3rd Part, sort of an interlude

Find a way to pay for your dream, or it will never happen...

            I need to sneak up on this whole spaceflight, 73-Part Conquest of the Solar System crab-wise. There has to be a way to pay the way, so to speak, one that makes at least some sense. The Solar Power Bubbles I've postulated, are 100 meters in diameter and mass 3 kg/m^3 times 31,000 m^3,  ~10^5 kg or 100 tonnes of material. At a $1/kg, $1,000/tonne, that's $100,000 for structure. The things generates 100 KW, possibly a one tonne turbine @ $2/watt, for $200,000. Plus 10% is $330,000 and 111 tonnes. About 650,000 kg of air needs to be warm enough to lift 111,000 kg of stuff, 17% (actually 1/(1-.17, roughly 6/5)), or about 20% above the ambient temperature of 288 Kelvin, 58 degrees, 73 C, or 163 degrees F.

(Air masses 1.2 kg/m^3 @ STP- http://wiki.answers.com/Q/1_cubic_meter_of_air_weigh)
    

            A one km SPB would scale up two orders of magnitude; 10 MW, 11.1 million kg, $33M, but .65 billion m^3, so the air only needs to lift 1.7% of its own mass, instead of 17% (1/(1-.017), roughly 60/59), only about 5 degrees above ambient, 20 C, 68 F. People could live in the floor of the balloon and the support crew might have a hydroponic farm as part of the ballast...

            If a 1 km SPB operated more efficiently, at 2.5%, it would generate 25MW, 300 MW/day, ~110M KWH/year, $5.5M @ $.05/KHW, and pay for itself in 6 years. The 100 KW SPB are mobile and less of a hazard. They could transmit power to the ground via microwaves; the rectenna farm concept from solar power satellites. This would be very good for FEMA, the military and other remote operations. The 100 meter SPB might be less vulnerable than it seems; a big target, but also able to soak up damage.
            Mass times velocity squared is 10^5 kg*(12*10^3 m/s)^2; 100 tonnes to 12 km/s. 12*10^3 m/s divided by 24 m/s^2 is 500 seconds, T^2*Acceleration /2 is (25*10^4 s^2)*(24 m/s^2)/2 is 2.5*10^5*12 m is 3*10^6 m or 3,000 km. 3,000 SPB! 75 GW! I need 144*10^11 w/s per launch, 4*10^6 KWH, $200,000 worth of electricity @$.05/KWH, just a little less than $6/kg, $3/lb (I'll rough out an estimate of operating costs, but it's pure vapor, too!). I need 4 GWH, and have ~900 GWH per day, enough for 225 launches. At 110-plus launches per day, ~50% of capacity, that's 40,00 per year, 1.4 million tonnes or 4 million passengers...

***

            The first decade' is all about cheap access to space, and let me break it to you gently... there isn't any. The best I can work up is a scenario were costs and risks are contained enough that people can start working in space; economic activity, followed by habitats and settlement. The model I'm going with is less civil aviation or sailing ships and more railroading.

            Civil aviation is a popular model, but it ignores the fact that passenger airlines don't make money! And the sailing ship model ignores the fact that an age of sail ship carried with her al the tools and skills necessary to repair and even, in the fullness of time, to rebuild itself.

            Railroads, on the other hand, failed, a lot! They couldn't be counted on to operate, but they did tend to fail, get bought out, lay track and operate a little, and fail; a cycle that continued for a while. Like the earlier turnpike and canal systems, they were a public utility that provided transportation. Folks with wealth, status, civic hope and pride, financed them to help secure their piece of the pie, making money of the value-enhancing aspect; roads, canals and railroads made land and industry worth more. The big railroad efforts to cross North America made their money off of land speculation, only later operating off of freight and passenger service.

            I see the whole thing playing out this way-

0) Private Staged Rocketry, where we are right now.

1) Private Spaceplanes, where we will be in a few years, with same day service to anywhere in the world, as well as orbit.

2) Mass Transit To Orbit, which is basically railroading to space. I see a lot of efforts failing, and the public disillusioned with the whole thing before somebody finally makes it work- sort f like were we are with spaceflight today.

            I don't think that a space elevator will happen because there's so much debris in near earth orbit. It should work fine for the Moon and Mars, but not to GEO; we need to police our trashy skies!

            Mass Transit-

* Mass Driver @22 km altitude.

* Orbital Ring System with Jacob's Ladders from the ground, as in Paul Birch.

* Much, much later- Space Elevator.

            Services and small-scale Industry dominate this 'Middle Early Space Age', where the Early, Early Space Age was everything before the X-Prize. Services, as in Tourism and Science, and Industry, as in Energy and Materials.