Environmental laws and regulations are among the fastest evolving areas of law, particularly within the EU. Recently updated regulations such as ESA's own "Requirements on Space Debris Mitigation for Agency Projects" and France's "Space Operations Act" impose regulations on environmental impact of space activities. The European Space Agency, with its Clean Space initiative, devotes increasing attention to the environmental impact of its activities through the implementation of specific technology roadmaps. This paper will describe the activities on-going, planned and proposed in the frame of branch 3 and branch 4 of the Clean Space Initiative. Branch 3 aims at developing technologies required for managing the end-of-life of space assets and Branch 4's objective is to develop key technologies for active debris removal. Two main categories of technologies are studied for branch 3: technologies for un-controlled re-entry and technologies for controlled re-entry. Technologies under development for branch 4 are focused on un-cooperative target. The paper presents the technologies currently studied by ESA for meeting Clean Space branch 3 and 4's objectives.