This paper proposes a new approach of the technical, organizational, and political structuring of space activities. Drawing from the “linked ecologies” model theorized by Andrew Abbott, we take the development of the program Copernicus Earth Observation/GMES (Global Monitoring for Environment and Security) as an analyzer of the process of establishing a specific European space ecology. Conceived in the late 1990s by the European Union (EU), the European Space Agency (ESA) and other institutional actors, GMES aims at aggregating collections of data on a variety of environmental and human phenomena through satellite and ground observation systems. With Galileo (the global navigation satellite system), GMES is promoted as a tool for “implementation” of EU policies and it illustrates the strategic ambition of the EU to assert itself as a space power. We show how, through GMES, a European space community is being structured, and not only an intergovernmental one (under the jurisdiction of ESA). From our point of view, the challenge lies in understanding the division of labor organized throughout the 2000s, and the resulting territorial demarcations : on one hand, the European Commission is in charge of the “political governance” and the GMES budget ; on the other, ESA provides technical and scientific expertise to implement and operate satellites and ground segments. Actors from both the ecologies of the European space community and the European political system invent a modus vivendi. We analyze how these fields of action are limited by and within a specific inter-ecological settlement. Here, the definition of a “market of downstream services” designed to exceed the support of public investors (traditional supporters of space activities) is a major political issue for the European authorities. In the end, we observe a relatively clear separation of these spheres of competence and activity within the boundaries of the emerging European space ecology : the technical, administrative implementation and policy-making practices may interact, but they do not dissolve into an undifferentiated pattern of activity.