A Survey of Cost Estimating Methodologies for Distributed Spacecraft Missions

Satellite constellations and Distributed Spacecraft Mission (DSM) architectures offer unique benefits to Earth observation scientists and unique challenges to cost estimators. The Cost and Risk (CR) module of the Tradespace Analysis Tool for Constellations (TAT-C) being developed by NASA Goddard seeks to address some of these challenges by providing a new approach to cost modeling, which aggregates existing Cost Estimating Relationships (CER) from respected sources, cost estimating best practices, and data from existing and proposed satellite designs. Cost estimation through this tool is approached from two perspectives: parametric cost estimating relationships and analogous cost estimation techniques. The dual approach utilized within the TAT-C CR module is intended to address prevailing concerns regarding early design stage cost estimates, and offer increased transparency and fidelity by offering two preliminary perspectives on mission cost. This work outlines the existing cost model, details assumptions built into the model, and explains what measures have been taken to address the particular challenges of constellation cost estimating. The risk estimation portion of the TAT-C CR module is still in development and will be presented in future work. The cost estimate produced by the CR module is not intended to be an exact mission valuation, but rather a comparative tool to assist in the exploration of the constellation design tradespace. Previous work has noted that estimating the cost of satellite constellations is difficult given that no comprehensive model for constellation cost estimation has yet been developed, and as such, quantitative assessment of multiple spacecraft missions has many remaining areas of uncertainty. By incorporating well-established CERs with preliminary approaches to approaching these uncertainties, the CR module offers more complete approach to constellation costing than has previously been available to mission architects or Earth scientists seeking to leverage the capabilities of multiple spacecraft working in support of a common goal

Managing the impact of change through survivability and pliability to achieve viable systems of systems

Thesis (Ph. D.)--Massachusetts Institute of Technology, Engineering Systems Division, 2013.Cataloged from PDF version of thesis.Includes bibliographical references (p. 195-202).As technology improves, traditional systems are being interconnected into larger systems of systems (SoS) that operate in diverse contexts, where numerous perturbations exist that threaten the ability of the SoS to deliver acceptable value to its diverse set of stakeholders. Furthermore, the systems of systems themselves can change form voluntarily or involuntarily in response to contextual variability or stakeholder whims. Various system properties, or "-ilities" have been defined that may help traditional systems provide value to stakeholders in spite of change, but they have not specifically addressed the issue of systems operating within larger systems of systems. This dissertation defines the concept of viability for engineered systems, as a likelihood that systems will satisfy their stakeholder needs over the system's expected lifetime, and identifies and develops strategies that system architects can use to create viable systems. The concept of viability helps system architects design systems that can survive contextual perturbations, whether they are from entities outside the traditional system boundary, or from other constituent systems within a SoS. In addition to external perturbations, this dissertation addresses the need to ensure that endogenous changes made to improve value delivery, do not inadvertently cause unintended interactions that harm the system overall. This is particularly a concern with the proliferation of systems of systems, and the recent drive towards making systems more changeable as a mechanism for value sustainment in dynamic environments. A new "ility", pliability, is introduced that specifies the limits on how a system can change, without "breaking" or violating an architecture that was intended and validated. Like changeability, pliability increases robustness by allowing systems to voluntarily change in response to dynamic contexts, and increases survivability and robustness by increasing the likelihood that unintentional changes are still within the set of allowable instances. It also distinguishes allowable changes from those that would require validation, reducing the effort required to get those changes approved by a diverse set of stakeholders.by Brian Mekdeci.Ph.D

Clinical Sequencing Exploratory Research Consortium: Accelerating Evidence-Based Practice of Genomic Medicine

Despite rapid technical progress and demonstrable effectiveness for some types of diagnosis and therapy, much remains to be learned about clinical genome and exome sequencing (CGES) and its role within the practice of medicine. The Clinical Sequencing Exploratory Research (CSER) consortium includes 18 extramural research projects, one National Human Genome Research Institute (NHGRI) intramural project, and a coordinating center funded by the NHGRI and National Cancer Institute. The consortium is exploring analytic and clinical validity and utility, as well as the ethical, legal, and social implications of sequencing via multidisciplinary approaches; it has thus far recruited 5,577 participants across a spectrum of symptomatic and healthy children and adults by utilizing both germline and cancer sequencing. The CSER consortium is analyzing data and creating publically available procedures and tools related to participant preferences and consent, variant classification, disclosure and management of primary and secondary findings, health outcomes, and integration with electronic health records. Future research directions will refine measures of clinical utility of CGES in both germline and somatic testing, evaluate the use of CGES for screening in healthy individuals, explore the penetrance of pathogenic variants through extensive phenotyping, reduce discordances in public databases of genes and variants, examine social and ethnic disparities in the provision of genomics services, explore regulatory issues, and estimate the value and downstream costs of sequencing. The CSER consortium has established a shared community of research sites by using diverse approaches to pursue the evidence-based development of best practices in genomic medicine