Measuring the Value of Flexibility in Space Systems: A Six‐Element Framework

Nilchiani, Roshanak; Hastings, Daniel E.

doi:10.1002/sys.20062

Cited by 79 publications

(57 citation statements)

References 12 publications

(6 reference statements)

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“…Galileo was a National Aeronautics and Space Administration (NASA) satellite built to explore Jupiter and its moons 16,17 . The satellite initially was intended for launch aboard a space shuttle in 1985, but due to launch delays and the 1986 Challenger disaster, the mission did not launch until 1989 aboard space shuttle Atlantis.…”

Section: Galileomentioning

confidence: 99%

Case Studies of Historical Epoch Shifts: Impacts on Space Systems and their Responses

Beesemyer

Ross

Rhodes

2012

AIAA SPACE 2012 Conference &Amp; Exposition

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Developing space systems often comes with high costs and long development times, resulting in significant investment. Space systems can take large amounts of resources to design, build, test, field, and operate, and can be required to operate for long periods of time in very harsh environments.These environments may be dynamic and possibly unanticipated during design and development. Given the large investment, space systems are expected to succeed in spite of encountering perturbations (disturbances or epoch shifts) that could impact their value delivery. The concept of value sustainment is proposed as the ability to maintain value delivery in the presence of such perturbations. Of the two types of perturbations, responses to epoch shifts (i.e. shift in context and/or needs) are investigated in this paper. The construct of Epoch Shift-Impact-Response-Outcome is proposed as a way to characterize and analyze historical system responses to changing operating contexts and needs. Four different historical cases, Iridium, Globalstar, Teledesic, and Galileo, and associated epoch shifts, are described, providing insights into how systems can respond to perturbations and what system characteristics aid in that process. The concept of ilities is briefly introduced, linking the system response to qualities that make a system successful. The epoch shift case studies, along with the corresponding displayed ilities in these systems, may provide a useful framework for future study. A broad survey of past systems characterized in this way may provide insights into the types of dynamic uncertainties that pose risks to such systems, as well as patterns of response (i.e. ilities) for such systems, in order to enhance the ability to intentionally design for value sustainment across dynamic operating environments in the future.

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Section: Galileomentioning

confidence: 99%

Case Studies of Historical Epoch Shifts: Impacts on Space Systems and their Responses

Beesemyer

Ross

Rhodes

2012

AIAA SPACE 2012 Conference &Amp; Exposition

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“…In addition to improvements in these traditional performance features, they also call for more flexible space systems that could enable them to better manage the numerous uncertainties associated with space systems. Space systems actually often fail to meet new market conditions, to adapt to new applications, to incorporate the latest technologies and more generally to adapt to changes that may occur during their lifetime, in particular once they are launched (Nilchiani, 2005), which justifies the need for more flexibility. Space systems flexibility may include for instance the possibility of maintaining or servicing space assets once launched in case of unanticipated failure or degradation.…”

Section: C1 Needs For Future Space Systemsmentioning

confidence: 99%

“…The utility derived by customer from flexibility cannot be evaluated as such, as it can be done with traditional performance parameters. The various forms of flexibility are relative (Nilchiani, 2005). Therefore, for each mission and for each form of space assets flexibility investigated, scenarios that best represent the potential value of this type of flexibility need to be defined with the decision-maker.…”

Section: C2 Implementationmentioning

confidence: 99%

Assessing the Fractionated Spacecraft Concept

Mathieu

Weigel

2006

Space 2006

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In the traditional approach, spacecraft are tailored to each mission and are associated with high risks and costs and long cycles. Moreover, once launched, their flexibility remains limited. The concept of spacecraft fractionation could enable manufacturers and users to decrease these risks and costs and to increase space systems flexibility. Fractionation transforms the traditional monolithic spacecraft into a network of elements: a free-flying payload module is supported by free-flying modules that provide the payload with power, communications, etc. Thus modules could be maintained, exchanged, and reused once launched. Furthermore one could imagine developing a whole on-orbit infrastructure made of standardized modules that could support different payloads.This thesis investigates under what conditions fractionated spacecraft could be worthwhile alternatives to traditional ones. The first part assesses different fractionated architectures and compares them with traditional ones in terms of utility and cost for a given mission and given level of performance. A framework based on Multi-Attribute Tradespace Exploration was used to analyze the impact of fractionation, first at spacecraft level for a single mission, and second, at infrastructure level, when the spacecraft is part of the infrastructure. The study demonstrates that if space assets flexibility is valued enough, customers would choose fractionated spacecraft over traditional ones.The second part of the thesis examines the impact of spacecraft fractionation on the aerospace industry to understand why despite so many potential benefits, there are major barriers that prevent its implementation. Such an innovative concept could actually create a whole new paradigm in which today's protoflight approach would become a mass production approach, which would bring sweeping changes in today's space industry organization. This thesis explores policy options to increase the private sector's ability and motivation to implement fractionation and makes specific recommendations to enable the shift from today's paradigm to the fractionated spacecraft paradigm.

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“…Additionally others have tried to develop empirical measures of flexibility [Chen and Yuan, 1998], adaptability [Li et al, 2007], and robustness [Hwang and Park, 2005] in order to assist in this endeavor. Recent work has tried to synthesize these definitions into a prescriptive six-element framework in the space system domain [Nilchiani, 2005;Nilchiani and Hastings, 2007].…”

Section: Introductionmentioning

confidence: 99%

Defining changeability: Reconciling flexibility, adaptability, scalability, modifiability, and robustness for maintaining system lifecycle value

Ross

Rhodes

Hastings

2008

Systems Engineering

Self Cite

309

217

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Designing and maintaining systems in a dynamic contemporary environment requires a rethinking of how systems provide value to stakeholders over time. Developing either changeable or classically robust systems are approaches to promoting value sustainment. But, ambiguity in definitions across system domains has resulted in an inability to specify, design, and verify to ilities that promote value sustainment. In order to develop domain-neutral constructs for improved system design, the definitions of flexibility, adaptability, scalability, modifiability, and robustness are shown to relate to the core concept of "changeability," described by three aspects: change agents, change effects, and change mechanisms. In terms of system form or function parameter changes, flexibility and adaptability reflect the location of the change agent-system boundary external or internal respectively. Scalability, modifiability, and robustness relate to change effects, which are quantified differences in system parameters before and after a change has occurred. The extent of changeability is determined using a tradespace network formulation, counting the number of possible and decision maker acceptable change mechanisms available to a system, quantified as the filtered outdegree. Designing changeable systems allows for the possibility of maintaining value delivery over a system lifecycle, in spite of changes in contexts, thereby achieving value robustness.

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Measuring the Value of Flexibility in Space Systems: A Six‐Element Framework

Cited by 79 publications

References 12 publications

Case Studies of Historical Epoch Shifts: Impacts on Space Systems and their Responses

Case Studies of Historical Epoch Shifts: Impacts on Space Systems and their Responses

Assessing the Fractionated Spacecraft Concept

Defining changeability: Reconciling flexibility, adaptability, scalability, modifiability, and robustness for maintaining system lifecycle value

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