A STATISTICAL APPROACH TO PAYLOAD OPERATIONS FEASIBILITY ASSESSMENTS FOR 
TACTICAL PLANNING

Donald Larson, Jeff Hagopian
donald.larson@msfc.nasa.gov
NASA/MSFC

Abstract
International Space Station (ISS) program planning is characterized by three 
chronological phases: 1) the strategic phase, 2) the tactical phase, and 3) the 
execution phase. The level of detail and type of planning that is performed 
varies for each of these planning phases. The planning results of one phase 
feed the planning functions of the next phase; i.e., tactical planning results 
feed the execution planning phase. Within the tactical planning phase, one of 
the key planning functions is to perform an operations feasibility assessment. 
This assessment addresses the entire station complement, including system and 
payload operations. The operations feasibility assessment is intended to insure 
that operations are compatible across the station, and that station resources 
are being allocated in an efficient manner. Due to the different characteristics 
of system and payload operations, the operations feasibility assessment is 
subdivided into a systems assessment and a payload assessment. The systems 
assessment is oriented around the generation of a single schedule for analysis, 
while the payload assessment approach is based on the generation of a large number 
of schedules with a statistical analysis of the results. This paper focuses 
on the payload operations feasibility assessment. Provided in this paper are: 
an overview of the operations feasibility assessment (both systems and payloads), 
a discussion of why different approaches are being implemented for systems and 
payloads, a detailed description of the payload assessment process, the results 
of a sample datacase, and a summary of the advantages and disadvantages of the 
statistical approach to the payload operations feasibility assessment.