Space Environment Requirements Engineering (The Design of Reliable Spacecraft)

DURATION: TWO DAYS
COURSE NO.: 2085

With spacecraft systems steadily growing more complex and with commercial, off-the-shelf components seeing increasing utilization in space, it is not surprising that the environment and its effects have become major concerns for the spacecraft designer. This course addresses these concerns and provides the spacecraft builder with the tools necessary to limit the effects of the space environment. As the old adage "An ounce of prevention is worth a pound of cure" is very apt for spacecraft environment effects, this course will emphasize methods of identifying environmental issues early in a program when design changes are relatively inexpensive. It will also address the often costly and confusing process of identifying the possible environmental sources of system anomalies. The course will concentrate primarily on the natural environments associated with the Sun, neutral atmospheres, the space plasma environment, trapped radiation, cosmic rays, solar proton events, meteoroids, and space debris. The interactions to be covered will include oxygen erosion, glow, spacecraft charging, single event effects, buried charge, and hypervelocity meteoroid impacts. The latest techniques for identifying and mitigating these effects will be covered. On the practical side, appropriate guidelines and requirements will be presented to assist the spacecraft engineer in developing a coherent approach to mitigation. The course will help you to develop reliable, more survivable spacecraft and to be able to identify the effects of the space environment on their systems.

COURSE MATERIALS:
Include the text "Spacecraft Environment Interactions" by D. Hastings and H. Garrett, plus extensive notes and reference materials.

Spacecraft designers interested in designing reliable, survivable spacecraft and mission planners hoping to limit the effects of the space environment on spacecraft.

Basic concepts and definitions of the space environment. The types and characteristics of the major spacecraft interactions. Methods of identifying anomalies associated with the space environment. Key guidelines and standards for addressing environmental design issues. Tools (software, etc.) for evaluating the effects of the environment on a specific design or mitigation technique. The information necessary to convince upper level managers of the importance of an environmental protection program. Methods for preventing or mitigating the worst effects of the space environment.

1. Introduction.
   

   The Introduction will answer the question: Why do we care about the space environment and its effects? It will provide examples of actual environmental effects on spacecraft. The course will be outlined with emphasis on what the student will learn and how that knowledge can be applied to actual situations.

2. Basic Concepts.
   

   This section will define basic concepts such as Energy, Flux, and Fluence. The ideas of a LET and a Heinrich Curve will be introduced--these will be later used to estimate the effects of high energy particles on microelectronics. The concept of a Distribution Function will be described and its use in defining such useful quantities as the number density and number flux will be demonstrated. The characteristic Scale Lengths for the different environments and interactions will be approximated--these values are useful in determining when an effect might be important. The section will conclude with a discussion of basic Plasma Motions and the Adiabatic Invariants--quantities necessary in modeling radiation environments.

3. Environment.
   

   Starting with the Solar Environment and its influence on Space Weather, this section will systematically review the principle natural environments responsible for spacecraft interactions. Planetary Atmospheres and the Space Plasma Environment will be covered. The Radiation Environment, including trapped radiation, cosmic rays, and solar proton events and the Macroscopic Particle Environment (e.g., space debris and micrometeoroids) will be described in detail.

4. Interactions.
   

   Neutral Gas Interactions such as oxygen erosion and spacecraft glow will be described in this section and their effects on spacecraft evaluated. Plasma Interactions, including spacecraft charging, plasma wakes, and VxB effects will be reviewed. Space Radiation Effects such as Single Event Upsets, Total Ionizing Dose, and Buried Charge will be considered and examples of their effects on systems presented. Particulate Interactions as the result of hypervelocity impacts on spacecraft surfaces will be the final area of concern.

5. Applications.
   

   Examples of actual mission results and of environments and interactions for typical missions in Earth orbit will be described. In addition, representative missions in the inner solar system (where solar arrays can be used) and the outer solar system (where RTGs are necessary) will be presented to illustrate the potential differences between these types of spacecraft.

6. The Future.
   

   This concluding section will start by summarizing where we are. It will offer suggestions as to where we are going and what we will need to know. It will conclude with a review of where an engineer or designer can go to find help.