ISO 17761:2015

Space environment (natural and artificial) - Model of high energy radiation at low altitudes (300 km to 600 km)

ISO 17761:2015 describes the fluxes of charged particles for near-Earth space on base of the PAMELA experiment data. This International Standard can be used to calculate fluxes of protons with energy more than 100 MeV up to geomagnetic cut-off rigidity at low altitudes (300 km to 600 km). The main goal of this International Standard is determining the impact of energetic charged particle flux upon spacecraft instrumentation and astronauts.

Environnement spatial (naturel et artificiel) — Modèle de radiations à énergie élevée à basses altitudes (300 km à 600 km)

General Information

• Status: Published
• Publication Date: 09-Nov-2015
• ICS: 49.140 - Space systems and operations
• Technical Committee: ISO/TC 20/SC 14 - Space systems and operations
• Drafting Committee: ISO/TC 20/SC 14/WG 4 - Space environment (natural and artificial)
• Current Stage: 9093 - International Standard confirmed
• Start Date: 20-Jul-2021
• Completion Date: 13-Dec-2025

Overview

ISO 17761:2015 is an international standard published by the International Organization for Standardization (ISO) focused on the characterization of high energy radiation in near-Earth space. Specifically, it provides a comprehensive model of charged particle fluxes-primarily protons with energies exceeding 100 MeV-at low altitudes ranging from 300 km to 600 km above Earth’s surface. The standard utilizes data primarily from the PAMELA experiment, a satellite mission that provided precise measurements of cosmic rays and trapped radiation.

The core purpose of ISO 17761:2015 is to accurately estimate the fluxes of high-energy charged particles in Earth's magnetosphere to assess their impact on spacecraft instrumentation and astronaut safety. This is crucial for designing resilient spacecraft systems and planning manned space missions.

Key Topics

• Charged Particle Fluxes: Describes proton flux with energies above 100 MeV, extending to the geomagnetic cut-off rigidity at low Earth orbit altitudes, integrating both natural and artificial space radiation sources.
• PAMELA Data Integration: Uses innovative particle detection data from the PAMELA space mission, enhancing previous radiation models with high-precision measurements.
• Geomagnetic Cut-Off Rigidity: Accounts for the magnetic rigidity threshold below which charged cosmic rays are deflected by Earth's magnetic field, defining regions where primary cosmic rays are either allowed or blocked.
• Geomagnetic Coordinates (L-shell and B): Utilizes geomagnetic reference frames to map radiation flux distributions in the magnetosphere.
• Albedo Trapped Particles: Includes secondary charged particles (such as protons and electrons) generated by cosmic ray interaction with Earth's atmosphere and trapped by the geomagnetic field, including detailed consideration of phenomena like the South Atlantic Anomaly (SAA).
• Radiation Environment Modeling: Provides data tables and smoothed flux profiles for protons, electrons, and positrons as functions of energy and geomagnetic location for the 2006–2009 epoch.

Applications

• Spacecraft Design: Engineers can use ISO 17761:2015 to predict the radiation environment that spacecraft electronics and materials will encounter in low Earth orbit (LEO), helping mitigate risks of radiation damage.
• Astronaut Safety: Critical for mission planners to estimate astronaut exposure to high-energy radiation during missions at altitudes between 300 km and 600 km, facilitating protective measures and safety protocols.
• Radiation Shielding Analysis: Supports the development of better radiation shielding solutions by providing detailed flux data for high-energy protons and electrons encountered on LEO spacecraft.
• Space Mission Planning: Enables accurate assessments to ensure reliability of satellite instruments and communication systems in varying geomagnetic environments, particularly near sensitive regions such as the SAA.
• Scientific Research: Serves as a reference for astrophysicists and space scientists studying cosmic ray interactions and trapped radiation dynamics in Earth’s magnetosphere.

Related Standards

• ISO 15390 – Galactic Cosmic Ray Model: Complements ISO 17761 by modeling cosmic ray flux outside Earth's magnetosphere, essential for understanding primary cosmic radiation impacting satellites.
• ISO 16695 – Geomagnetic Reference Models: Provides geomagnetic field models vital for calculating particle trajectories and cut-off rigidities that are integral to ISO 17761's flux estimations.
• ISO 22009 – Earth's Magnetospheric Magnetic Field Model: Offers foundational geomagnetic field data used in conjunction with charged particle flux modeling.
• NASA AP-8 and AE-8 Models: Though based on legacy data, these models have historically been used for trapped proton and electron radiation estimates; ISO 17761 improves upon them with modern PAMELA data.
• PAMELA Mission Publications: The experimental results and data interpretations from the PAMELA collaboration form the empirical basis for ISO 17761.

