ISO 17520:2016

Space environment (natural and artificial) - Cosmic ray and solar energetic particle penetration inward the magnetosphere - Method of determination of the effective vertical cut-off rigidity

ISO 17520:2016 describes the effective vertical cut-off rigidities of charged particles for near-Earth space and establishes principal requirements for their calculation. In Annex A, the calculation technique is verified using a typical example. This International Standard can be used to develop calculation techniques based on different models of Earth's geomagnetic field.[1] The techniques are useful for determination of penetrating into the Earth's magnetosphere by charged particle fluxes, as well as for test and estimations of the impact on spacecraft and other equipment in the near-Earth space. This International Standard is valid for calculating the particle penetration by any of the component of interplanetary charged particles (Galactic, Solar, and Anomalous) with rigidities above 0,2 GV. The main goals of the present standardization for the determination of the effective vertical geomagnetic cut-off rigidities are as follows: - provide an unambiguous procedure for calculation of the cut-off rigidities inside of the Earth's magnetosphere reflecting dependences on geomagnetic disturbances and local time; - provide means of estimation of the impact of charged particle fluxes in interpretation and analysis of space experiments; - provide efficient calculations of the transmission functions of low-altitude orbits of spacecraft and manned space-station; - determine impact of solar energetic particle flux on spacecraft instrumentation and astronauts using results of independent online measurement of interplanetary particle fluxes.

Systèmes spatiaux (naturel et artificiel) — Rayons cosmiques et pénétration de particule énergétique solaire dans la magnétosphère — Méthode de détermination de la rigidité de coupure verticale effective

General Information

• Status: Withdrawn
• Publication Date: 19-Apr-2016
• 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 - Space systems and operations
• Current Stage: 9599 - Withdrawal of International Standard
• Start Date: 06-Mar-2024
• Completion Date: 13-Dec-2025

Relations

• Revised: ISO 17520:2024 - Space environment (natural and artificial) - Cosmic ray and solar energetic particle penetration inward the magnetosphere - Method of determination of the effective vertical cut-off rigidity
• Effective Date: 06-Jun-2022

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 17520
First edition
2016-04-01
Space environment (natural and
artificial) — Cosmic ray and solar
energetic particle penetration inward
the magnetosphere — Method of
determination of the effective vertical
cut-off rigidity
Systèmes spatiaux (naturel et artificiel) — Rayons cosmiques et
pénétration de particule énergétique solaire dans la magnétosphère
— Méthode de détermination de la rigidité de coupure verticale
effective
Reference number
©
ISO 2016
ISO 17520:2016(E)
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© ISO 2016, Published in Switzerland
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ii © ISO 2016 – All rights reserved

ISO 17520:2016(E)
Contents  Page
Foreword .iv
Introduction .v
1 Scope . 1
2  Terms and definitions . 1
3  General concepts and assumptions . 3
3.1 Determination of effective vertical cut-off rigidity . 3
3.2 Models of the employed geomagnetic field . 3
3.3 Effective vertical cut-off rigidity databases (libraries). 4
3.4 Method for effective vertical cut-off data generalization . 4
4  Model requirements . 4
4.1 General . 4
4.2 Parameterization . 4
Annex A (informative) Effective vertical cut-off determination procedure .5
Annex B (informative) Presentation of the results . 6
Annex C (informative) Method for effective vertical cut-off data generalization for
different conditions . 7
Bibliography .11
ISO 17520:2016(E)
Foreword
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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 2016 – All rights reserved

