ISO 24411:2022

Space systems - Micro-vibration testing

This document specifies requirements for the implementation of spacecraft level micro-vibration tests on space systems to be considered by test providers, including test designers and test engineers. It also gives guidance for spacecraft designers and interested parties. The spacecraft level micro-vibration test is applicable to space systems which contain payload equipment sensitive to the micro-vibration environment which only induced by the internal disturbance sources on-orbit, e.g. for the purpose of earth observation, space telescopes, optical experiments, telecommunication.

Systèmes spatiaux — Essais de microvibration

General Information

• Status: Published
• Publication Date: 09-Oct-2022
• 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 2 - System requirements, verification and validation, interfaces, integration, and test
• Current Stage: 6060 - International Standard published
• Start Date: 10-Oct-2022
• Due Date: 10-Sep-2022
• Completion Date: 10-Oct-2022

Overview - ISO 24411:2022 (Space systems - Micro-vibration testing)

ISO 24411:2022 establishes requirements and guidance for spacecraft-level micro‑vibration testing. It defines how test providers (test designers and test engineers) should plan and implement ground tests that reproduce on‑orbit micro‑vibration caused by internal disturbance sources. The standard applies to space systems with payloads sensitive to micro‑vibration (e.g., earth observation, space telescopes, optical experiments, telecommunications) where disturbances originate from internal equipment only.

Key topics and technical requirements

• Test purpose: Verify dynamic behaviour in the micro‑vibration environment by measuring transfer characteristics, modal parameters and payload responses.
• Preliminary analysis: Identify sensitive payloads and dominant internal disturbance sources; decide if spacecraft‑level testing is required and derive test planning inputs.
• Disturbance sources: Classification and characteristics of internal sources (see informative Annex A) that must be replicated or simulated during tests.
• Test types:
  • Transfer function measurement - determine transmissibility from source to payload.
  • Modal survey test - extract spacecraft modal parameters to update analysis models.
  • Micro‑vibration response measurement - quantify payload performance under disturbance.
• Test equipment and configuration: Guidance on boundary simulation, analogue exciters, measurement sensors, data acquisition, and FFT‑based processing. Emphasis on controlling background noise and ensuring adequate signal‑to‑noise ratio (S/N).
• Environment and safety: Laboratory requirements, background noise limits and safety considerations during test execution.
• Test flow and reporting: Stepwise procedure from pre‑test activities through implementation, interruption handling, data evaluation and final test report content.
• Tailoring: Requirements may be tailored to specific missions while maintaining the objective of verifying micro‑vibration performance.

Practical applications

• Validate that high‑stability payloads meet pointing and position stability requirements under expected on‑orbit micro‑vibration.
• Update structural and dynamic models using modal survey results to improve prediction accuracy.
• Support mission acceptance for optical instruments, high‑precision antennas and imaging payloads impacted by milli‑g to micro‑g level dynamics.

Who should use this standard

• Test providers: laboratories, test designers and test engineers conducting spacecraft micro‑vibration campaigns.
• Spacecraft designers and systems engineers: to inform payload placement, disturbance mitigation and verification planning.
• Project managers and mission assurance: to define verification strategies for sensitive payloads.

Related standards

• ISO 14620‑1 - Space systems - Safety requirements
• ISO 15864:2021 - General test methods for spacecraft, subsystems and units
• ISO 17566:2011 - General test documentation