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Using ISO 17761:2015 supports accurate, data-driven analysis of the natural and artificial space radiation environment at low Earth orbit altitudes. By incorporating cutting-edge measurements of high-energy charged particles, this standard ensures that space systems and astronaut health considerations are informed by the latest scientific knowledge, enhancing mission success and safety in the challenging near-Earth space environment.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 17761
First edition
2015-11-15
Space environment (natural and
artificial) — Model of high energy
radiation at low altitudes (300 km to
600 km)
Environnement spatial (naturel et artificiel) — Modèle de radiations
à énergie élevée à basses altitudes (300 km à 600 km)
Reference number
©
ISO 2015
ISO 17761:2015(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2015, Published in Switzerland
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ii © ISO 2015 – All rights reserved

ISO 17761:2015(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2  Terms and definitions . 1
3 General concepts and assumptions . 2
Annex A (informative) Tables for proton and electron fluxes . 3
Bibliography . 6
ISO 17761:2015(E)
Foreword
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Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 20, Aircraft and space vehicles, Subcommittee
SC 14, Space systems and operations.
iv © ISO 2015 – All rights reserved

ISO 17761:2015(E)
Introduction
The International Standard is intended for the estimation of high energy charged particle fluxes at
low altitudes (300 km to 600 km) in the Earth’s magnetosphere. Detailed information on high energy
charged particle fluxes is essential for developing spacecrafts and spacecraft equipment.
[1]
High energy galactic cosmic rays approaching the Earth interact with the atmosphere resulting
in a production of secondary particles. The flux of secondary particles is composed mainly by
electrons, protons, neutrons and gamma-rays which execute their trajectories in the Earth’s magnetic
[2]
field. An appreciable fraction of charged secondary particles with rigidity less than geomagnetic cut-
[3]
off can travel backward in space along the Earth’s magnetic field lines and can reach the satellite
altitudes forming a high energy radiation halo in the Earth vicinity. The other fraction of secondary
protons is trapped by geomagnetic field for years forming the inner radiation belt. These protons with
kinetic energies greater than some tens of MeV mainly originated from the β-decay of albedo neutrons
[4]
according to the so-called “Cosmic Ray Albedo Neutron Decay” (CRAND) mechanism. According
to this mechanism, the Earth is surrounded in its equatorial region by shaped ring of high radiation.
Because of a shift of geomagnetic dipole with respect to the Earth centre, in South Atlantic Anomaly
(SAA) trapped particles are observed at low altitudes approximately 300 km.
On the basis of the data primarily taken from mid-sixties to early seventies of the last century, the model
[4]
of the Earth’s trapped proton radiation has been provided by the NASA AP-8 models. Significant
improvements of radiation environment modelling in low Earth orbit (LEO) was carried out thanks
[5][6][7]
to data from satellite experiments, such as CRRES, SAMPEX/PET and the TIROS/NOAA series.
These models can be used for estimations of radiation environment for energies below ~100 МeV with
some procedures taking into account secular variations of the geomagnetic filed and drift of SAA for
current epoch (e.g. Reference [8]).
Modern, more accurate measurements of the high energy (Ekin above ~100 MeV) cosmic ray radiation
[9]
in LEO have been reported by the PAMELA mission. These new measurements including trapped
component and charged albedo components are the basis of this International Standard.
INTERNATIONAL STANDARD  ISO 17761:2015(E)
Space environment (natural and artificial) — Model of high
energy radiation at low altitudes (300 km to 600 km)
1 Scope
This International Standard describes the fluxes of charged particles for near-Earth space on base of
the PAMELA experiment data. This International Standard can be used to calculate fluxes of protons
with energy more than 100 MeV up to geomagnetic cut-off rigidity at low altitudes (300 km to 600 km).
The main goal of this International Standard is determining the impact of energetic charged particle
flux upon spacecraft instrumentation and astronauts.
2  Terms and definitions
For the purposes of this document, the following terms and definitions apply.
2.1
International Geomagnetic Reference Field model
IGRF model
[10]
geomagnetic reference field in the form of a series of spherical harmonic functions
Note 1 to entry: The International Association of Geomagnetism and Aeronomy (IAGA) is responsible for IGRF
[10]
model development and modifications and approves its coefficients every five years.
2.2
particle magnetic rigidity
magnetic rigidity of particle, R, is related to particle momentum, p, and its charge, Z, by:
R = pc/Z
[3]
where c is the speed of light.
2.3
cut-off rigidity
location of a transition for primary charged cosmic ray particles, in rigidity space, from allowed to
[3]
forbidden trajectories as rigidity is decreased
2.4
geomagnetic coordinates L and B
used to map differential fluxes j of energetic geomagnetically trapped particles
Note 1 to entry: B is absolute value of geomagnetic field in the point of observation. In the dipole approximation
of the geomagnetic field, L-shell is distance to magnetic field line in equatorial plane.
[11]
Note 2 to entry: Geomagnetic coordinates L-shell and B are introduced by MacIlwain.
2.5
Albedo trapped particles
part of cosmic ray charged radiation with rigidity below geomagnetic cut-off produced in interactions
of high energy cosmic rays with residual atmosphere of the Earth which execute their trajectories in
the Earth magnetic field
ISO 17761:2015(E)
3 General concepts and assumptions
This International
...