The attitude that we should never do anything because its not green enough is just naive. Would you have been sitting around in 1800 and tried to stop people from explointing coal?
> They only leave with super-advanced form of green technologies.
We have that technology.
We could use nuclear energy as Nuclear Thermal rockets, we can use it as a space battery, we can use it as a nuclear reactor to drive ion enignes, we can use it on mars to make rocket fuel and so.
Ironoically envoirmentalist are partly responable that we almost use no nuclear technology anymore. They advocated for 40 years against all use of nuclear energy, and the most harmful effect is widespread misunderstanding of risks. The political deadlock about all issues nuclear make it a nightmare to deal with, and that's threw your supply chain.
A Nuclear Thermal rocket was planned to be a major part of Mars exploration when von Braun thought about it in the 60s. Robert Zubrin who planned 'Mars Direct' in the early 90s, want to use a nuclear reactor to make fuel on mars and he was strongly avocating for NTRs in the second generation. Elon Musk has said that he would want nuclear reactors on mars and NTRs in later generations.
That's exactly the advanced green technology you are looking for. After our first steps we should have moved onto that next level. Sadly it has not happened and it will take a while longer. It is currently practically impossible to devlop such a technology, unless you have direct support from NASA and other governments agencies. They themselfs have little interest in doing much in this space.
So, I think space people are happy to do it as greenly as you like, but then a whole set of regulations have to change.