normal airports with at least one order of magnitude lower per kg prices. A C-17 can transport 77 tons. More importantly they can actually unload their cargo once they land. A Starship would need either special facilities or an as-yet undersigned integral crane to unload cargo.
I remember reading that that use case doesn’t really exist, especially for the US military. Stuff they need a lot of, they pre-stage, and an airborne invasion requires massive logistics, including the entire follow on ground invasion. It’s not just a matter of getting the paratroopers there quickly.
Pretty much the only airborne assaults considered still viable are airfield seizures. There is quite a bit of risk from ferrying troops to the drop zone and the time they are in the air (under canopies after exiting the aircraft). So, if the assault force can basically come "out of nowhere" and be on the ground in seconds rather than minutes, then much of the risk is reduced. Logistics can be brought in to the seized airfield in short order once secured.
I could see potential US Army interest in this concept. I think they would want the Starship to land horizontal rather than vertical for rapid disembarking though. I.e.: A ramp drops from the nose cone or similar. That doesn't seem very feasible.
While that's a good point, there are some situations they can't really pre-stage in without that in itself causing serious problems. Taiwan springs to mind.
So if some magical way is developed to have Starship land and offload it's entire cargo in <super short time>, before it's shot out of the sky, I wonder if that would be useful. Perhaps even as part of an effective deterrent strategy?
That doesn't include the cost of a vehicle that can support you for a week and re-enter and land safely, and does not include cost of ground systems to support the mission and recover you. Nor training or regulatory compliance costs. It's just the mass to orbit.
Even if Starship delivers everything promised, I doubt orbit would be within reach of wage earners. Similarly we could afford to pay for a ship to drop a few tons of rock off Guam, but going to the bottom of the Mariana trench and returning alive would be a different kettle of fish.
Every kilogram of mass added to the return trip increases the required deceleration, fuel, etc. Not cheap. At some point you can't reach orbit with the required fuel to get everything back. The Falcon 9 boosters are nearly empty when they come back. As a matter of fact, at least one of their early landing failures was because they cut the fuel load too close and ran out of fuel just before reaching the ground. Minimizing weight on the return landing is critical.
If a single one of those bridges is anything like launching astronauts to the space station in a reusable private spacecraft and launch system from american soil, it's worth buying.
