Attachment T - L1 Series Radiation Requirements Document.pdf

DOORS EXPORT Effective Date: November 3, 2023 Effective Date: November 3, 2028

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Space Weather (SW) Next L1 Series, Code 491.0 L1SERIES-SYS-REQ-0023, Revision -

Space Weather (SW) Next L1 Series

L1 Series Radiation Requirements Document (RRD)

SWO CMO

December 3, 2023

Released

U.S. Department of Commerce (DOC) National Oceanic and Atmospheric Administration (NOAA) NOAA Satellite and Information Service (NESDIS) National Aeronautics and Space Administration (NASA)

Effective Date: November 3, 2023 ii Check https://ipdtdms.gsfc.nasa.gov/frontmenu_dsp.cfm to verify that this is the correct version prior to use.

L1 Series Radiation Requirements Document (RRD) Review/Signature/Approval Page

Prepared by:

Orignally signed on 11-08-23 by:

Matthew Joplin Radiation Engineer L1 Series Project NASA Goddard Space Flight Center, code 561

Approved By:

Originally signed on 11-09-23 by:

Martin Fraeman Electrical Systems Engineer Johns Hopkins University Applied Physics Lab

Orignally signed on 11-13-23 by:

Clark (Skip) Owens Systems Engineer

NASA Goddard Space Flight Center, code 493

Originally signed on 11-13-23 by:

Brennan Nowak Deputy Project Manager

Originally signed on 12-01-23 by:

John (Tim) Van Sant Project Manager iii Check https://ipdtdms.gsfc.nasa.gov/frontmenu_dsp.cfm to verify that this is the correct version prior to use.

Preface

This document is under SWO Program configuration control. Once this document is approved, SWO approved changes are handled in accordance with Class I and Class II change control requirements as described in the SWO Configuration Management Procedure, and changes to this document shall be made by complete revision.

In this plan, all mandatory actions (i.e., requirements) are denoted by statements containing the term “shall.” The terms “may” or “can” denote discretionary privilege or permission; “should” denotes a good practice and is recommended but not required; “will” denotes expected outcome;

and “are/is” denotes descriptive material.

Any questions should be addressed to:

SWO Configuration Management Office

NASA/GSFC

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Change History Log

Revision Effective Date Description of Changes (Reference the CCR & CCB/ERB Approval Date)

Rev - November 3, This was CCR L1SERIES-CCR-0024 to baseline the document and was approved on November 3, 2023.

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Table of TBCs/TBDs/TBRs/TBSs vii Check https://ipdtdms.gsfc.nasa.gov/frontmenu_dsp.cfm to verify that this is the correct version prior to use.

Table of Contents

1 SCOPE AND INTENT

2 MISSION APPLICABLE DOCUMENTATION

3 INTERPRETING REQUIREMENTS

4 RADIATION HARDNESS ASSURANCE DOCUMENT COMPLIANCE

4.1 Orbital Considerations

4.1.1 Interplanetary Space

4.2 The Solar Cycle

4.3 Background Solar Particle Flux

4.3.1 Solar Radiation Storms

4.4 Galactic Cosmic Rays

4.5 Shielding Estimate

4.6 Total Ionizing Dose

4.6.1 Total Ionizing Dose Levels

4.7 Displacement Damage Dose

4.7.1 Displacement Damage Dose Levels

4.8 Single Event Effects

4.8.1 Impact of Single-events on the Observatory

4.8.2 Solar Cycle Performance

4.8.3 Solar Particle Event Operations

4.8.4 Solar Flare Survival

4.9 Observatory Charging

4.9.1 Charging Verification

4.9.2 ESD Suppression on External Surfaces

5 APPENDIX I: RADIATION EFFECTS DEFINITIONS

5.1 Reference Documents / Standards

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List of Figures

Figure 1 TID Dose-Depth Curves Figure 2 DDD in Si Dose-Depth Curve Figure 3 Bounding Case (5.5 years, 2033) Equivalent Fluence Silicon Materials Figure 4 DDD in GaAs Dose-Depth Curve Figure 5 Bounding Case (5.5 years, 2033) Equivalent Fluence GaAs Materials Figure 6 LET Spectrum of GCR Background Figure 7 Solar LET Spectrum Background Figure 8 Solar Proton Background Spectra Figure 9 Peak Solar Particle Event Flux Figure 10 Peak Solar Proton Flux

List of Tables

Table 1 Total Ionizing Dose vs. Shielding Thickness Table 2 Displacement Damage Dose in Silicon vs. Shielding Thickness Table 3 Bounding Case (5.5 years, 2033) Equivalent Fluence Silicon Materials Table 4 Displacement Damage Dose in Gallium Arsenide vs. Shielding Thickness Table 5 Bounding Case (5.5 years, 2033) Equivalent Fluence GaAs Materials Table 6 LET Spectrum of GCR Background Table 7 Solar Background LET Spectrum Table 8 Solar Proton Background Flux Table 9 Peak Solar Particle Event Flux Table 10 Peak Solar Proton Flux

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1 SCOPE AND INTENT

This document is Generic Class C Radiation Engineering Input and establishes radiation environment baseline and provides guidance to assess radiation effects impact on systems with Electrical, Electronic, Electromechanical, and Electro-optical (EEEE) parts. Refer to the Radiation Hardness Assurance Requirements Document (RHARD) that establishes requirements on implementation of the EEEE system in the radiation environment described in this document.

