As political and military leaders ponder the future of space operations, the time has come to frame propositions regarding spacepower. Specifically, this study seeks to answer the question, "What is the nature of spacepower?" It also tests the aerospace integration school's hypothesis that space power is simply a continuation or extension of airpower. Two points come immediately to the forefront of this work. First, spacepower is different from airpower even though both share the vertical dimension of warfare. Second, space operations have matured to a point wherein valid and unique propositions regarding spacepower are identifiable. The method used to derive these propositions involved literary research that resulted in a long list. The list evolved over three years during numerous brainstorming sessions with several space experts - most of them space weapons officers with theater and, often, combat experience - until the list was carefully refined into the 10 most salient propositions. The author deferred to Col. Phillip S. Meilinger's approach, in "Ten Propositions Regarding Air Power," of citing each proposition as a thesis statement, with supporting material immediately following. The objective of this work is to stimulate discussions and encourage those who do not yet understand or appreciate the nature of spacepower in modern warfare.