Keywords: ISO 24411:2022, micro‑vibration testing, spacecraft testing, transfer function, modal survey, payload sensitivity, space systems.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 24411
First edition
2022-10
Space systems — Micro-vibration
testing
Systèmes spatiaux — Essais de microvibration
Reference number
© ISO 2022
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
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Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword .v
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviated terms.2
5 Test purpose . 2
6 General test information . 3
6.1 Tailoring . 3
6.2 Disturbance sources . 3
6.3 Preliminary analysis . 3
7 Test equipment .3
7.1 Test configuration for transfer function measurement and modal survey test . 3
7.2 Test configuration for response measurement . 4
7.3 Test equipment functional requirements and recommendations . 5
7.3.1 Boundary simulation . 5
7.3.2 Excitation . 7
7.3.3 Measurement, data acquisition and processing . 7
8 Test requirements and recommendations. 8
8.1 General test requirements and recommendations . 8
8.1.1 General . 8
8.1.2 Transfer function measurement. 9
8.1.3 Modal survey test . 9
8.1.4 Micro-vibration response measurement . 9
8.2 Pre-conditions . . 9
8.3 Test article configuration. 9
8.4 Test environment . 10
8.4.1 Laboratory environment requirements . 10
8.4.2 Background noise requirements . 10
8.5 Measurement . 10
8.6 Safety. 10
9 Test flow and procedure .11
9.1 Test flow . 11
9.2 Test procedure . 11
9.2.1 General . 11
9.2.2 Before the test . 12
9.2.3 Test implementation .12
9.2.4 After the test . 14
10 Test interruption and handling .14
10.1 Test interruption . . 14
10.2 Interruption handling . 14
11 Test data and result evaluation .14
11.1 Test data . 14
11.2 Result evaluation . 15
12 Test report .15
Annex A (informative) Typical internal disturbance sources and characteristics .16
Annex B (informative) Guideline of the necessity of spacecraft level micro-vibration test .17
Annex C (informative) Suspension frequencies measurement .18
iii
Bibliography .22
iv
Foreword
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described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
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www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 20, Aircraft and space vehicles,
Subcommittee SC 14, Space systems and operations.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
v
Introduction
Spacecraft on-orbit experience a micro-vibration environment which can induce severe disturbances to
sensitive payload with high pointing stability and/or position stability. It can affect mission success of
payload equipment, e.g. earth observation, space telescopes, optical experiments, telecommunication.
For such applications, it is necessary to verify their resistance to the micro-vibration environment on-
orbit. This verification may be supported by spacecraft level micro-vibration tests on ground. In that
case:
— the vibration transmissibility from the disturbance sources to the sensitive payloads should be
investigated;
— the performance of these payloads under the influence of the relevant disturbance sources should
be identified by response measurements;
— the modal parameters of the spacecraft should be extracted to update the analysis model.
This document specifies contents to meet test requirements. It includes test purpose, general test
information, test equipment, test requirements and recommendations, test flow and procedure, test
interruption and handling, test data and result evaluation, and test reports for spacecraft level micro-
vibration tests.
vi
INTERNATIONAL STANDARD ISO 24411:2022(E)
Space systems — Micro-vibration testing
1 Scope
This document specifies requirements for the implementation of spacecraft level micro-vibration tests
on space systems to be considered by test providers, including test designers and test engineers. It also
gives guidance for spacecraft designers and interested parties.
The spacecraft level micro-vibration test is applicable to space systems which contain payload
equipment sensitive to the micro-vibration environment which only induced by the internal disturbance
sources on-orbit, e.g. for the purpose of earth observation, space telescopes, optical experiments,
telecommunication.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 14620-1, Space systems — Safety requirements — Part 1: System safety
ISO 15864:2021, Space systems — General test methods for spacecraft, subsystems and units
ISO 17566:2011, Space systems — General test documentation
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
micro-vibration environment
dynamic environment on-orbit which is characterized by very low acceleration level compared with the
usual dynamic environment during launch
Note 1 to entry: Micro-vibration environment affects the normal performance or function of sensitive payload
equipment of the spacecraft on-orbit.
Note 2 to entry: Generally, the micro-vibration environment of the sensitive payload equipment on-orbit is in the
[1]
range of micro-g's to milli-g’s, and the frequency range is from a few hertz up to a few hundred hertz .
3.2
background noise
noise coming from sources other than the test signal
[SOURCE: ISO 13472-1:2022, 3.8]
3.3
signal-to-noise ratio
S/N
difference between the level of the nominal useful signal and the level of the background noise (3.2) at
the moment of detection of the useful event
Note 1 to entry: The signal-to-noise ratio is given in decibels.
[SOURCE: ISO 13472-1:2022, 3.9]
3.4
design safety factor
factor by which limit loads are multiplied in order to account for uncertainties and variations that
cannot be analysed or accounted for explicitly in a rational manner
Note 1 to entry: Design safety factor is sometimes referred to as design factor of safety, factor of safety or just
safety factor.
[SOURCE: ISO 10786:2011, 3.15]
4 Symbols and abbreviated terms
FFT fast Fourier transform
FM flight model
LoS line-of-sight
RMS root mean square
