MCF > Detailed Design and Analysis > Electrical >

Radiation Analysis

Scope and Description

This topic page covers radiation analysis of spacecraft electronics. This includes modeling and of the radiation environment based on the spacecraft orbit and shielding of electronic components. Modeling and analysis of radiation effects typically starts with component-level effects, followed by analysis of how these effects will extend to the rest of the electronic system. Commercial off-the-shelf electronic components are commonplace in smallsats and provide significant cost, schedule, and performance advantages over traditional, radiation hardened alternatives; however, their radiation susceptibilities can create unacceptable risk of failure without proper analysis of (1) the environment to inform shielding and part selection and (2) single event effects (SEEs) and total ionizing dose (TID) effects on components to inform and verify architectural, circuit, and software design for reliability.

Resources under this topic area are primarily software tools for radiation analysis. Fortunately, many of these are available for free online.

Best Practices and Lessons Learned

  • Use conservative parameters in early-stage radiation environment modeling (e.g., in selection of solar max/min options or confidence levels), but don't overdo it. Conduct a sensitivity analysis to inform the appropriate level of conservatism. Include team members in this process who are familiar with the cost and performance impacts of shielding, part selection, and circuit design for elevated radiation requirements and aim to strike a balance between reliability and cost.
  • The increased accuracy of high-accuracy radiation environment modeling with full particle transport models (e.g., Geant4) is not usually not worth the effort and required expertise for smallsat missions.
  • When procuring smallsat subsystems, work with the vendor to understand the worst-case behavior of the subsystem due to SEEs that are above the "operate thorough" energy but below the "survival" rating. Use this information to ensure that the survival behavior cannot cause downstream faults or destructive effects.

Resources

Software Tool
NASA

This interactive online software tool offers a step-by-step guide for determining radiation risks that ... apply given a set of simple input from the user. Smallsat teams can develop dose depth curves and single event effects (SEE) plots based on the orbit and other input parameters. In addition, R-GENTIC provides advice on electronics and software/firmware design for radiation tolerance in the specified environment.

White Paper
NASA

This page in the NASA Public Lessons Learned System describes the importance of establishing a "mandatory ... closed-loop system for detailed, independent, and timely technical reviews of all analyses performed in support of the reliability/design process." These reviews are important for detecting design defects.

Software Tool
Vanderbilt University

SEAM is a web application for modeling assurance cases integrated with system models. SEAM supports the ... Goal Structuring Notation (GSN) standard and a subset of the SysML system modeling standard. Documentation and video tutorials are provided.

Article
Doug Sinclair et al.

This white paper provides a "Careful COTS" approach to component selection and testing as they both relate ... to radiation effects and smallsat missions. The presented approach is particularly applicable to LEO missions that leverage COTS components.

Software Tool
Vanderbilt University

This web-based software tool is a widely-used and NASA-supported SEE rate prediction utility. The tool ... takes inputs related to a spacecrafts anticipated orbit and shielding, simulates the corresponding radiation environment after such shielding, and then computes a device's SEE rates given its SEE cross-sections.

Software Tool
EMPC

This software tool provides systems engineers with an easy-to-use graphical user interface for creating ... 3D models of complex objects to then perform radiation effects analysis. This proven tool used by organizations such as NASA, CalTech JPL, and JHU APL, calculates radiation effects, weight-optimized shielding, total dose, and damage parameters.

Software Tool
TRAD

A 3D CAD tool used for advanced radiation dose analysis and shielding optimization of electronic components ... on spacecraft. The software tool is composed of multiple modules such as the radiation CAD interface, ray tracing calculation, and the scripting module. This subscription-based tool can be purchased on an annual basis and provides a wide range of radiation analysis capabilities.

Software Tool
TRAD

This free software tool computes the space environment and the radiation effects imposed on electronic ... hardware and electronic assemblies. A variety of radiation effects on spacecraft can be assessed using Omere such as; dose depth, displacement dose equivalent fluence (DDEF), SEE rate, and solar cell degradation.

Get Involved