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Shishko, Robert

Publications and source records attributed to Shishko, Robert.

30 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS2006

The Application of Architecture Frameworks to Modelling Exploration Operations Costs

Developments in architectural frameworks and system-of-systems thinking have provided useful constructs for systems engineering. DoDAF concepts, language, and formalisms, in particular, provide a natural way of conceptualizing an operations cost model applicable to NASA's space exploration vision. Not all DoDAF products have meaning or apply to a DoDAF inspired operations cost model, but this paper describes how such DoDAF concepts as nodes, systems, and operational activities relate to the development of a model to estimate exploration operations costs. The paper discusses the specific implementation to the Mission Operations Directorate (MOD) operational functions/activities currently being developed and presents an overview of how this powerful representation can apply to robotic space missions as well.

Department of Defense Architecture Framework (DoDA↗
NASA NTRS2004

Developing Analogy Cost Estimates for Space Missions

The analogy approach in cost estimation combines actual cost data from similar existing systems, activities, or items with adjustments for a new project's technical, physical or programmatic differences to derive a cost estimate for the new system. This method is normally used early in a project cycle when there is insufficient design/cost data to use as a basis for (or insufficient time to perform) a detailed engineering cost estimate. The major limitation of this method is that it relies on the judgment and experience of the analyst/estimator. The analyst must ensure that the best analogy or analogies have been selected, and that appropriate adjustments have been made. While analogy costing is common, there is a dearth of advice in the literature on the 'adjustment methodology', especially for hardware projects. This paper discusses some potential approaches that can improve rigor and repeatability in the analogy costing process.

space mission cost↗
NASA NTRS2004

MESSOC

Explore the source record for details and available documents.

space station↗
NASA NTRS2001

Risk analysis simulation of rover operations for Mars surface exploration

Risk management advocates have long sought to directly influence the early stages of the systems engineering process through a more effective role in system design trade studies. The principal obstacle to this has been the lack of credible ways to represent and quantify mission risk—that is, a combination of the probability of mission success (“system safety”) and science value—for the project manager and the rest of the design team. If it were possible to quantify mission risk, then the effects of proposed mission and system design changes could be calculated, and along with life-cycle costs, could be used to explore the design space more extensively and select better designs. JPL has been working to build the capability to quantify the probability of mission success using a federation of diverse simulations and models, each of which contributes some vital piece of the puzzle. The initial institutional focus has been on Mars surface operations. This ensemble computing framework enables the diverse models and simulations to work together seamlessly. Recent work at JPL has demonstrated the capability to exercise this ensemble from end-to-end using an Oracle-based database to automatically move results from one model/simulation to the next stage in the analysis.

Shishko, Robert↗
NASA NTRS2000

Summary of Results from the Risk Management Program for the Mars Microrover Flight Experiment

On 4 July 1997, the Mars Pathfinder landed on the surface of Mars carrying the first planetary rover, known as the Sojourner. Formally known as the Microrover Flight Experiment (MFEX), the Sojourner was a low cost, high-risk technology demonstration, in which new risk management techniques were tried. This paper summarizes the activities and results of the effort to conduct a low-cost, yet meaningful risk management program for the MFEX. The specific activities focused on cost, performance, schedule, and operations risks. Just as the systems engineering process was iterative and produced successive refinements of requirements, designs, etc., so was the risk management process. Qualitative risk assessments were performed first to gain some insights for refining the microrover design and operations concept. These then evolved into more quantitative analyses. Risk management lessons from the manager's perspective is presented for other low-cost, high-risk space missions.

Shishko, Robert↗
NASA NTRS1997

Risk Analysis and System Trades inthe Mars Sample Return (MSR) Mission

Risk Managenent advocates have long sought to directly influence the early stages of the systems engineering process through a more effective role in system design trade studies. The principal obstacle to this has been the lack of credible ways to represent and quantify mission risk that is, missios return form a probablistic viewpoint-for the project manager and the rest of the design team.

Risk Analysis Mars Sample Return↗
NASA NTRS1995

NASA Systems Engineering Handbook

This handbook brings the fundamental concepts and techniques of systems engineering to NASA personnel in a way that recognizes the nature of NASA systems and environment. It is intended to accompany formal NASA training courses on systems engineering and project management when appropriate, and is designed to be a top-level overview. The concepts were drawn from NASA field center handbooks, NMI's/NHB's, the work of the NASA-wide Systems Engineering Working Group and the Systems Engineering Process Improvement Task team, several non-NASA textbooks and guides, and material from independent systems engineering courses taught to NASA personnel. Five core chapters cover systems engineering fundamentals, the NASA Project Cycle, management issues in systems engineering, systems analysis and modeling, and specialty engineering integration. It is not intended as a directive. Superseded by: NASA/SP-2007-6105 Rev 1 (20080008301).

Shishko, Robert↗
NASA NTRS1993

Management issues in systems engineering

When applied to a system, the doctrine of successive refinement is a divide-and-conquer strategy. Complex systems are sucessively divided into pieces that are less complex, until they are simple enough to be conquered. This decomposition results in several structures for describing the product system and the producing system. These structures play important roles in systems engineering and project management. Many of the remaining sections in this chapter are devoted to describing some of these key structures. Structures that describe the product system include, but are not limited to, the requirements tree, system architecture and certain symbolic information such as system drawings, schematics, and data bases. The structures that describe the producing system include the project's work breakdown, schedules, cost accounts and organization.

Shishko, Robert↗
NASA NTRS1992

NASA systems engineering handbook. Draft

This handbook is intended to provide information on systems engineering that will be useful to NASA system engineers, especially new ones. Its primary objective is to provide a generic description of systems engineering as it should be applied throughout NASA. Field Center Handbooks are encouraged to provide center-specific details of implementation. For NASA system engineers to choose to keep a copy of this handbook at their elbows, it must provide answers that cannot be easily found elsewhere. Consequently, it provides NASA-relevant perspectives and NASA-particular data. NASA management instructions (NMI's) are referenced when applicable. This handbook's secondary objective is to serve as a useful companion to all of the various courses in systems engineering that are being offered under NASA's auspices. The coverage of systems engineering is general to techniques, concepts, and generic descriptions of processes, tools, and techniques. It provides good systems engineering practices, and pitfalls to avoid. This handbook describes systems engineering as it should be applied to the development of major NASA product and producing systems.

Shishko, Robert↗
NASA NTRS1990

Design-Tradeoff Model For Space Station

System Design Tradeoff Model (SDTM) computer program produces information which helps to enforce consistency of design objectives throughout system. Mathematical model of set of possible designs for Space Station Freedom. Program finds particular design enabling station to provide specified amounts of resources to users at lowest total (or life-cycle) cost. Compares alternative design concepts by changing set of possible designs, while holding specified services to users constant, and then comparing costs. Finally, both costs and services varied simultaneously when comparing different designs. Written in Turbo C 2.0.

Chamberlain, Robert G.↗
NASA NTRS1990

MESSOC capabilities and results

MESSOC (Model for Estimating Space Station Operations Costs) is the result of a multi-year effort by NASA to understand and model the mature operations cost of Space Station Freedom. This paper focuses on MESSOC's ability to contribute to life-cycle cost analyses through its logistics equations and databases. Together, these afford MESSOC the capability to project not only annual logistics costs for a variety of Space Station scenarios, but critical non-cost logistics results such as annual Station maintenance crewhours, upweight/downweight, and on-orbit sparing availability as well. MESSOC results using current logistics databases and baseline scenario have already shown important implications for on-orbit maintenance approaches, space transportation systems, and international operations cost sharing.

Shishko, Robert↗