ISO 23835:2022
(Main)Space Systems — Mechanism design and verification
Space Systems — Mechanism design and verification
This document establishes requirements for the design, material selection and characterization, fabrication, testing and inspection of all space mechanisms on spacecraft and payloads to meet the mission performance requirements. This document does not cover the requirements for mechanisms on expendable and reusable launch vehicles. Applicability of the requirements contained in this document to launch vehicle mechanisms is a decision left to the individual launch vehicle project. This document applies specifically to all moving mechanisms used in spacecraft during all phases of the mission, with the exception of engines and thermal protection systems.
Systèmes spacieux — Conception et vérification des mécanismes
General Information
Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 23835
First edition
2022-04
Space Systems — Mechanism design
and verification
Systèmes spacieux — Conception et vérification des mécanismes
Reference number
ISO 23835:2022(E)
© ISO 2022
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ISO 23835:2022(E)
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© ISO 2022
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ISO 23835:2022(E)
Contents Page
Foreword .v
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Fundamental requirements . 4
4.1 System performance . 4
4.2 Mission . 4
4.3 Function . 4
5 Design requirements .4
5.1 Interfaces . 4
5.2 Environmental design . 5
5.2.1 General . 5
5.2.2 Ground environment . 5
5.2.3 Launch vehicle flight environment . 5
5.2.4 Orbital environment. 5
5.3 Parts and materials . 5
5.3.1 General . 5
5.3.2 Requirements for parts . 6
5.3.3 Requirements for materials . 6
5.4 Mechanism design . 6
5.4.1 Accuracy control design . 6
5.4.2 Driving capability design . 7
5.4.3 Design life . 7
5.4.4 Tribology . 7
5.4.5 Major mechanical components . 8
5.4.6 Other requirements . 8
5.5 Structural design . 9
5.5.1 General requirements related to structural design . 9
5.5.2 Allowable mechanical properties of structural materials . 9
5.5.3 Margin of safety . 9
5.5.4 Stiffness design . 9
5.6 Thermal design . 9
5.7 Electrical design . 9
5.7.1 Electrical design . 9
5.7.2 Electrical wires . . 10
5.7.3 Electric connectors . 10
5.7.4 Insulation . 10
5.7.5 Grounding . 10
5.7.6 Deformation of wiring . 10
5.8 General requirements . 10
5.8.1 Safety . 10
5.8.2 Dependability . 10
5.8.3 Quality assurance . 11
5.8.4 Configuration . 11
5.8.5 Redundancy . 11
5.8.6 Operability . 11
5.8.7 Maintainability . 11
5.8.8 Interchangeability . 11
5.8.9 Fool-proof design . 11
5.8.10 Other requirements .12
6 Verification .12
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ISO 23835:2022(E)
6.1 General .12
6.2 Verification by analysis . 12
6.2.1 General .12
6.2.2 Identification of worst-case conditions . .13
6.2.3 Thermal analysis . 13
6.2.4 Structural analysis .13
6.2.5 Function and performance analysis . 13
6.2.6 Analysis of torque/force margin . 14
6.2.7 Shock generation and susceptibility . 14
6.2.8 Generated disturbance . 14
6.2.9 Lubrication analysis . 14
6.2.10 Life analysis . 14
6.2.11 Magnetic or electromagnetic analysis . 14
6.2.12 Radiation analysis . 14
6.2.13 Electrical parts stress analysis . 14
6.3 Verification by test . 15
6.3.1 General .15
6.3.2 Development tests .15
6.3.3 Qualification tests . 15
6.3.4 Acceptance tests . 16
6.3.5 Life test . 17
Annex A (informative) Driving capability design (torque/force margin) .18
Annex B (informative) Life test duration factors .27
Annex C (informative) Recommended best practices for model and simulations (M&S) .31
Bibliography .32
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ISO 23835:2022(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
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
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
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
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.
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ISO 23835:2022(E)
Introduction
Mechanisms are important elements of spacecraft and its payloads. A mechanism failure can cause the
loss of human lives for manned space systems or jeopardize the intended mission for unmanned space
systems.
Currently, there is no international standard that covers all the aspects that can be used for space
flight moving mechanisms such as rotating machineries, solar array drive mechanism, paddle hinge
mechanism, latch mechanism.
The purpose of this document is to establish general requirements for mechanisms. It provides
the uniform requirements necessary to minimize the duplication of effort for resolving technical
barrier, considering the differences between approaches taken by the participating nations and
their commercial space communities in developing mechanisms. In addition, the use of agreed-upon
standards will facilitate cooperation and communication among space programmes.
This document, when implemented for a particular space system, ensures high confidence in achieving
safe and dependable operation in all phases of its planned mission.
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INTERNATIONAL STANDARD ISO 23835:2022(E)
Space Systems — Mechanism design and verification
1 Scope
This document establishes requirements for the design, material selection and characterization,
fabrication, testing and inspection of all space mechanisms on spacecraft and payloads to meet the
mission performance requirements. This document does not cover the requirements for mechanisms on
expendable and reusable launch vehicles. Applicability of the requirements contained in this document
to launch vehicle mechanisms is a decision left to the individual launch vehicle project.
This document applies specifically to all moving mechanisms used in spacecraft during all phases of
the mission, with the exception of engines and thermal protection systems.
