SpaceX's top secret payload

The rocket and capsule were designed with a certain payload weight target in mind. What SpaceX ended up with are a rocket and capsule that are capable of transporting between 0 and X kg (where X is the maximum payload) to orbit. SpaceX obviously doesn’t design a few thousand different rockets and capsules for a few thousand different payload weights, that would not be profitable.

Now, I’m by no means a spaceflight expert but I think it’s very reasonable to assume that spaceflight is a business with stupendously high fixed costs (designing and building the rocket and capsule) and comparatively much lower variable costs [0]. What this means is that the difference in cost between a flight of the Falcon 9 with no payload (except the capsule) and the maximum payload is relatively small. You will pay a lot of money for getting the capsule into orbit either way.

Or, to put it another way, the cost of getting the first kg into orbit is very high (because it includes the fixed cost of building and designing the rocket and capsule) while the marginal cost for every additional kg is relatively small (because the variable cost is a very gentle slope).

That’s true until you reach the maximum the rocket and capsule were designed for. The marginal cost of the first kg beyond the maximum payload will be relatively large because the rocket will have to be redesigned. (Drawing a graph would make all this so much easier to understand but I hope I was sufficiently clear.)

What this means it that SpaceX saves probably hardly any money by keeping the payload as low as possible while testing rocket and capsule.

[0] Other businesses with stupendously high fixed costs and comparatively low variable costs are for example Newspapers or software developers. The first copy costs for making the first copy of a newspaper or a piece of software are very high while the marginal costs for the second copy (the additional costs the Newspaper business or software developer will have for making a second copy) are very low, compared to all the costs that came before and that are fixed (salaries, buildings, machines, …) very nearly zero.

Ugh is right. Fuel costs for a wheel of cheese would have been lost in the noise, financially speaking. This is the point SSTO advocates have been making over the years - putting things into orbit costs a lot of money, not because of the energy required, but because you throw the space ship away.