Best Practices for Generating Space Environment Specifications with Modern Tools

• T. B. Guild, S. C. Davis, A. J. Boyd, T. P. O'Brien, J. F. Fennell, J. E. Mazur, D. G. Brinkman, G. E. Peterson, and A. B. Jenkin, Best Practices for Generating Space Environment Specifications with Modern Tools, Aerospace Report TOR-2022-00016, Chantilly, VA (31 Dec 2021).

Abstract

At the beginning of a satellite acquisition, the organization responsible for satellite design must estimate the space environment the satellite will experience throughout its mission lifetime, usually captured in a document referred to as the program environmental specification. The goal of an environment specification is to completely specify the severity of the space environment the mission must operate in, subject to the appropriate conservatism commensurate with the risk tolerance of the mission, for the extent of the mission lifetime. Many tools exist that can assist in the generation of a complete, appropriate environment specification, but these tools are continually developed on faster timescales than satellites are designed and built.

The purpose of this document is to describe the current generation of tools and methods and provide several worked examples to produce a preliminary space environmental specification for the acquisition of a satellite system. This document is intended to be used as an introduction to the subject by survivability engineers new to space vehicle engineering, or an introduction to the latest tools for longtime experts who are unfamiliar with these new capabilities. Sections contained herein are devoted to describing tools, including AE9/AP9-IRENE, the CREME tools, solar energetic particle models, low-energy plasma definitions, micrometeoroids, orbital debris, and the atomic oxygen environment of the upper atmosphere.

These tools are then used to provide worked examples of appropriate environment specifications for whole-mission-accumulated quantities and for whole-mission worst-case quantities. Mission-accumulated environments include trapped electron fluences, proton fluences (trapped and solar), galactic cosmic rays, atomic oxygen ram fluence, micrometeoroid and orbital debris environments and mitigation, and low-energy plasma fluence for surface degradation. Worst-case quantities computed include worst-case electron flux for internal charging mitigation, worst-case proton flux and linear energy transfer flux for single-event effects design, and worst-case low-energy electron fluxes for surface charging design. We also discuss specification-related topics such as model updates, uniform documentation, and radiation design margin, and finally look toward future model and tool development.

We hope this document will serve the satellite engineering community as a useful starting point for the generation of complete and appropriate environment specifications.