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2 MISSION APPLICABLE DOCUMENTATION

• L1SERIES-SYS-REQ-0016 Radiation Hardness Assurance Requirements Document

(RHARD) – Contains the requirements necessary for EEEE system implementation in the mission radiation environment and outlines the project plan to control radiation effects on EEEE parts and systems as well as guidance for verification.

• L1SERIES-SC-REQ-0006 Spacecraft Mission Assurance Requirements (MAR) – Establishes EEEE Parts Control Plan (PCP) and defines the specific deliverable items to meet mission assurance requirements for payloads of a given risk classification.

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3 INTERPRETING REQUIREMENTS

The radiation environment is dynamic, and its impact depends on the criticality of the application, availability requirements of the mission, and accuracy of the conservative assumed shielding estimates. This document assumes nothing about the implementation of the EEEE system in context with the radiation environment but provides enough environmental modeling information and guidance to enable implementation of a radiation hardness assurance program.

The responsibility of the project radiation engineer is to understand the extreme radiation environment dynamics, identify hazards to EEEE systems and components, and act in accordance with the risk posture of the project to address these hazards satisfactorily to meet mission requirements.

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4 RADIATION HARDNESS ASSURANCE DOCUMENT

COMPLIANCE

The L1 Series mission observatory EEEE system is subject to degradation and anomalous behavior induced by the radiation environment described herein. The EEEE system will be implemented in accordance with the radiation hardness assurance plan to meet Total Ionizing Dose (TID), Displacement Damage Dose (DDD), and both destructive and non-destructive single event effects (SEE) requirements described in the RHARD (L1SERIES-SYS-REQ-0016).

The radiation environment consists of galactic cosmic ray ions; protons and electrons trapped in the Van Allen belts; protons and heavier ions from solar events; and solar wind plasma consisting of low energy electrons, protons, and heavier ions. The RHARD specification is an L1 Series Level 3 document and it’s compliance will be levied on the spacecraft via the Spacecraft Requirements Document (SRD) and on the instruments via the individual instrument specifications.

4.1 Orbital Considerations

The dynamics of the radiation environment are dependent on the location of the mission, whether that is within Earth’s magnetosphere, in the South Atlantic Anomaly, the Van Allen Belts, in interplanetary space, or in Jovian orbit around a gas planet. The radiation environments for each of these examples are not equivalent in the hazards they present to EEEE components and the challenges to implementing a space system.

4.1.1 Interplanetary Space

Interplanetary Space encompasses the space outside of Earth’s Magnetosphere, but not close enough to another planet to be impacted by its influence. Hence, the major contributors to the radiation environment include solar particles and galactic cosmic rays. Missions in this environment are subject to the full brunt of solar radiation, where the flux of the solar radiation is inversely proportional to the distance from the Sun.

4.2 The Solar Cycle

The activity of the sun ebbs and flows in an approximately 11-year cycle defined by the fluctuation of solar activity such as sunspots, solar flares from maximum to minimum activity.

Solar cycle 24, the last complete solar cycle at the time of writing, lasted between January 2008 and December 2019, demarcating solar minimum and the beginning of a new cycle. Solar cycle 25 is expected to last between 2019 and 2040, with solar maximum expected between 2023 and 2026. The solar cycle has the effect of modulating the galactic cosmic ray flux by way of increased galactic cosmic rays at times of minimum activity and decreased galactic cosmic rays at times of maximum activity. In addition, increased solar activity corresponds to an increased likelihood of observing solar flares that can develop into solar particle events, such as solar radiation storms and coronal mass ejections, that are directional and have greatly enhanced flux of energetic particles.

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4.3 Background Solar Particle Flux

Solar energetic particles consist of protons, electrons, and heavy ions originating from the Sun. It is a combination of the continuous solar wind plasma and sudden solar particle events or solar radiation storms. The solar wind particle fluxes fluctuate with the solar cycle and are partially responsible for the background radiation environment that induces TID, DDD, and SEE in EEEE parts as well as buildup of spacecraft charging effects on insulating materials on the surface of the spacecraft.

