Launch & Flight

Getting to orbit costs about 9.4 kilometres per second of velocity change, and the rocket equation makes every kilogram of that expensive: a launcher is mostly propellant tank wrapped around a small useful payload. That single constraint explains nearly everything on this page. It is why rockets stage, throwing away structure the moment it stops earning its mass. It is why launch sites cluster near the equator and on coastlines, where the Earth's rotation contributes and the debris falls in water. It is why reusability is the industry's central argument — the first stage is most of the cost and it separates while still low and slow enough to come home.

How brutal the arithmetic is takes a number to feel. A Falcon 9 leaves the pad at about 549 tonnes and puts roughly 17 into low orbit when the booster comes back: everything else is propellant, tankage and the stage that is thrown away. Recovering the first stage is not free either — the landing propellant and the legs are payload that was not carried — and the trade is only worth making because a booster is the expensive part and refurbishment turned out to be cheaper than manufacture, which was the thing nobody could be sure of in advance. Methane engines are the current bet for the same reason: it burns cleaner than kerosene, so the engine comes back needing less work, and it can in principle be made on Mars.

What has changed in the last decade is cadence rather than physics. A single pad in Florida now flies more often than most countries manage in a decade, and a launch has gone from an event to a logistics slot. That shifts the interesting question. It is no longer whether a given launch will work — the answer is very nearly always yes, and a failure is now genuinely news — but what all this capacity is for. Most of it is currently lifting one operator's own constellation, which is a strange kind of market. The next generation of vehicles is being sized for payloads that do not exist yet, on the argument that cheap mass to orbit creates its own demand. That argument has been made before, about the Shuttle, and it was wrong then.