A hierarchy of Guidance, Navigation, and Control elements for responsive space missions

Over the past 7 years, the term ?responsive space? has come into common use, yet the definition, the implementation approach, and the key mission applications are still in flux. Most will agree that responsive implies being able to respond in the near-term to changing world events and to meet the near-term needs of the warfighter. However, the definition of near-term, especially when applied to spacecraft, is not generally agreed to. Responsive spacecraft can be created in days, as described by AFRL with their 6-day spacecraft that makes extensive use of plug-and-play (PnP) technologies, or in weeks to months, as required by ORS Tier II, through rapid integration of readily available components and subsystems. In general, for a spacecraft to be available responsively, some elements of the vehicle must be ?built-to-inventory?, such that the spacecraft can be constructed from off-the-shelf components and rapidly integrated into a launch ready spacecraft. Again, there are differing opinions as to the granularity of the built-to-inventory components: 1) complete, ready-to-fly spacecraft, 2) spacecraft busses and payloads held separately in inventory, 3) functional subsystem elements combined to create functional services, then stocked on shelves and snapped together to create a complete spacecraft, or 4) lower-level components being rapidly assembled with the aid of a configuration wizard that determines the parts that are needed to create a spacecraft that will meet specific mission requirements. In any of these scenarios, there are a few technologies, that when used together, will enhance the success of responsive space. These technologies include the use of PnP interfaces, machine parsable interface control documentation (ICDs), and the creation of self-configuring and/or re-configuring networks. This paper will address the approach explored by Microcosm, with partner HRP Systems, to have Guidance, Navigation, and Control (GN&C) components available in a hierarchical fashion, as a turn-key subsystem or services, or as the lowest level, individual components, to respond to the near-term needs of the warfighter.