SPACE is the common property of mankind. Traditionally, access to common property resources such as the oceans has been open and free. This is appropriate for resources that are plentiful. At first glance, space appears to be not only abundant but infinite. However, future demand for space resources may soon make them scarce in the sense that an allocation mechanism will be needed for their efficient utilization. Satellites already perform traditional and new services using outer space resources, and plans for industrial ventures in space are under way. Space activities compete with more earthly activities for use of the scarce electromagnetic spectrum. This paper demonstrates how the general principles of efficient markets easily can be extended to space resources. In fact, the market mechanism is particularly well suited to achieving efficient use of these resources given the difficulty for a central authority to obtain the necessary information. The paper is inspired by two seminal articles by R. H. Coase on the organization of economic activity.' Our application is one of many