The use of humans to service satellites designed for servicing has been adequately demonstrated on the Hubble Space Telescope and International Space Station. Currently, robotic on-orbit servicing technology is maturing with risk reduction programs such as Orbital Express. Robotic servicing appears to be technically feasible and provides a set of capabilities which range from satellite inspection to physical upgrade of components. However, given the current design and operation paradigms of satellite architectures, it appears that on-orbit servicing will not be heavily used, and, as a result, is not likely to be economically viable. To achieve the vision of on-orbit servicing, the development of a new value proposition for satellite architectures is necessary. This new value proposition is oriented around rapid response to technological or market change and design of satellites with less redundancy. Nomenclature a phase = semimajor axis of the phasing orbit for the servicer a target = semimajor axis of the target satellite orbit CP Ser = servicing cost penalty C op = cost of satellite operations C sat = cost of satellite development k servicer = no. of phasing revolutions of the servicer k target = no. of phasing revolutions of the target satellite N Trans = no. of transponders P markup = markup for serviceable satellite RIFR = interest free discount rate RINF = inflation rate RINS = insurance premium RIRR = internal rate of return t H = expected end-of-life year of the satellite t k= decision year t 0 = initial launch year X 0 = initial value of a GEO satellite communications market V phase = velocity change necessary for servicer to adjust its phase to match target satellite V proximity = velocity change necessary for servicer to adjust to proximity operations at target satellite # = initial angular separation between servicer and target satellite

Often shifts in context, such as changes in budgets, administrations, and warfighter needs, occur more frequently than high-cost space-based system development timelines. In order to ensure the successful development and operation of such systems, designers must balance between anticipating future needs and meeting current constraints and expectations. This paper describes the application of Multi-Epoch Analysis on a previously introduced satellite radar system program case study, quantitatively analyzing the impact of changing contexts and preferences on "best" system designs for the program. Each epoch characterizes a fixed set of context parameters, such as available technology, infrastructure, environment, and mission priorities. For each epoch, several thousand design alternatives are parametrically assessed in terms of their ability to meet imaging, tracking, and programmatic expectations using Multi-Attribute Tradespace Exploration. While insights on tradeoffs are discovered within a particular epoch, further dynamic insights become apparent when comparing tradespaces across multiple epochs. The Multi-Epoch Analysis reveals three key insights: 1) the ability to quantitatively investigate the impact of "requirements" across many systems and contexts, 2) the ability to quantitatively identify value "robust" systems, including both passively robust and changeable systems, and 3) the ability to quantitatively identify key system tradeoffs and compromises across stakeholders and missions.

Public reporting burden for the collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to a penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number.

In this short paper, the Responsive Systems Comparison (RSC) method is introduced. RSC is a structured method for collecting information and conducting analysis to characterize a wide variety of possible futures in order to enable the comparison of the performance of proposed systems in those futures. A case study uses the RSC to analyze a satellite radar system. The needs and expectations of a user community for such a system, the context it will operate in, and its technical basis are determined both at the present time, and with possible changes over the next 15 years. This information is used to set up an analysis that should be able to highlight systems that will deliver value under a wide variety of future situations. The case study illustrates the practicality of the method, and provides lessons for improvement and implementation.

No abstract