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Proceedings Paper

High-level simulation of JWST event-driven operations
Author(s): R. Henry; W. Kinzel
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Paper Abstract

The James Webb Space Telescope (JWST) has an event-driven architecture: an onboard Observation Plan Executive (OPE) executes an Observation Plan (OP) consisting of a sequence of observing units (visits). During normal operations, ground action to update the OP is only expected to be necessary about once a week. This architecture is designed to tolerate uncertainty in visit duration, and occasional visit failures due to inability to acquire guide stars, without creating gaps in the observing timeline. The operations concept is complicated by the need for occasional scheduling of timecritical science and engineering visits that cannot tolerate much slippage without inducing gaps, and also by onboard momentum management. A prototype Python tool called the JWST Observation Plan Execution Simulator (JOPES) has recently been developed to simulate OP execution at a high level and analyze the response of the Observatory and OPE to both nominal and contingency scenarios. Incorporating both deterministic and stochastic behavior, JOPES has potential to be a powerful tool for several purposes: requirements analysis, system verification, systems engineering studies, and test data generation. It has already been successfully applied to a study of overhead estimation bias: whether to use conservative or average-case estimates for timing components that are inherently uncertain, such as those involving guide-star acquisition. JOPES is being enhanced to support interfaces to the operational Proposal Planning Subsystem (PPS) now being developed, with the objective of "closing the loop" between testing and simulation by feeding simulated event logs back into the PPS.

Paper Details

Date Published: 13 September 2012
PDF: 12 pages
Proc. SPIE 8448, Observatory Operations: Strategies, Processes, and Systems IV, 84480S (13 September 2012); doi: 10.1117/12.924923
Show Author Affiliations
R. Henry, Space Telescope Science Institute (United States)
W. Kinzel, Space Telescope Science Institute (United States)

Published in SPIE Proceedings Vol. 8448:
Observatory Operations: Strategies, Processes, and Systems IV
Alison B. Peck; Robert L. Seaman; Fernando Comeron, Editor(s)

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