Structural stability and structural change in a continuous two-dimensional model of a space economy are considered, and it is suggested that structural stability of flows or parametric families of flows is a reasonable assumption and secures the robustness of the models constructed. Within the format of continuous flows it is possible to characterize globally the structurally stable flows, by use of the generic theory of differential equations, and to characterize locally, the structural change of flows up to topological equivalence, by use of two-dimensional catastrophe theory.