4.3.1 Solar Radiation Storms

Solar radiation storms, solar particle events, or coronal mass ejections, are random, localized, directional emissions of high energy particles from the Sun’s surface that represent enhancement of energetic particle fluxes possibly spanning multiple orders of magnitude. These events consequently induce increased rates of SEE and buildup of SEE in space systems that can overwhelm radiation effects mitigation. They are more likely to happen during solar maximum than solar minimum, but they can occur at any time.

4.4 Galactic Cosmic Rays

Galactic cosmic rays are high-energy particles originating outside of the solar system, primarily from supernovae. The galactic cosmic ray spectrum consists mostly of protons but includes heavy ions up to uranium and the highest energy particles found in Nature, though the associated fluxes of high energy, high-Z particles are very low.

The primary concern with Galactic Cosmic Rays is SEE.

4.5 Shielding Estimate

Effective use of shielding is critical to reducing dose effects and attenuating low energy (<10 MeV) particle flux from the space environment that may induce TID, DDD, or SEE degradation and damage within the EEEE parts. However, shielding has diminishing returns beyond a certain point for TID and DDD because high energy particles will transport through the material unless it is so thick as to be unrealistic for space flight. This is a trade-off between radiation protection and spacecraft mass.

Shielding cannot stop SEE, only attenuate the particles that cause SEE in especially sensitive EEEE parts. SEE will continue to happen. Beyond that, high-Z materials are capable shields against dose, but can produce secondary recoil particles that may cause SEE within spacecraft components.

For early stages of mission design and development, there often is not a constrained design to estimated effective shielding. As a result, common engineering practice is to estimate 100 mils of Aluminum chassis thickness as a simple solid sphere geometry until a more accurate estimate of effective shielding with a ray trace of a matured chassis or spacecraft model is possible. It is helpful in bounding expected TID and DDD degradation.

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4.6 Total Ionizing Dose

TID Calculations are based on a combination of the IRENE AP9/AE9 (trapped particles), ESP- PSYCHIC (solar particles), and SHIELDOSE-2 (shielding) models.

4.6.1 Total Ionizing Dose Levels

The bounding case is the 5.5-year mission starting in 2033.

RRD-31: The L1 Series observatory shall meet all performance requirements after exposure to the bounding case of 95th percentile mission total ionizing dose as specified in Table 1 and Figure 1.

Rationale: Mission environment consists of trapped proton, trapped electron, and solar proton fluences that could degrade performance prematurely.

Table 1 Total Ionizing Dose vs. Shielding Thickness

Al absorber thickness 5.5 years, 2033

(mm) (mils) (g cm-2) (krad-Si)

0.05 1.968 0.014 6.92E+02

0.1 3.937 0.027 4.14E+02

0.2 7.874 0.054 2.45E+02

0.3 11.811 0.081 1.79E+02

0.4 15.748 0.108 1.40E+02

0.5 19.685 0.135 1.15E+02

0.6 23.622 0.162 9.92E+01

0.8 31.496 0.216 7.63E+01 1 39.37 0.27 6.17E+01

1.5 59.055 0.405 4.21E+01 2 78.74 0.54 3.13E+01

2.5 98.425 0.675 2.49E+01 3 118.11 0.81 2.04E+01 4 157.48 1.08 1.47E+01 5 196.85 1.35 1.12E+01 6 236.22 1.62 9.13E+00 7 275.59 1.89 7.54E+00 8 314.96 2.16 6.36E+00 9 354.33 2.43 5.50E+00 10 393.7 2.7 4.75E+00 12 472.44 3.24 3.75E+00 14 551.18 3.78 3.01E+00 16 629.92 4.32 2.50E+00 18 708.66 4.86 2.12E+00 20 787.4 5.4 1.80E+00

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Figure 1 TID Dose-Depth Curves

4.7 Displacement Damage Dose

DDD calculations are based on a combination of the IRENE AP9/AE9 (trapped particles), ESP- PSYCHIC (solar particles), and NIEL (energy transfer to material) models.

4.7.1 Displacement Damage Dose Levels

The L1 Series satellite mission profile is computed and displayed in Figure 2 and Table 2 for Silicon Materials as well as Figure 4 and Table 4 for Gallium Arsenide Materials.

RRD-175: The L1 Series observatory shall meet all performance requirements after exposure to the 95th percentile mission displacement damage dose as specified in the bounding case Figure 2 and Table 2 (Silicon materials), Figure 4 and Table 4 (GaAs materials), or equivalent for other materials.

Rationale: Mission environment consists of trapped proton, trapped electron, and solar proton fluences that could degrade performance prematurely.

