Note on the engine math: this is a fully reusable rocket, both stages, so on a Mars missions the 31 in the booster would in theory be recovered for future launc

Note on the engine math: this is a fully reusable rocket, both stages, so on a Mars missions the 31 in the booster would in theory be recovered for future launches from the Earth. Getting the seven back from the 2nd stage, well, maybe sooner or later?