In the previous post I considered whether we could swindle our way to the stars by way of an economic bubble. In the discussion that followed, commenter Ian Wright put a set of numbers to the idea, at the early side of the midfuture, the sort of thing that might happen by midcentury. I started to play with my own numbers in a comment, then decided to do it here as a front page post.
I'll start with a comparison point. The global airline industry is about a $500 billion business, and roughly 16,000 jetliners are in service - so each jet accounts for some $30 million in tickets and airfreight annually.
Boeing's planes (which account for about 75 percent of the total, according to Boeing) range in price from $50-60 million for 737s to $235-305 million for 747s. More small and midsize jetliners are in service than big ones, so the 'average' jet probably costs about $100 million, roughly three times the revenue it is expected to earn each year. Keep that in mind as a general rule of thumb; it happily matches the guess I made in a commentary on interstellar trade at my old website.
Now, suppose that TSTO shuttles cost 10 times as much to operate as jetliners, thus $300 million per year in revenue for each shuttle in service. (Shuttle price at the factory gate would thus be roughly $1 billion.) Let each shuttle carry 25 tons to LEO, and be good for a mission each month - say, a one week mission, from rollout to the launch pad to roll-in to the service hanger, plus a week for postflight checkout, a week for pre-mission prepping and setup, and a week for Murphy. So it costs $300 million to orbit 300 tons, a nice even $1 million per ton.
This is a thoroughly conservative estimate, by space geek standards, and yields a launch cost 'just' one order of magnitude less than current practice. If passengers can go up in airline style seating the cost of a round trip to orbit could fall as low as $250,000, a mere pittance, not much more than Virgin Galactic plans to charge for a mere suborbital pop-up.
Remarkably, the commercial satellite industry, taken in all, is a $160 billion business, a third the size of the airlines. But only a small fraction of this money goes into space: about $10 billion per year to build satellites and $2-3 billion per year to launch them. (A clean apples to apples comparison is hard to come by, but these data are at least indicative.)
Sooo ... putting this together, what might we get?
Suppose that, at the peak of a boom - or bubble - the space launch industry is a fifth the size of the current world airline industry, $100 billion per year. This is an impressively big industry, considering that the airlines go to places where people already live.
It supports an operational fleet of some 300 shuttles - more or less the fleet size at which you can spread out development cost across a decent sized production run, and get some real production efficiencies going. Together they can loft 90,000 tons into orbit each year; call it an even 100,000 tons per year, for luck. In the course of a decade, a million tons, at total cost of a trillion dollars.
(Those of you with suitable keyboards can substitute the Euro symbol; at this level of approximation the exchange rate makes no matter.)
But in the satellite industry today, space launches account for less than 2 percent of revenue. If you scale our hypothetical space-boom industry accordingly, it is about a $5 trillion industry, or about 8 percent of current world GDP.
Bzzzzzz! No sale. This does not pass the smell test, short of alien invasion scenarios. We will have to goose these numbers downward.
Commercial satellites today cost about five times as much to build as they do to launch, but they are packed with very expensive electronics, while our much heavier payloads are mostly (relatively) cheaper structural fabrications, supplies, fuel, and the like. Let these cost about as much at the factory gate as launching them does, $100 billion for 100,000 tons of hardware and supplies - an average cost of $1 million per ton, close to what an airliner costs.
The direct cost of our space effort - building stuff and launching it Out There - is now $200 billion per year. The satellite industry spends about 12 dollars on earthbound goods and services - everything from surface stations to home dish installers to marketing - for every dollar it spends on space launches and hardware. Let our space industry spend only twice as much on what stays down as what goes up, thus $400 billion. Thus the total operating cost of the industry is now $600 billion, one percent of current world GDP. This makes it four times the size of the current satellite industry and rather larger than the current world airline industry.
In the course of a decade we rack up $6 trillion in expenses, money on which the investors expect a handsome return, say $400 billion per year on top of operating costs. (Which makes it a trillion dollar industry, if it expects to return a rather modest 7 percent clear return on investment.)
For this we get, over a decade, a million tons lofted into space, including structures and equipment, supplies, propellant, everything. Suppose that 20 percent of that is station or hab facilities, thus 200,000 tons. The ISS has a mass of 300 tons and a crew of six, one per 50 tons, so let us say that we have 4000 people in space.
Getting all of this ginned up and ready to go - for example, developing and testing those shuttles - might take another decade, so we're looking at 20 years, give or take, from inception to the point where we have a million tons and 4000 people in space. But we don't charge extra for this; the development cost is folded into the overall cost as given above.
Ian Wright in his comments starts with pretty similar numbers and ends up with a lot more people in space - a million - which merely shows that small differences in input assumptions can yield big differences in end results. But even 4000 people is a meaningful down payment, the germ of a space-living community.
(As another interesting reference point, Robert Heinlein back in 1949 gave $30 per pound as the Earth-Moon shipping charge, equivalent to $67,200 per ton. Allowing for inflation between 1949 and 2009 that is equivalent to a shade under $600,000 in current dollars. That's for getting to the Moon, not just LEO, but LEO is the toughest part of the trip, accounting for perhaps half of the total cost, $300,000 per ton, similar to Ian's estimate and about a third of mine.)
To get this, or something on roughly the same order, all you need to do is to persuade the world to pony up about one percent of its income for a decade or so, and build an industry comparable in size to the airline, automotive, or tech industries. Possible? Yes! Challenging? Very!
Related link: My old website post on Interstellar Trade.
The image is, naturally, swiped from Atomic Rockets, just above the Heinlein passage cited above.