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Table 2 Displacement Damage Dose in Silicon vs. Shielding Thickness

Al absorber thickness 5.5 years, 2033

(mm) (mils) (g cm-2) (MeV/g-Si)

0.05 1.968 0.014 1.44E+10

0.1 3.937 0.027 8.46E+09

0.2 7.874 0.054 4.77E+09

0.3 11.811 0.081 3.39E+09

0.4 15.748 0.108 2.71E+09

0.5 19.685 0.135 2.22E+09

0.6 23.622 0.162 1.92E+09

0.8 31.496 0.216 1.49E+09

1 39.37 0.27 1.21E+09

1.5 59.055 0.405 8.38E+08

2 78.74 0.54 6.46E+08

2.5 98.425 0.675 5.14E+08

3 118.11 0.81 4.29E+08 4 157.48 1.08 3.12E+08 5 196.85 1.35 2.43E+08 6 236.22 1.62 2.01E+08 7 275.59 1.89 1.68E+08 8 314.96 2.16 1.41E+08 9 354.33 2.43 1.24E+08

10 393.7 2.7 1.09E+08 12 472.44 3.24 8.58E+07 14 551.18 3.78 7.07E+07 16 629.92 4.32 5.87E+07 18 708.66 4.86 5.03E+07 20 787.4 5.4 4.30E+07

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Figure 2 DDD in Si Dose-Depth Curve

Equivalent fluences for testing reference are tabulated in Table 3 and graphed in Figure 3.

Table 3 Bounding Case (5.5 years, 2033) Equivalent Fluence Silicon Materials

Al absorber thickness 5.5 years, 2033

(mm) (mils) (g/cm2) DDD

(MeV/g- Si)

1 MeV n/cm^2

1 MeV p/cm^2

10 MeV p/cm^2

50 MeV p/cm^2

63 MeV p/cm^2

0.05 1.968 0.014 1.44E+10 5.91E+12 2.14E+11 1.83E+12 3.72E+12 4.28E+12

0.1 3.937 0.027 8.46E+09 3.47E+12 1.26E+11 1.07E+12 2.18E+12 2.51E+12

0.2 7.874 0.054 4.77E+09 1.95E+12 7.09E+10 6.04E+11 1.23E+12 1.42E+12

0.3 11.811 0.081 3.39E+09 1.39E+12 5.04E+10 4.30E+11 8.76E+11 1.01E+12

0.4 15.748 0.108 2.71E+09 1.11E+12 4.03E+10 3.44E+11 7.00E+11 8.06E+11

0.5 19.685 0.135 2.22E+09 9.12E+11 3.31E+10 2.82E+11 5.74E+11 6.61E+11

0.6 23.622 0.162 1.92E+09 7.89E+11 2.86E+10 2.44E+11 4.97E+11 5.72E+11

0.8 31.496 0.216 1.49E+09 6.12E+11 2.22E+10 1.89E+11 3.85E+11 4.44E+11

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1 39.37 0.27 1.21E+09 4.96E+11 1.80E+10 1.53E+11 3.12E+11 3.60E+11

1.5 59.055 0.405 8.38E+08 3.43E+11 1.25E+10 1.06E+11 2.16E+11 2.49E+11

2 78.74 0.54 6.46E+08 2.65E+11 9.60E+09 8.19E+10 1.67E+11 1.92E+11

2.5 98.425 0.675 5.14E+08 2.11E+11 7.64E+09 6.51E+10 1.33E+11 1.53E+11

3 118.11 0.81 4.29E+08 1.76E+11 6.37E+09 5.43E+10 1.11E+11 1.27E+11 4 157.48 1.08 3.12E+08 1.28E+11 4.63E+09 3.95E+10 8.05E+10 9.27E+10 5 196.85 1.35 2.43E+08 9.96E+10 3.61E+09 3.08E+10 6.28E+10 7.23E+10 6 236.22 1.62 2.01E+08 8.24E+10 2.99E+09 2.55E+10 5.19E+10 5.98E+10 7 275.59 1.89 1.68E+08 6.90E+10 2.50E+09 2.13E+10 4.35E+10 5.01E+10 8 314.96 2.16 1.41E+08 5.80E+10 2.10E+09 1.79E+10 3.65E+10 4.21E+10 9 354.33 2.43 1.24E+08 5.08E+10 1.84E+09 1.57E+10 3.20E+10 3.69E+10

10 393.7 2.7 1.09E+08 4.47E+10 1.62E+09 1.38E+10 2.82E+10 3.24E+10 12 472.44 3.24 8.58E+07 3.52E+10 1.28E+09 1.09E+10 2.22E+10 2.55E+10 14 551.18 3.78 7.07E+07 2.90E+10 1.05E+09 8.96E+09 1.83E+10 2.10E+10 16 629.92 4.32 5.87E+07 2.40E+10 8.72E+08 7.44E+09 1.52E+10 1.74E+10 18 708.66 4.86 5.03E+07 2.06E+10 7.47E+08 6.37E+09 1.30E+10 1.49E+10 20 787.4 5.4 4.30E+07 1.76E+10 6.39E+08 5.44E+09 1.11E+10 1.28E+10

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Figure 3 Bounding Case (5.5 years, 2033) Equivalent Fluence Silicon Materials

