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
• Completion Date: 20-Jul-2021

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 17761:2015(E)
ISO 2015
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ISO 17761:2015(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2015, Published in Switzerland

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ii © ISO 2015 – All rights reserved
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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 2015 – All rights reserved iii
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ISO 17761:2015(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

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electrotechnical standardization.

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described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

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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
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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.

© ISO 2015 – All rights reserved v
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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
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ISO 17761:2015(E)
3 General concepts and assumptions
This International
...