Should private investment play a larger part in the national space program? Some people see increased opportunities for private enterprise in producing goods and services related to space, and hold that one purpose of the space shuttle and the international space station should be to foster such private activity. They also contend that commercializing space activities will enable the government to pursue the traditional objectives of the national space program-science, exploration, and national security-at less cost, because private investment will make available a broader array of less expensive goods and services. While direct federal expenditures to promote private investment in space activity are small relative to total federal spending on space, a large part of the government's nonmilitary spending on space is partially justified as contributing to the commercialization of space. This study analyzes the status of private investment and its relation to federal policies and programs in the markets for: Space launch services provided by large unmanned rockets, or large-capacity expendable launch vehicles; Land remote sensing data gathered by satellites-for example, photographs that are used to produce information for agriculture and forestry assessment and forecasting, geological surveys, planning land use, mapping, and environmental monitoring; and Science and technology related to the processing of materials under conditions of microgravity in space, including both the results of experiments and the orbital facilities necessary to conduct them. The three markets considered do not include all potential commercial activities related to space. The study does not include satellite communications services, which have become the most successful private business relating to space, nor does it consider several new prospects such as satellite navigation and positioning services. The focus on three markets does, however, allow examination of most of the general issues related to federal policy encouraging the commercial use of space. The terms "commercial space," "commercialization of space," and "space commercialization" are defined in this study as private investment in space activities. They do not include traditional contracting between government agencies and established aerospace companies, nor the technologies randomly spun off from the public space program to private industries. Commercial space activities focus ultimately on private markets beyond the government or, at a minimum, involve significant private capital at risk. The products and services brought to the market by commercial space producers are designed, developed, or produced by the private sector itself, rather than by the private sector under the oversight of government managers.