Table 4 Displacement Damage Dose in Gallium Arsenide vs. Shielding Thickness

Al absorber thickness 5.5 years, 2033

(mm) (mils) (g cm2) (MeV/g-GaAs)

0.05 1.968 0.014 1.19E+10

0.1 3.937 0.027 7.03E+09

0.2 7.874 0.054 3.97E+09

0.3 11.811 0.081 2.83E+09

0.4 15.748 0.108 2.26E+09

0.5 19.685 0.135 1.85E+09

0.6 23.622 0.162 1.60E+09

0.8 31.496 0.216 1.24E+09

1 39.37 0.27 1.01E+09

1.5 59.055 0.405 7.03E+08

2 78.74 0.54 5.45E+08

2.5 98.425 0.675 4.37E+08

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3 118.11 0.81 3.67E+08 4 157.48 1.08 2.70E+08 5 196.85 1.35 2.13E+08 6 236.22 1.62 1.78E+08 7 275.59 1.89 1.50E+08 8 314.96 2.16 1.27E+08 9 354.33 2.43 1.13E+08

10 393.7 2.7 9.99E+07 12 472.44 3.24 7.99E+07 14 551.18 3.78 6.67E+07 16 629.92 4.32 5.62E+07 18 708.66 4.86 4.87E+07 20 787.4 5.4 4.22E+07

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Figure 4 DDD in GaAs Dose-Depth Curve

Equivalent fluences for testing reference are denoted in Table 5 and graphed in Figure 5

Table 5 Bounding Case (5.5 years, 2033) Equivalent Fluence GaAs Materials

Al absorber thickness 5.5 years, 2033

(mm) (mils) (g cm2) DDD

(MeV/g- GaAs)

1 MeV (n/cm^2)

1 MeV (p/cm^2)

10 MeV (p/cm^2)

50 MeV (p/cm^2)

63 MeV (p/cm^2)

0.05 1.968 0.014 1.19E+10 1.30E+13 2.21E+11 1.81E+12 3.18E+12 3.24E+12

0.1 3.937 0.027 7.03E+09 7.66E+12 1.30E+11 1.07E+12 1.87E+12 1.91E+12

0.2 7.874 0.054 3.97E+09 4.33E+12 7.35E+10 6.03E+11 1.06E+12 1.08E+12

0.3 11.811 0.081 2.83E+09 3.08E+12 5.23E+10 4.29E+11 7.52E+11 7.68E+11

0.4 15.748 0.108 2.26E+09 2.46E+12 4.17E+10 3.42E+11 6.01E+11 6.13E+11

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0.5 19.685 0.135 1.85E+09 2.02E+12 3.43E+10 2.81E+11 4.93E+11 5.03E+11

0.6 23.622 0.162 1.60E+09 1.75E+12 2.97E+10 2.43E+11 4.27E+11 4.36E+11

0.8 31.496 0.216 1.24E+09 1.35E+12 2.30E+10 1.89E+11 3.31E+11 3.38E+11

1 39.37 0.27 1.01E+09 1.10E+12 1.87E+10 1.53E+11 2.69E+11 2.75E+11

1.5 59.055 0.405 7.03E+08 7.66E+11 1.30E+10 1.07E+11 1.87E+11 1.91E+11

2 78.74 0.54 5.45E+08 5.94E+11 1.01E+10 8.28E+10 1.45E+11 1.48E+11

2.5 98.425 0.675 4.37E+08 4.76E+11 8.08E+09 6.63E+10 1.16E+11 1.19E+11

3 118.11 0.81 3.67E+08 3.99E+11 6.79E+09 5.56E+10 9.76E+10 9.97E+10 4 157.48 1.08 2.70E+08 2.94E+11 4.99E+09 4.09E+10 7.18E+10 7.34E+10 5 196.85 1.35 2.13E+08 2.32E+11 3.93E+09 3.23E+10 5.66E+10 5.78E+10 6 236.22 1.62 1.78E+08 1.93E+11 3.29E+09 2.69E+10 4.73E+10 4.83E+10 7 275.59 1.89 1.50E+08 1.64E+11 2.78E+09 2.28E+10 4.00E+10 4.09E+10 8 314.96 2.16 1.27E+08 1.39E+11 2.36E+09 1.93E+10 3.39E+10 3.46E+10 9 354.33 2.43 1.13E+08 1.23E+11 2.08E+09 1.71E+10 3.00E+10 3.06E+10

10 393.7 2.7 9.99E+07 1.09E+11 1.85E+09 1.52E+10 2.66E+10 2.72E+10 12 472.44 3.24 7.99E+07 8.70E+10 1.48E+09 1.21E+10 2.13E+10 2.17E+10 14 551.18 3.78 6.67E+07 7.26E+10 1.23E+09 1.01E+10 1.78E+10 1.81E+10 16 629.92 4.32 5.62E+07 6.12E+10 1.04E+09 8.52E+09 1.50E+10 1.53E+10 18 708.66 4.86 4.87E+07 5.30E+10 9.01E+08 7.39E+09 1.30E+10 1.32E+10 20 787.4 5.4 4.22E+07 4.59E+10 7.80E+08 6.40E+09 1.12E+10 1.15E+10

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Figure 5 Bounding Case (5.5 years, 2033) Equivalent Fluence GaAs Materials

4.8 Single Event Effects

SEE Environment calculations are based on a combination of the IRENE AP9/AE9 (trapped particles), ESP-PSYCHIC (solar particles), CREME96 (peak October 1989 solar particle event), and ISO-15390 (galactic cosmic rays).