ISO 17520:2016(E)
Introduction
This International Standard describes principal requirements for determination of the effective
vertical cut-off rigidity of penetration of charged particles inward the Earth’s magnetosphere. This
International Standard establishes procedure for calculation of the effective vertical cut-off rigidities
for altitude, geographical coordinates (latitude and longitude), and for conditions of geomagnetic
disturbances described by the Kp-index, as well as for local time. The model that satisfies these
requirements is described in the Annex through a series of examples. This International Standard
is intended for estimation of penetration into the Earth’s magnetosphere by charged particle fluxes
from interplanetary space, which is important for developing and testing of influence to hardware
and biological objects onboard spacecraft and orbital stations. Procedures for performing simplified
calculations of rigidities are proposed.
INTERNATIONAL STANDARD  ISO 17520:2016(E)
Space environment (natural and artificial) — Cosmic
ray and solar energetic particle penetration inward the
magnetosphere — Method of determination of the effective
vertical cut-off rigidity
1 Scope
This International Standard describes the effective vertical cut-off rigidities of charged particles
for near-Earth space and establishes principal requirements for their calculation. In Annex A, the
calculation technique is verified using a typical example. This International Standard can be used to
[1]
develop calculation techniques based on different models of Earth’s geomagnetic field. The techniques
are useful for determination of penetrating into the Earth’s magnetosphere by charged particle fluxes, as
well as for test and estimations of the impact on spacecraft and other equipment in the near-Earth space.
This International Standard is valid for calculating the particle penetration by any of the component
of interplanetary charged particles (Galactic, Solar, and Anomalous) with rigidities above 0,2 GV. The
main goals of the present standardization for the determination of the effective vertical geomagnetic
cut-off rigidities are as follows:
— provide an unambiguous procedure for calculation of the cut-off rigidities inside of the Earth’s
magnetosphere reflecting dependences on geomagnetic disturbances and local time;
— provide means of estimation of the impact of charged particle fluxes in interpretation and analysis
of space experiments;
— provide efficient calculations of the transmission functions of low-altitude orbits of spacecraft and
manned space-station;
— determine impact of solar energetic particle flux on spacecraft instrumentation and astronauts
using results of independent online measurement of interplanetary particle fluxes.
2  Terms and definitions
For the purposes of this document, the following terms and definitions apply.
2.1
internal (main) magnetic field
magnetic field produced by the sources inside the Earth’s core
Note 1 to entry: See ISO 16695.
Note 2 to entry: It can be presented by the International Geomagnetic Reference Field (IGRF) model.
2.2
International Geomagnetic Reference Field model
IGRF model
geomagnetic reference field in the form of a series of spherical harmonic functions
Note 1 to entry: See Reference [2].
Note 2 to entry: The expansion coefficients undergo very slight changes in time.
Note 3 to entry: The International Association of Geomagnetism and Aeronomy (IAGA) is responsible for IGRF
model development and modifications and approves its coefficients every five years. The internal magnetic field
is not the subject of this International Standard.
ISO 17520:2016(E)
2.3
external (magnetospheric) magnetic field
magnetic field produced by magnetospheric sources
[3] [4][5]
Note 1 to entry: It can be described by different models, e.g. Tsyganenko-89 and more recent models.
2.4
Tsyganenko-89 geomagnetic field model
model described in Reference
[SOURCE: 3]
2.5
Geomagnetic field
sum of internal and external magnetic fields
2.6
particle charge Z
−19
charge Z of a particle is equal to +ne, (n = 1, 2, 3,….), where e is the value of electron charge (1,60 × 10 C).
2.7
particle magnetic rigidity
magnetic rigidity of particle R is related to particle momentum p and its charge by:
R = pc/Z
where c is the speed of light, and Z is the charge of a particle
Note 1 to entry: The magnetic rigidity of protons and nuclei is related to the particle’s energy as
A
R=+EE( 2M )
Z
where E is the kinetic energy in GeV/u, A is the particle’s mass in amu, and M is the rest mass of proton equal to
0,931 GeV.
2.8
cut-off rigidity
location of a transition, in rigidity space, from allowed to forbidden trajectories as rigidity is decreasing
2.9
lower cut-off rigidity
R
L
access of particles of all rigidity values lower than the lower cut-off rigidity is forbidden for penetration
from outside of the Earth’s magnetic field
Note 1 to entry: R is the calculated lowest cut-off value, i.e. the rigidity value of the lowest allowed/forbidden
L
transition obtained in computer simulations.
2.10
main (upper) cut-off rigidity
R
U
access of particles of all rigidity values higher than the main cut-off rigidity is allowed for penetration
from outside of the Earth’s magnetic field
Note 1 to entry: R is the rigidity value of the calculated upper cut-off value, i.e. the rigidity value of the highest
U
allowed/forbidden transition obtained in computer simulations.
2.11
penumbra
rigidity range lying between the main (upper) and the lower cut-off rigidities
2 © ISO 2016 – All rights reserved

ISO 17520:2016(E)
2.12
effective cut-off rigidity
R
eff
total effect of the penumbral structure in a given direction may be represented for a number of
purposes, by the “effective cut-off rigidity”, a single numerical value which specifies the equivalent total
accessible cosmic radiation within the penumbra in a specific direction
2.13
effective vertical cut-off rigidity
EVRC
effective cut-off rigidity value for a particle arriving to a fixed point in the vertical direction (radially to
the centre of the Earth)
2.14
index of magnetosphere disturbance
K
three-hour quasi-logarithmic local index of geomagnetic activity relative to on assumed quiet-day
curve for a specific recording site
Note 1 to entry: The range is from zero to nine. The K index measures the deviation of the most disturbed
horizontal component.
2.15
Kp-index
three-hour planetary geomagnetic index of activity based on the K index from 13 stations distributed
around the world
Note 1 to entry: The Kp-index is originally derived at GeoForschungsZentrum in Germany. The web address should
be http://www.gfzpotsdam.de/en/research/organizationalunits/departments/department-2/earthsmagnetic-
field. It is also available at www.swpc.noaa.gov.
2.16
attenuation quotient
Δ(R ,Kp,T)
determines how much the vertical cut-off rigidity value in a real geomagnetic field for a given Kp-index,
at a local time T, decreased relative to values calculated with the IGRF model (R )
Note 1 to entry: Some of these terms are also defined in Reference [6].
3  General concepts and assumptions
3.1  Determination of effective vertical cut-off rigidity
The geomagnetic cut-off rigidities are determined by tracing particle trajectories in t
...