How does Starship achieve significantly lower dollars-per-kilogram launch costs?


I’ve heard numbers such as $200/kg to LEO for Starship. I’m trying to understand this.

I figure that the Falcon Heavy is already about 96.5% reusable (at least 27 of 28 engines are reused). Based on the recent Roman telescope deal ($255M), Falcon Heavy costs $4000/kg.

How is Starship, which is basically only 3.5% “more reusable”, going to cost 20X less? Is methane massively better than RP5? Is stainless steel way better than aluminum? Is it because it’s taller? Fatter? Is it the tower catch? Is it because the booster returns to the launch pad instead of landing on a drone ship?

In: 3

It reduces costs through economy of scale. It is a very large rocket, with a smaller cost to turn around and launch again. It’s like comparing to cost to drive a car across country against riding in a bus/train/plane. Getting 300 other people to agree to go with you on the train is a huge economy of scale impact.

It doesn’t. Not yet.

There’s a concept called “economy of scale”. The more stuff you produce, the cheaper it is. If you hired a guy to custom-build you a sports car, it would be crazy expensive. He’d have to know what he was doing (so highly skilled labor), he’d have to design the thing, and he’d have to make a lot of the parts himself. It’s much, much cheaper to just buy a Corvette. Those are produced on an assembly line in huge quantities, and tens of thousands of them are sold each year. The costs are spread out amongst all the buyers.

Right now, space travel is closer to the “hire some people to custom build it by hand” end of the scale, rather than the “buy one from the dealership” end. Musk hopes that Starship will lower the costs enough so that governments will buy more of them. And then private companies will buy some. And gradually the cost will come down, as they set up factories to mass produce them.

Elon also talks about Starship being “rapidly reusable”. It is possible that despite being over 90% reusable, the cost of operating the drone ships and faring recovery ships is significant. But if you use off-shore platforms for launching Starship then you will still need ships to get payloads and fuel out to them, so either way you need to operate a fleet of ships.

Falcon9 and Falcon Heavy also jettison their fairings once they leave the atmosphere whereas Starship takes them all the way to orbit. That has to eat into Starship’s payload ratio.

I do think it would be interesting to see some kind of detailed breakdown of where all money goes when a customer buys a launch. I would be interested in hearing what other people think about this.

For Starship the key thing is achieving a “fully and rapidly reusable” second stage. At this time no second stage is reusable.

Methane engines will combust “cleaner” with RP1 you have to worry about coking and soot in the engines, Merlin engines on the Falcon 9 need to be cleaned between launches.

Stainless steel is cheap, it has better strength and other properties the temperature ranges needed for a fully reusable conditions. (Cryogenic temperatures and reentry heating)

When you have a bigger rocket a proportionally smaller amount of the mass you’re lofting to orbit is “rocket” when you increase the diameter of a cylinder the volume on the interior increases much more rapidly than the surface area does.

You have a right to be puzzled. This $200/kg to LEO number is yet to become real. Economies of scale will bring down Starship launch costs, but to go from $4,000 to $200 is quite the leap.