4.8.1 Impact of Single-events on the Observatory

RRD-990: The L1 Series observatory shall not be permanently damaged or placed into an unrecoverable state due to any single-event phenomena.

Rationale: Charged particles in the mission environment are capable of destroying or upsetting the behavior of some EEEE parts and electronic systems.

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4.8.2 Solar Cycle Performance

RRD-993: The L1 Series observatory shall meet all performance requirements when operating in the bounding case assuming 100 mil Aluminum shielding of single-event effects background environment defined by Figure 6 and Table 6 (galactic cosmic rays), Figure 7 and Table 7 (solar particles), and Figure 8 and Table 8 (solar protons).

Rationale: Mission requires nominal operation during exposure to background environment.

Table 6 LET Spectrum of GCR Background

GCR

LET

(MeV cm^2/mg)

5.5 years, 2033 start

Flux > LET (#/cm^2/day)

0.1 1.90E+03

0.19 1.52E+03

0.25 1.24E+03

0.32 1.09E+03

0.41 9.64E+02

0.53 8.60E+02

0.6 7.66E+02

0.68 6.38E+02

0.88 5.74E+02

1 5.05E+02

1.3 4.12E+02

1.67 3.55E+02

1.9 3.05E+02

2.45 2.72E+02

3.59 2.44E+02

4.08 2.21E+02

5.99 1.93E+02

7.73 1.72E+02

8.78 1.52E+02

9.97 1.09E+02

14.62 7.08E+01

18.87 5.23E+01

21.44 3.97E+01

24.36 2.97E+01

31.44 2.26E+01

35.72 1.72E+01

40.58 1.30E+01

46.1 9.94E+00

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52.37 7.41E+00

59.49 5.68E+00

76.78 4.21E+00

87.23 3.22E+00

99.1 2.39E+00

Figure 6 LET Spectrum of GCR Background

Table 7 Solar Background LET Spectrum

Solar

LET

(MeVcm^2/mg)

5.5 years, 2033 start

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Flux > LET (#/cm^2/day)

0.1 7.23E+05

0.19 1.64E+05

0.25 7.70E+04

0.53 4.66E+03

0.6 3.66E+03

0.68 2.87E+03

0.88 1.72E+03

1 1.34E+03

1.67 3.46E+02

1.9 2.81E+02

2.45 1.87E+02

3.59 9.02E+01

4.08 6.96E+01

5.99 2.57E+01

7.73 1.13E+01

9.97 5.60E+00

18.87 6.97E-01

21.44 4.88E-01

24.36 3.13E-01

31.44 3.51E-03

35.72 1.03E-04

40.58 6.03E-05

46.1 3.45E-05

52.37 2.45E-05

59.49 1.65E-05

76.78 5.46E-06

87.23 3.23E-06

99.1 1.05E-06

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Figure 7 Solar LET Spectrum Background

Table 8 Solar Proton Background Flux

Solar Energy (MeV) 5.5 years, 2033 start

Flux > E (#/cm^2/day)

0.1 3.71E+07

0.14 3.71E+07

0.18 3.71E+07

0.25 3.71E+07

0.34 3.70E+07

0.46 3.70E+07

0.62 3.70E+07

0.84 3.70E+07

1.13 3.69E+07

1.54 3.68E+07

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2.82 3.63E+07

3.82 3.59E+07

5.18 3.50E+07

7.02 3.41E+07

9.51 3.19E+07

12.9 2.93E+07

17.5 2.58E+07

23.6 2.10E+07

32 1.48E+07

43.4 1.13E+07

58.8 7.13E+06

79.6 4.59E+06 108 2.31E+06 146 1.08E+06 198 5.70E+05 268 2.24E+05 363 6.22E+04 492 8.06E+03

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Figure 8 Solar Proton Background Spectra

4.8.3 Solar Particle Event Operations

RRD-1296: The L1 Series observatory shall meet data gap and availability performance requirements during exposure to the worst week peak fluxes listed in Figure 9 and Table 9 (solar particles) and Figure 10 and Table 10 (solar protons).

RRD-1297: The L1 Series observatory shall function after exposure to the worst 5-Min peak fluxes listed in Figure 9 and Table 9 (solar particles) and Figure 10 and Table 10 (solar protons).

