The paper develops four alternative core-technology advancement specifications, one for each of the four strategic goal options for government investment in human space flight. Already discussed in the literature, these are: Explore Mars; Settle the Moon; accelerate commercial development of Space Passenger Travel; and enable industrial scale-up of Space Solar Power for Earth. In the case of the Explore Mars goal, the paper starts with the contemporary NASA accounting of ?55 Mars-enabling technologies. The analysis decomposes that technology agenda into technologies applicable only to the Explore Mars goal, versus those applicable more broadly to the other three options. Salient technology needs of all four options are then elaborated to a comparable level of detail. The comparison differentiates how technologies or major developments that may seem the same at the level of budget lines or headlines (e.g., heavy-lift Earth launch) would in fact diverge widely if developed in the service of one or another of the HSF goals. The paper concludes that the explicit choice of human space flight goal matters greatly; an expensive portfolio of challenging technologies would not only enable a particular option, it would foreclose the others. Technologies essential to enable human exploration of Mars cannot prepare interchangeably for alternative futures; they would not allow us to choose later to Settle the Moon, unleash robust growth of Space Passenger Travel industries, or help the transition to a post-petroleum future with Space Solar Power for Earth. The paper concludes that a decades-long decision in the U.S.--whether made consciously or by default--to focus technology investment toward achieving human exploration of Mars someday would effectively preclude the alternative goals in our lifetime.