EVER SINCE its was founded in 2002 SpaceX has been a proponent of the “fail fast; learn fast” school of engineering. And the past few months have seen some particularly spectacular failures. Two test flights of its Starship mega-rocket, in January and March, ended in fireworks as their upper stages broke apart over the Caribbean. A third test, in May, lasted a little longer, until a fuel leak doomed the rocket to an uncontrolled re-entry. In June yet another upper stage blew up, this time during a ground test.