Rationale: Rare solar flares are evaluated for survival. Operations may be disrupted temporarily.

Table 9 Peak Solar Particle Event Flux

LET

(MeVcm^2/mg)

Worst Week Flux > LET (#/cm^2/s)

Worst Day Flux >

LET

(#/cm^2/s)

Worst 5-Min Flux > LET (#/cm^2/s)

0.1 2.09E+02 1.09E+03 4.11E+03

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0.19 4.63E+01 2.44E+02 9.24E+02

0.25 2.13E+01 1.13E+02 4.28E+02

0.53 8.53E-01 4.82E+00 1.81E+01

0.6 6.57E-01 3.65E+00 1.37E+01

0.68 5.06E-01 2.76E+00 1.03E+01

0.88 2.90E-01 1.51E+00 5.64E+00

1 2.21E-01 1.12E+00 4.19E+00

1.67 4.84E-02 1.69E-01 6.15E-01

1.9 4.03E-02 1.40E-01 5.09E-01

2.45 2.89E-02 9.87E-02 3.59E-01

3.59 1.64E-02 5.51E-02 2.00E-01

4.08 1.35E-02 4.51E-02 1.63E-01

5.99 6.46E-03 2.16E-02 7.80E-02

7.73 3.62E-03 1.20E-02 4.32E-02

9.97 2.24E-03 7.41E-03 2.67E-02

18.87 4.69E-04 1.54E-03 5.52E-03

21.44 3.26E-04 1.07E-03 3.85E-03

24.36 2.08E-04 6.86E-04 2.47E-03

31.44 1.62E-06 5.04E-06 1.81E-05

35.72 8.63E-08 2.22E-07 7.99E-07

40.58 4.67E-08 1.11E-07 4.01E-07

46.1 2.76E-08 6.26E-08 2.26E-07

52.37 1.93E-08 4.36E-08 1.58E-07

59.49 1.26E-08 2.86E-08 1.03E-07

76.78 3.42E-09 7.49E-09 2.71E-08

87.23 2.00E-09 4.45E-09 1.61E-08

99.1 6.29E-10 1.39E-09 5.04E-09

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Figure 9 Peak Solar Particle Event Flux

Table 10 Peak Solar Proton Flux

Energy (MeV) Worst Week Flux > E (p/cm^2/s)

Worst Day Flux > E (p/cm^2/s)

Worst 5-Min Flux > E (p/cm^2/s)

0.1 1.05E+04 4.67E+04 1.73E+05

0.14 1.05E+04 4.67E+04 1.73E+05

0.18 1.05E+04 4.67E+04 1.73E+05

0.25 1.05E+04 4.67E+04 1.73E+05

0.34 1.05E+04 4.66E+04 1.73E+05

0.46 1.05E+04 4.66E+04 1.73E+05

0.62 1.04E+04 4.66E+04 1.73E+05

0.84 1.04E+04 4.65E+04 1.72E+05

1.13 1.04E+04 4.64E+04 1.72E+05

1.54 1.04E+04 4.62E+04 1.71E+05

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2.82 1.02E+04 4.54E+04 1.68E+05

3.82 1.01E+04 4.49E+04 1.66E+05

5.18 9.84E+03 4.35E+04 1.61E+05

7.02 9.57E+03 4.21E+04 1.56E+05

9.51 8.91E+03 3.87E+04 1.43E+05

12.9 8.12E+03 3.48E+04 1.28E+05

17.5 7.07E+03 2.97E+04 1.09E+05

23.6 5.68E+03 2.30E+04 8.42E+04

32 3.91E+03 1.49E+04 5.43E+04

43.4 2.96E+03 1.08E+04 3.92E+04

58.8 1.83E+03 6.18E+03 2.24E+04

79.6 1.17E+03 3.69E+03 1.34E+04 108 5.87E+02 1.67E+03 6.09E+03 146 2.76E+02 7.07E+02 2.62E+03 198 1.49E+02 3.55E+02 1.34E+03 268 5.91E+01 1.30E+02 5.07E+02 363 1.70E+01 3.51E+01 1.43E+02 492 2.22E+00 4.43E+00 1.86E+01

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Figure 10 Peak Solar Proton Flux

4.8.4 Solar Flare Survival

RRD-1658: The L1 Series observatory shall remain functional after exposure to the worst day peak proton flux from 3 S4 or S5 class solar radiation storms of 4 days (i.e., 12 solar storm days) during the orbit lifetime and meet SC safe state requirements.

Rationale: Solar radiation storms occur at an expected rate and elevate the proton flux, which primarily impacts the worst case SEE response of the spacecraft and functionality of susceptible EEEE parts.

4.9 Observatory Charging

4.9.1 Charging Verification

RRD-1662: Charging verification shall be conducted in accordance with NASA-HDBK-4002A w/CHANGE 1, as tailored by this document.

