In the fourth year after its initiation and after a great deal of deliberation among opposing elements within NASA, Surveyor was curtailed to an Apollo-supporting project. Lunar Orbiter, on the other hand, was designated from the beginning as a single project to obtain data for Apollo. In this kind of an anyalsis one is confronted immediately with the question of what constitutes success in a program or project. There is no universally accepted set of criteria for measuring the success of research and development undertakings or the performance of those who manage them. Obviously a great deal hinges on such nonquantifiable factors as the degree of technical difficulty, the relative point in technological development at which a project is undertaken, the management philosophy guiding the sponsoring agency, and the overall environment in which a project operates.
Comparisons based on the ratio of final costs to initial estimates are hazardous.
There are many reasons both for and against overoptimism at the various levels where estimates are made, by the contractor, the field center, the NASA program office, or senior levels of NASA management. All such factors have a bearing on the reliability of cost estimates and should be taken into consideration when using costs as a measure of performance. In these two projects, the United States acquired means of operating in space with both machines and men. The unmanned vehicles preceded the manned vehicles. Surveyor was the first long-lived NASA vehicle to land on and reduce uncertainties about the surface of a large body of matter other than the Earth.