Today Super Heavy is a piece of pure electric-guitars-and-screaming-eagles space awesomeness, from the gorgeous purple exhaust plume full of shock diamonds, to the grace with which it descends on a single swiveling column of flame until the rocket comes to rest on the chopsticks that catch it.

The fact that SpaceX seems to have had less trouble with this vast booster than the simpler upper stage was one of the big surprises of the flight test campaign. While Super Heavy had some early engine failures on the first two flights, these were ironed out quickly. The fifth and seventh test flights demonstrated a successful return of Super Heavy to the launch pad, and the booster from that second catch was then re-flown two flights later.

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The second stage of Starship, confusingly also called Starship, is where SpaceX has struggled. The problem is mostly one of size. In order for Super Heavy to fly back to its launch site, Starship-the-rocket has to stage very early, which pushes a lot of mass and propellant into the second stage. That stage is about as tall as the Space Shuttle and its attached fuel tank put together, and when fully fueled, nearly as heavy as the entire Space Shuttle stack was when it sat on the launch pad.

Keeping this hunk of spacecraft intact and controllable during re-entry requires large control surfaces and a capable heat shield. But for these elements to be re-usable, they have to be sturdy, and ‘sturdy’ in an aerospace context usually means so heavy that it eats through all your available payload.

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The nightmare scenario for SpaceX is one where making Starship robust enough to survive repeated atmospheric entries leaves it too heavy to carry useful payload. This seems to be what happened with V1. That first iteration of Starship was supposed to deliver 100 tons to low earth orbit, a claim Musk later walked back to 45 tons, then ultimately 15 tons, less than the payload of the Falcon 9. The V2 version of the rocket (a horrible version number to use in rocketry, just saying) managed to lift 35 tons to near orbit, but was also prone to explode, accelerating the shift to the new design that launched on Friday. Starship V3 has incredible new engines and looked peppy on its maiden flight, but it’s not clear how much mass will have to be added back to the rocket before the latest design either stabilizes or gets ditched for an even more ambitious V4.

Put simply, SpaceX is in a race to see whether it can improve performance in the Raptor engines faster than the upper stage of Starship gains weight. The real test for the program will be the first capture and re-flight of an upper stage, because the economics of launch cost are sensitive to just how many times that upper stage can fly. If it turns out a Starship upper stage is only good for a flight or two, the rocket will remain groundbreaking, but cannot meet its more transformative goals.

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How often will Starship launch? Getting a credible answer is hard because the SpaceX IPO hinges on preposterous numbers that the company can’t disavow yet.

The lower limit to launch cadence is set by SpaceX’s contract with NASA for a lunar lander, which the agency calls the ‘Human Landing System’. HLS has to be refueled from an orbiting depot Starship to get to the Moon, and filling that depot will involve launching a large number of tanker Starships over the span of a few months. How many launches that will take is unknown; I think people would be surprised to see it happen with fewer than ten launches, or more than thirty. Assuming that a fuel depot can hang around in orbit for six months, that implies an operational tempo of about one launch per week, from at least two different launch sites (so that a pad explosion at one won’t ruin the whole campaign).

This would be an ambitious but achievable cadence for Starship, particularly if the tanker Starships didn’t have to be reusable, and could be made without a heat shield or control surfaces. Just how much time SpaceX has to reach this cadence is an interesting question, since right now NASA and SpaceX are locked in a game of chicken around who can commit to the least realistic timeline. But it probably has to get in gear by early 2027.

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Finally, there is the launch cadence SpaceX actually targets in their S-1, a million metric tons a year to Earth orbit. That frankly preposterous figure implies 25-30 Starship launches a day, with the exact number contingent on how much payload the final version of the rocket can carry. This would be the flight rate of a small regional American airport like Chattanooga or Sioux Falls, except that instead of turbojets SpaceX would be launching skyscrapers full of liquid oxygen and methane from a constellation of launch pads, each one handling multiple launches, catches, and re-stackings in every 24 hour period.