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Rationale: Determine if spacecraft charging is an issue for the L1 Series Observatory. If it is, then establishing a mitigation plan is necessary for mission success.

4.9.2 ESD Suppression on External Surfaces

RRD-1665: The L1 Series observatory external surfaces, if required, shall have special coatings for electrostatic discharge (ESD) suppression in the plasma environment (except where such coatings degrade performance).

Rationale: ESD because of spacecraft charging induces degradation and damage to insulating materials, and therefore suppression is necessary to protect the integrity of the spacecraft insulating materials.

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5 APPENDIX I: RADIATION EFFECTS DEFINITIONS

Displacement Damage Dose (DDD) – the mean energy deposited in a device region by radiation that goes into atomic displacements divided by the mass of the region. One common unit is MeV/g.

Electro-static Discharge (ESD) – sudden discharge of high intensity electric field that potentially degrades or damages insulating materials.

Linear Energy Transfer (LET) - a measure of the ionizing energy deposited per unit length as an energetic particle travels through a material. The common LET unit is MeV∙cm2/mg of material.

Non-Ionizing Energy Loss (NIEL) - a measure of the energy loss per unit path length due to atomic displacements as a particle traverses a material. The common NIEL unit is MeV∙cm2/g of material.

Non-recoverable SEE – single event effects without mitigation or protection schemes (generally applies to unit/box-level and above)

Recoverable SEE – non-destructive single event effects (generally applies to unit/box-level assessments and above)

Single Event Burnout (SEB) - An event in which a single energetic-particle strike through a high electric field induces a localized high-current state in the device, resulting in catastrophic device failure or in permanent degradation that is usually characterized by a significant increase in leakage current that exceeds the manufacturer’s maximum specification.

Single Event Effect (SEE) - any measurable effect to a circuit due to a single particle strike, commonly an ion or a neutron-induced secondary ion. This includes, but is not limited to, single event upsets (SEUs), single event transients (SETs), single hard errors (SHEs), single event latchups (SELs), single event functional interrupts (SEFIs), single event burnouts (SEBs), single event gate ruptures (SEGRs), and single event dielectric ruptures (SEDRs).

Single Event Functional Interrupt (SEFI) - a condition that causes loss of device functionality due to a change induced in a critical portion of a device, commonly a control structure, configuration file, or mode register. It generally requires a device reset or a re‑initialization to resume normal device operations, but for many devices, a power cycle is necessary to initiate a full device reset to resume normal operations. A device undergoing a SEFI may simply be non-responsive or may have a sustained high-current state as it is no longer operating as designed.

Single Event Gate Rupture (SEGR) - an event in which a single energetic-particle strike results in a breakdown and subsequent conducting path through the gate oxide of a MOSFET, MOS capacitor, or floating-gate memory. An SEGR is manifested by an increase in gate leakage current and can result in either the permanent degradation or the complete failure of the device.

Single Event Latchup (SEL) - a condition that may cause device failure due to a single event induced high current state associated with the turn-on of a real or parasitic thyristor that creates a short circuit between two power supply rails. A SEL may or may not cause permanent device damage but requires power cycling of the device to resume normal device operations. In addition, SEL that appear recoverable may suffer hidden degradation and must be evaluated for

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latent damage (device does not fail from the immediate single particle event, but reliability is degraded, and premature failure may occur). Guidance on radiation test and failure analysis of SEL-induced latent damage is defined in NASA Alert NA-GSFC-2005-05.

Single Event Transient (SET) – a temporary glitch or deviation from expected operation caused by one particle, with a subsequent return to normal operating behavior.

Single Event Upset (SEU) - a change of state induced by an energetic particle such as a cosmic ray or proton in a device, such as a bit flip in memory. These are “soft” errors in that a reset or rewriting of the device will usually return the device to normal behavior thereafter.

Single Hard Error (SHE) - a SEU that causes a permanent change to the operation of a device.

An example is a stuck bit in a memory device.

Single-Bit Upset (SBU) and Multiple Bit Upset (MBU) – a distinction between events that upset a single circuit node (like a memory cell) and those that upset multiple nodes (or memory cells) at once.

Threshold LET (LETth) - the maximum LET at which no SEE is observed.

Total Ionizing Dose (TID) – the mean energy deposited by ionizing radiation in a device region divided by the mass of the region. This is often given in units of rad(Si), where 1 rad(Si) = 100 erg deposited per gram of silicon.

5.1 Reference Documents / Standards

• IRENE AP9/AE9 trapped proton and electron model

• ESP-PSYCHIC solar particle model

• SHIELDOSE-2 shielding transport model

• NIEL (Non-Ionizing Energy Loss) model

• ISO-15390 International standard of Galactic Cosmic Rays

• CREME96 October 1989 solar particle event