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Advanced Life Support System Value MetricThe NASA Advanced Life Support (ALS) Program is required to provide a performance metric to measure its progress in system development. Extensive discussions within the ALS program have reached a consensus. The Equivalent System Mass (ESM) metric has been traditionally used and provides a good summary of the weight, size, and power cost factors of space life support equipment. But ESM assumes that all the systems being traded off exactly meet a fixed performance requirement, so that the value and benefit (readiness, performance, safety, etc.) of all the different systems designs are exactly equal. This is too simplistic. Actual system design concepts are selected using many cost and benefit factors and the system specification is then set accordingly. The ALS program needs a multi-parameter metric including both the ESM and a System Value Metric (SVM). The SVM would include safety, maintainability, reliability, performance, use of cross cutting technology, and commercialization potential. Another major factor in system selection is technology readiness level (TRL), a familiar metric in ALS. The overall ALS system metric that is suggested is a benefit/cost ratio, [SVM + TRL]/ESM, with appropriate weighting and scaling. The total value is the sum of SVM and TRL. Cost is represented by ESM. The paper provides a detailed description and example application of the suggested System Value Metric.
Document ID
Acquisition Source
Ames Research Center
Document Type
Jones, Harry W.
(NASA Ames Research Center Moffett Field, CA United States)
Arnold, James O.
Date Acquired
August 20, 2013
Publication Date
January 1, 1999
Subject Category
Man/System Technology And Life Support
Meeting Information
Meeting: International Conference for Life Support Science
Location: Houston, TX
Country: United States
Start Date: January 1, 1999
Funding Number(s)
PROJECT: RTOP 199-61-01
Distribution Limits
Work of the US Gov. Public Use Permitted.

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