They're also the folks working on the largest co2 -> methane converters in the world. Because that's how they'll need to make fuel on Mars, and no one else on earth wants to fund an expensive technology to replace an inexpensive gas pumped from the ground. By definition, these reactors will have to be capable of producing enough fuel for a rocket in order to be fit for purpose. That opens the door for carbon neutral operation. It's tough to imagine a greener rocket than a fully reusable one that's carbon neutral running on methane. Sure beats spewing hypergolics or solid rocket fuels.