[AR] Re: Faster Space Transport? (was Re: Zubrin,

  • From: Peter Fairbrother <peter@xxxxxxxxxx>
  • To: arocket@xxxxxxxxxxxxx
  • Date: Thu, 29 Aug 2019 22:18:23 +0100

On 25/08/2019 18:13, William Claybaugh wrote:

Rand:

To first order, the cost is the cost of launch ($1300 for every pound-mass) plus the cost of the hardware (say $200 per lbm. if it is the very cheapest space hardware ever built): $1500 for every pound of structure in orbit, best case today.

Okay.

The only other economically relevant numbers are the amortization and depreciation schedules; the later should be consistent w/ the facility lifetime (ten years?) and the former a function of one’s hurdle rate...say five years for most commercial projects.

What’s it weigh?  100,000 pounds of structure to hold 500,000 pounds of propellant?  Then $150m to be paid back over five years and another $150m paid back over ten years.

Okay.

Now comes the back breaker: no one is buying any propellant because that $300m is additive to what propellant can be bought for inside an upper stage in LEO.

But let’s assume we are somehow flogging all 500,000 lbsm. every year.

Wooooah, now where does that figure come from? Why should it sell its capacity annually?

Let's try 2,500,000 lb annually. That is 5 times capacity, 50 x 50,000lb Falcon loads, one a week.

A significant increase in present flight rate, but perhaps not inappropriate if we are talking about developing regular flights to the Moon, Mars - or even just greater use of GEO.

And it's nowhere near what we would need if we are talking about building power satellites and solving the energy crisis and saving the planet...

Then the additional cost—above the cost of launching that propellant in the first place—is about $150 per lbm. of propellant.  That gets us to the “cost of goods sold” in the income statement: $1450 for every pound-mass of propellant sold assuming we are buying at $1300.

With the revised sales figure, the extra cost is $30 per lb. But I'd add another $30 per lb (pulled rather arbitrarily out of the air) for depot operating costs.

Now we add overhead and profit, typically 100% in a very well run organization; our propellant has to sell for about $2900 per lbm. using very optimistic assumptions.


Costing the propellent at 100% of sales makes the cost of propellent at the station $2,720. And I doubt anyone would pay that for a full Falcon load, though they might pay close to that for a fractional load [1] if they had no-one to share a full load with and assuming it is convenient to fill up at a depot.

But let's look at a petrol filling station (or cigarette shop). Profits on petrol are often only about 5% of sales, sometimes less - not 100%.

So if instead we cost in the profit at 100% profit on investment cost, plus 5% of sales (twice what a terrestrial filling station gets), propellent costs are now $1,485 in a depot rather than $1,300 in a second stage.

And you can fill up with ten second stage loads worth all at once in a depot, rather than fapping about chasing after ten Falcon second stages. Or buy one and a half Falcon loads without wasting half a Falcon launch. And you don't need all the hardware for in-orbit catching of Falcons and refuelling from them on your mission hardware, the station does most of that for you.

Also, I'd guess some larger frequent customers might just pay the depot $120 per lb to collect, store and distribute their propellent. Which would give the depot a simple 100% ROI.



[1] a note on half/fractional loads - I did not envisage the depot buying them at anything above full load rate. I also envisaged perhaps someone wanting a half load paying for a full load, then selling the remainder to the depot at a discount. Or someone wanting a quarter load just buying it from the depot rather than bothering with a dedicated separate Falcon launch.


The depot is, of course, called "Halfway" :)

-- Peter Fairbrother

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