A method of estimating the costs of future space transportation systems (STSs) involves classical activity-based cost (ABC) modeling combined with systematic utilization of the knowledge and opinions of experts to extend the process-flow knowledge of existing systems to systems that involve new materials and/or new architectures. The expert knowledge is particularly helpful in filling gaps that arise in computational models of processes because of inconsistencies in historical cost data. Heretofore, the costs of planned STSs have been estimated following a "top-down" approach that tends to force the architectures of new systems to incorporate process flows like those of the space shuttles. In this ABC-based method, one makes assumptions about the processes, but otherwise follows a "bottoms up" approach that does not force the new system architecture to incorporate a space-shuttle-like process flow. Prototype software has been developed to implement this method. Through further development of software, it should be possible to extend the method beyond the space program to almost any setting in which there is a need to estimate the costs of a new system and to extend the applicable knowledge base in order to make the estimate.

This work was done by David B. Fortner of Command and Control Technologies, Inc., and Alex J. Ruiz-Torres of the University of Texas at El Paso for Kennedy Space Center. For further information, contact:

Kevin Brown

Command and Control Technologies

1425 Chaffee Drive, Suite 1

Titusville, FL 32780

(321) 264-1193

E-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.

Refer to KSC-12512.

NASA Tech Briefs Magazine

This article first appeared in the March, 2004 issue of NASA Tech Briefs Magazine.

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