Outer space, including the Moon and other celestial bodies, shall be free for exploration and use by all Nations

—United Nations Treaty of 1967

Although NASA is the best-known space organization in the world, it is not the only one. The U.S. military has an active space program that existed even before NASA was formed. Most modern military space ventures center around ballistic missiles and data-gathering satellites. These are unmanned projects. There are also many foreign governments with space programs. Chief among these is the Russian space program operated by an agency called Rosaviakosmos. The Russian agency continues the program begun by the Soviet Union decades ago. For about half of the twentieth century the Soviet Union engaged in a bitter Cold War rivalry for space supremacy with the United States. The...