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Say you want to build something new, something that is beyond the bounds of what anyone has ever built before. In this case, a rocket that has more thrust than any built before. The basic mechanics say that it is feasible, so you start to work the details. You find the limit of knowledge in all kinds of directions, and determine which limits you can definitely build the rocket within, and which ones you will need to exceed. As the world's most powerful rocket, perhaps it will exceed current bounds of knowledge about things like material performance and turbulence under extreme temperatures and pressures. Anything built outside of currently-known parameters might fail, so you design as much of the rocket as possible to operate within the limits of current knowledge. Some of those limits turn out to be feasible to push in a laboratory. So you build and conduct experiments on those parameters, record the results, and design your rocket accordingly. But for some parameters, the lab experiments required to test them are incredibly costly. Especially for parameters that vary strongly with scale (like turbulence), a system with the size and energy of the world's largest rocket can only be predicted by an experiment with the size and energy of the world's largest rocket. Say it costs a billion dollars to build and launch your new rocket, but it will operate with ten unknown parameters, each of which will cost 200 million dollars to individually test on the ground. You could spend two billion dollars on experiments, then one billion dollars on a rocket you're confident will work. This is more-or-less the model that NASA used for developing the Space Launch System: do as much science as necessary, ask Congress for as much extra time and money as the contractors say they need, so they can be extremely confident that their new biggest rocket will work perfectly the first time. NASA doesn't like launching rockets that they don't know will work, because Congress doesn't like when rockets they paid for blow up, and NASA depends on Congress for all of their funding. However, for the same money, you could build your rocket best-guess within the known unknowns and fly it. It's likely to blow up, because you guessed on ten unknowns. However, if the results of the flight allows you determine some of the parameters with greater confidence than one billion dollars in ground experiments, then it was worth the while, and you re-design your rocket according to the newly-understood parameters. You can do this three times for the cost of building the experiments and flying once. That's a decent chance at learning the parameters, and as a bonus, you get to practice building and flying the rocket, productively employing all of your staff and facilities. That's more-or-less the model that SpaceX is developing Starship on, and previously Falcon 9. Blowing up prototype rockets only costs SpaceX time and money, and as long as it costs less time and money than running ground experiments (and keeping their production and launch crews on retainer, and maintaining their facilities between rockets), they're saving money by launching rockets they expect to blow up. |