The following was posted on plebbit during an AMA with Donald Trump during the election:
To summarize the benefits of the proposal upfront:
can be completed within 2-3 years (less than one term in office)
costs up to $30 trillion but generates $18 trillion in revenue per year upon completion (costs are very, very conservative high end estimates as you will see later and ~$5T is more reasonable but I don’t want to oversell)
at the end of 4 years, you have a net profit of $6T plus $18T in revenue every year thereafter
In other words, in your final year as president you can:
pay off the national debt
cut taxes to 0% across the board
maintain all government spending without any further taxation
start cutting a check to every American every year for $50,000
The project outline:
Launch 100,000 tons of material into GEO using the Falcon Heavy at a cost of $1000/kg for total rocket costs of $100 billion
This 100,000 ton of material is used to build a capturing device for payloads sent into space with a rail gun (the simplest idea, but not the best, is to think of it like a big fluffy mattress in orbit - you can hit the mattress with your rail gun payloads to bring them to rest with respect to your target in geosynchronous orbit)
To give you an estimate of the railgun costs, high performance maglev tracks cost about $100 million per mile and we need 100 mile long track to keep the gee loading of launches within human survivability. That’s $10 billion, but adding a factor of 10 call it $100 billion for our launch device
The purpose of this system is to launch 17TW/s of solar power capacity into GEO.
Here, I have used NASA’s estimates of material costs from 2012 with an economy of scale gained from 500MW production (34,000 times smaller than the actual scale, therefore grossly inflated costs on a per unit basis)
$400 million material costs (solar panels, wireless transmission, mirrors, etc.) per 500 MW translates to $13.6T for 17GW of power.
To maintain the orbit of our capturing device, we have to provide thrust equal and opposite to whatever is imparted on the arriving payloads. NASA uses 25 kilogram ion thrusters that produce 90 mN of thrust which is the same as requiring 500 second burn time to correct for its own capture. A practical launch sequence for the project is something like this:
Send up 500 MW of solar power generation capacity and 25,000 ion thrusters (what 500 MW can power)
It takes 50 days for these 25,000 ion thrusters to correct the orbit of the station
Every doubling of power output thereafter takes only 50 days and we need 16 doubling cycles to reach 17TW or ~26 months
Finally, the weight of the wireless transmission capacity is roughly equal to the weight of solar panels + mirrors + structural support, etc., so we need one last doubling cycle to send up the necessary equipment to beam our 17TW of power back down to Earth.
The net result is that we’ve paid for 850 million ion thrusters at a cost of $10,000 a piece or $8.5 trillion on top of our $13.6 trillion in solar panels / mirrors / wireless transmission / etc.
If you employ 10 million people at $100,000/year for 3 years as part of the project, that costs a further $3 trillion
net total is ~$26T
The global average electricity cost is about $0.12/kwh so 17TW/s power generation is equivalent to $18T in revenue.
Some practical notes:
material costs can be expected to drop ~95% from an increase in production scale factor 34,000 so our material inputs of $22 trillion is more likely close to $1 trillion
I’ve calculated thrust requirements based on a vertical launch from Earth, but the more practical design is an angled launch so that our projectile arrives with a substantial portion (90%) of its orbital velocity, thereby reducing thrust requirements 90%
We recapture ~30% of salaries paid ($3 trillion) in taxes plus economists put the multiplier effect of infrastructure programs at around 3 which makes them approximately revenue nuetral (i.e. further recapturing 30% of 3x your expenditure) without considering the benefits of the project in the long run
we can build an orbital ring to support wired transmission of power back to Earth for less than the cost of sending up wireless transmission capacity
Therefore the more reasonable cost estimate is something like $1.1T (material) + $1T (GEO capture device + railgun launcher) + $3T (human labor at high salaries) but all of this should be considered revenue neutral due to stimulative effects.
