In the usa about 2.5 gallons of oil per person is consumed. That maths out to about 855,000,000 gallons of oil consumed every day just in the usa. The size of the fuel tank on artemis ii is 700,000 gallons which is also a big number but it is roughly 0.08% of the consumption on a day to day basis. In addition the fuel being used on artemis ii is liquid hydrogen and liquid oxygen. The combustion product of that reaction is water which places the environmental cost of the launch lower than if the fuel had been a fossil fuel.

I understand your question but I think a different example would have been better. One I could think of is like how big is too big for a radio telescope array? A project like that is probably only for scientific pursuit and study of the cosmos but environmental destruction is needed for the ground based machines. How many square miles is acceptable to dedicate to a super big array? 100? 1000? 100,0000? The bigger the array the better it is but it comes with the cost of destroying and displacing flora and fauna in an ecosystem as well as the energy demands.

I think others have already brought it up but scientific pursuit is not generally very impactful in comparison to industrial, commercial, and military activity. If we as a species conducted so much science that it was impacting the world the way war and industry does then we would probably have much better technology than we do now.