ELI5. If the weight of rocket fuel is so important, why do SpaceX boosters waste a ton of fuel landing themselves?
In: Engineering
The most expensive part of a rocket is the rocket, not the fuel.
Rocket A can’t be reused. It’s slightly smaller and slightly cheaper.
Rocket B is designed to be reused. It’s bigger and more expensive to accommodate the fuel needed to recover itself. It will also cost money to recover and refurbish Rocket B into launch condition.
But the calculus is that if Rocket B+2x B-amount of fuel+Recovery&refurbishing costs for Rocket B is cheaper than 2xRocket A+2xA-amount of Fuel, then two launches with Rocket B will be more efficient from an economical standpoint.
The value of Rocket B will degrade somewhat with each launch, but maybe it can handle 5-10 launches with lower priority cargo each run (nobody wants to launch an expensive satellite, or people for that matter, with a potentially unreliable rocket. But if the major cost of the launch is just getting that amount of weight into space then it’s fine to gamble on whether it will make it or not).
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