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Responsive Space® Conference 2006 Levels of Responsiveness James R. Wertz, Microcosm, 5/11/06 At RS4 there seemed to be more definitions of Responsiveness than participants. The purpose of this technical note is to give preliminary definitions of Levels of Responsiveness in terms of what it means in cost and preparation. Levels of Responsiveness for systems to be launched
Levels of Responsiveness for systems already on orbit
Discussion It is not the case that on-orbit assets are necessarily more responsive than those on the ground. One often thinks of a spacecraft as being comparable to an aircraft whose path and timing can be adjusted to meet the needs of the situation. In fact, spacecraft are much more comparable to a speeding bullet (only much faster than any rifle bullet). Their path and time of arrival can be changed, but only by a small amount and at great effort (= expense). If we are looking for coverage of a specific location either as soon as possible (i.e., after a tsunami) or at a specified future time (i.e., attack coverage), then, from a technical perspective, this is more easily and cheaply done by launching from the ground, with the launch timing and spacecraft obit selected to meet the desired objectives. For example, without a large delta V maneuver, Sun synchronous satellites traditionally used for surveillance will typically revisit a specific ground location every 3 or 4 days. Satellites launched from the ground can be timed to be there when needed and can arrive within less than an hour (or possibly a few hours if time for orbit phasing or on-orbit check-out is required).
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