> *(Their hypergolic stages used have to this capability, but they retired those 15+ years ago for performance) It's also very toxic stuff. Though I guess up i

> *(Their hypergolic stages used have to this capability, but they retired those 15+ years ago for performance) It's also very toxic stuff. Though I guess up in orbit that doesn't really matter as much. The Space shuttle used to use it (Hydrazine) for the thrusters because it's so simple and controllable. But it meant that the whole thing had to be checked for traces after landing before the astronauts could disembark.