S/N signal-to-noise ratio
SADA solar array drive assembly
SM structural model
STM structural/thermal model
5 Test purpose
The main purpose of the spacecraft level micro-vibration test is to verify the dynamic characteristics in
micro-vibration environment. This is achieved by:
— obtaining transfer characteristics from disturbance source to the sensitive payload to verify the
transfer path design through transfer function measurements;
— obtaining modal parameters of the spacecraft through a modal survey test, in order to update the
analysis model;
— obtaining the micro-vibration response of sensitive payload equipment through response
measurements.
Usually, the verification of the dynamic characteristics in a micro-vibration environment is based on a
combination of analytical prediction and test.
6 General test information
6.1 Tailoring
Requirements of this document may be tailored to fulfil the objectives of the test.
6.2 Disturbance sources
Disturbance sources can be classified as external sources and internal sources. External sources can be
found in the space environment, e.g. eclipse entry and exit. Internal sources can be found from within
the spacecraft.
Annex A presents typical internal disturbance sources and their characteristics.
6.3 Preliminary analysis
A preliminary micro-vibration analysis shall be conducted before the spacecraft level micro-vibration
test. The objectives of the preliminary analysis are:
a) to identify the payloads sensitive to micro-vibration;
b) to identify the main disturbance sources on-orbit;
c) to decide whether a spacecraft level micro-vibration test for a specified spacecraft is necessary.
Annex B may be considered to decide whether spacecraft level micro-vibration tests are necessary
or not for the spacecraft with pointing stability as the sensitive index, depending on the nature and
characteristics of the mission.
In cases where spacecraft level micro-vibration testing is decided to be necessary, modelling and
analysis of spacecraft dynamics should be done before test for test planning and the following tasks
shall be executed:
— Obtain the prediction results to be used for test planning and specification.
— Define the configuration of the test article under the consideration that the test configuration can
differ from the flight configuration.
— Determine the dynamic characteristics of the disturbance sources to be replaced by analogue
exciters in the test configuration.
— Define the test frequency range according to the sensitive frequency range of the sensitive payloads.
— Evaluate the influence of boundary simulation equipment.
7 Test equipment
7.1 Test configuration for transfer function measurement and modal survey test
The test configuration for the transfer function measurement and modal survey test shall:
a) provide approximated “free-free” boundary conditions for the test article;
b) apply the excitation force to the pre-defined excitation points in the test article;
c) measure, acquire and process response signals;
d) obtain transfer functions from the response signals with the excitation signal as the reference;
e) obtain modal parameters based on the transfer functions, so as to update the analysis model if
needed or requested.
NOTE The “free-free” boundary conditions can be chosen and justified so that it remains representative of
the dynamic characteristics of the test article on orbit flight conditions.
An example of test configuration is shown in Figure 1.
Figure 1 — Test configuration for transfer function measurements and modal survey test
7.2 Test configuration for response measurement
The test configuration for response measurement shall:
a) provide approximated “free-free” boundary conditions for the test article;
b) excite the test article by disturbance sources or analogue exciters;
c) measure, acquire and process response signals (typical sensors are accelerometers, displacement
sensors, force sensors, angular sensors).
NOTE The “free-free” boundary conditions can be chosen and justified so that it remains representative of
the dynamic characteristics of the test article on orbit flight conditions.
An example of test configuration is shown in Figure 2.
Figure 2 — Test configuration for response measurement of micro-vibration
7.3 Test equipment functional requirements and recommendations
7.3.1 Boundary simulation
The test configuration shall simulate the on-orbit dynamic conditions as close as possible in order to
get reliable estimates for the expected on-orbit performances. In particular, the test article shall be in
a quasi “free-free” boundary condition and the gravity forces acting on the structure and surrounding
air effects shall be minimized.
The requirements and recommendations for the boundary simulation equipment are as follows:
a) The boundary simulation equipment shall provide the function of suspension and safety protection
for the test article.
b) Suspension frequencies, which are the first six rigid body frequencies of the system composed of
boundary simulation equipment and the test article, should be lower than 25 % of the first elastic
modal frequency of the test article under the free-free boundary condition.
c) The attached mass moving synchronously with the test article should be sufficiently less than the
mass of the test article (e.g. less than 5 % of the mass of the test article) to ensure that its dynamic
characteristics are unchanged as far as possible.
d) The influence of the boundary simulation equipment on the dynamic characteristics of the test
article shall be analysed.
e) The design safety factor of boundary simulation equipment under static load induced by the gravity
force of the test article shall meet the requirements of the customers.
f) One end of the boundary simulation equipment shall match the interface of the test article, and the
other end shall match the ground base or coping of the laboratory.
NOTE The “free-free” boundary conditions can be chosen and justified so that it remains representative of
the dynamic characteristics of the test article
...