Outer space activities have entered a period of continuous expansion through privatization, tourism, military and other efforts, simultaneously increasing the concern for potential environmental impacts caused by the increased amount of space operations on the Earth, space and other planetary ecosystems. With an interdisciplinary approach including a strong technical focus, assessing environmental pollution on the earth, space and planetary environments, as well as a strong legal focus, determining potential legal requirements for the conduct of procedures assessing environmental impacts of a proposed action previous. The analysis is based on the three largest emission sources of spaceflight: (1) Launching- and Flight-Stage Pollution, including rocket propulsion emissions, hazardous materials, and air, water, soil contaminations inter alia, (2) Space Debris, and (3) Planetary Contamination, including backward and forward pollution on earth and other planetary systems. The definition, aim, and structure of terrestrial Environmental Impact Assessment procedures are discussed, including the relevant national, European and international legal basis and application. The thesis continues by evaluating legal norms and regulations governing the use of Environmental Impact Assessments for outer space projects. This thesis seeks to assess if national, European and international legislation and guidelines establish a requirement for the conduct of EIAs including the establishment of prevention and mitigation measures for environmental consequences arising from the use and exploration of outer space. The legal and technical frameworks are further assessed in the case study of NASAs Mars 2020 Mission and the therefore published Environmental Impact Statement. Recommendations are given with respect to widening the legal application not only on the requirement of assessing potential harm by a space mission but also in establishing obligations on the oversight of compliance with prevention and mitigation measures for the minimization of environmental consequences set up in an Environmental Impact Statement.