Some necessary conditions for space logistics models

The Aerospace Corporation El Segundo, CA 90275 The use of near-earth space for both military and civilian purposes is expected to expand in the future. The possible cost savings and operational advantages from implementation of some type of support infrastructure is currently the focus of many studies, most of which use mathematical or logical models of the support concepts under consideration. Invariably, these evaluation models purport to show that a particular support concepr; or scrategy is besr. However, a common shortcoming in these models is that the inherent assumptions are different, and the resulting biases in the results are difficult to reconcile. Since many of these concepts are in their formative stages, this could be a serious problem. Differences in results should be caused by differences in the concepts themselves, not by modeling biases. So that results can be made consistent for all support concepts, this paper describes a set of requirements that all such evaluation models should satisfy. These requirements and other background ideas are presented in a systematic way so that they can be applied in practical modeling situations. A set of necessary conditions is provided to ensure concept neutrality and model credibility, and examples are given to illustrate these conditions.