The real cost of space flight is energy, specifically:
1) The huge amount of energy required to lift mass out of Earth's gravity well.
2) The vexing practical expense of obtaining that energy in useful form (e.g. rocket fuel) for launch.
Rocketry's future will always be limited by those daunting constraints.
I'm pretty sure somewhere on the SpaceX web site they say that the fuel cost is actually a small fraction of the total cost. That's why reusable vehicles (which they want to do) even make sense.
It would be more informative to say the real price is mass, since it's the fact that you have to accelerate the mass of fuel you will use at time t up to that point that gives rise to the tragically inefficient log term in the rocket equation.
The huge amount of energy required to
lift mass out of Earth's gravity well.
... is a common misconception. The energy required to get to orbital altitude is only a tenth of the kinetic energy of orbital veloity. Yes, I'm just confirming your observation that the energy requirement is huge, but you're understating the problem, and propagating a misconception.
My point is that the insofar of the promise of space is "let's send lots and lots of stuff, especially people/food/air/water", then the fundamental economics center on energy use. Are you saying that some of the orbital velocity can be recaptured or otherwise used to offset the cost of fuel?
... I'm just confirming your observation
that the energy requirement is huge, but
you're understating the problem, ...
With regards energy use you are underselling your position by a factor of 10 when you talk about getting things 200 miles in the air. The kinetic energy required is 10 times as much. By saying what you did ...
The huge amount of energy required to
lift mass out of Earth's gravity well.
... you are:
1) understating your case, and
b) propagating a misconception (that getting out of the gravity well is the hard bit).
It would be more correct to say - the huge amount of power required to accelerate all the fuel + rocket + payload to high speed at the start.
If you could fly up to orbit at walking pace and then boost the horizontal velocity to orbit you would need very little fuel - compared to firing a big rocket for a few minutes so that the huge mass can then coast to orbital heights.
>Fuel is at present an insignificant cost of launching a rocket
Fuel is almost ALL the cost of launching a rocket. If you can arrange for me to pick up fuel every vertical mile on the way up - I can get to orbit very cheaply!
If you don't need to achieve escape velocity in the thick lower atmosphere and accelerate all those 100,000lbs of fuel to 10km/s the rocket becomes pretty trivial
I was replying to this: "Fuel is almost ALL the cost of launching a rocket."
Also, how did your hardware get out of the thick lower atmosphere? Someone paid the cost of lofting that mass.
Not much about rockets is trivial, except in theory.
Practical issues:
* heat dissipation: your fuel / oxidizer combo probably burns hotter than the nozzle material can tolerate. This needs to be tested (not for on orbit, for the first time)
* fuel supply -- it's non-trivial to design tankage and feed systems that can supply fuel and oxidizer at the rate needed, in vacuum
* propellant storage -- non-trivial unless you go for the really nasty "storable" propellants
Pretty much every piece of the problem is non-trivial.
1) The huge amount of energy required to lift mass out of Earth's gravity well. 2) The vexing practical expense of obtaining that energy in useful form (e.g. rocket fuel) for launch.
Rocketry's future will always be limited by those daunting constraints.