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 10786, Space systems — Structural components and assemblies
ISO 14302, Space systems — Electromagnetic compatibility requirements
ISO 15864, Space systems — General test methods for spacecraft, subsystems and units
ISO 21886, Space systems — Configuration management
ISO 23135, Space systems — Verification program and management process
ISO 23460, Space projects — Programme management — Dependability assurance requirements
ISO 24113, Space systems — Space debris mitigation requirements
ISO 27025, Space systems — Programme management — Quality assurance requirements
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
mechanism
assembly of parts that are linked together to enable a relative motion
3.2
outgassing
evolution of gaseous species from a material, usually in a vacuum
Note 1 to entry: Outgassing also occurs in higher-pressure environments.
[SOURCE: ISO 15388:2012, 3.1.34]
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ISO 23835:2022(E)
3.3
interface
mechanical, thermal, electrical, or operational common boundary between two elements of a system
[SOURCE: ISO 10795:2019, 3.132]
3.4
acceptance test
required formal test conducted on flight hardware to ascertain that the materials, manufacturing
processes, and workmanship meet specifications and that the hardware is acceptable for intended
usage
[SOURCE: ISO 10786:2011, 3.2]
3.5
contamination
introduction of any undesirable molecular or particulate matter (including microbiological matter) into
an item or into the environment of interest
[SOURCE: ISO 10795:2019, 3.62]
3.6
lubrication
use of specific material surface properties or an applied material between two contacting or moving
surfaces in order to reduce friction, wear or adhesion
3.7
redundancy
〈design property of a system〉 existence of more than one means for performing a function
Note 1 to entry: The additional means of performing the function may be intentionally different (diverse) to
reduce the potential for common mode failures.
[SOURCE: ISO 10795:2019, 3.196]
3.8
debris
fragment such as abrasion powders produced by the operation of mechanism (3.1) parts
Note 1 to entry: See also space debris (3.18).
3.9
tribology
discipline that deals with the design, friction, wear and lubrication (3.6) of interacting surfaces in
relative motion to each other
3.10
qualification test
required formal contractual test used to demonstrate that the design, manufacturing, and assembly
have resulted in hardware designs conforming to specification requirements
[SOURCE: ISO 10795:2019, 3.187]
3.11
maintainability
〈of an item〉 ability to be retained in, or restored to a state in which it can perform as required, under
given conditions of use and maintenance
Note 1 to entry: Given conditions of use may include storage.
Note 2 to entry: Given conditions of maintenance include the procedures and resources for use.
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ISO 23835:2022(E)
Note 3 to entry: Maintainability may be quantified using such measures as mean time to restoration, or the
probability of restoration within a specified period of time.
[SOURCE: ISO 10795:2019, 3.144]
3.12
misalignment
geometric position error between machine elements and parts
EXAMPLE Translational displacement, inclination, torsion.
3.13
mission
set of tasks, duties or functions to be accomplished by an element
[SOURCE: ISO 10795:2019, 3.154]
3.14
latching
locking
intentional constraining of one or more previously unconstrained degrees of freedom which cannot be
released without specific action
3.15
model
physical or abstract representation of relevant aspects of an item or process that is put forward as a
basis for calculations, predictions, or further assessment
Note 1 to entry: The term “model” can also be used to identify particular instances of the product, e.g. flight
model.
[SOURCE: ISO 10795:2019, 3.155]
3.16
modelling
act of creating a model (3.15), i.e. act of creating a representation of a system
3.17
simulation
imitation of the behavioural characteristics of a system, entity, phenomenon, or process
Note 1 to entry: The term “simulation” can be also used for the production of a computer (or physical) model
(3.15) of something, especially the purpose of study.
3.18
space debris
objects of human origin in Earth orbit or re-entering the atmosphere, including fragments and elements
thereof, that no longer serve a useful purpose
[SOURCE: ISO 24113:2019, 3.23, modified — The deprecated term and note 1 to entry have been
removed.]
3.19
dependability
ability to perform as and when required
Note 1 to entry: Its main components are reliability, availability and maintainability (3.11).
Note 2 to entry: The extent to which the fulfilment of a required function can be justifiably trusted.
Note 3 to entry: Dependability shall be considered in conjunction with safety.
Note 4 to entry: Dependability is used as a collective term for the time-related quality characteristics of an item.
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ISO 23835:2022(E)
[SOURCE: IEC 60050-192:2015, 192-01-22, modified — The original note 1 to entry has been replaced
by Notes 1 to 3 to entry.]
3.20
electromagnetic compatibility
EMC
ability of a space equipment or system to function satisfactorily in its electromagnetic environment
without introducing intolerable electromagnetic disturbances to anything in that environment
[SOURCE: ISO 14302:2002, 3.1.4]
4 Fundamental requirements
4.1 System performance
The mechanism functional performance shall conform to the system performance requirements
allocated to the mechanism.
4.2 Mission
Design of the mechanism shall meet the requirements applied throughout the entire period of the
mission specified in individual programs. Design of the mechanism shall meet all requirements and
encountered environmental conditions in each phase of the mission.
4.3 Function
a) The kinematic requirements applicable to each position change shall be specified.
NOTE 1 For example, position over time, velocity and acceleration.
b) Mechanical interface, position accuracy or velocity tolerances shall be specified and verified that
they meet the functional needs.
NOTE 2 Mechanical interfaces include assembly and test rigging and other installation and integration
conditions.
c) The envelope of movement for each moving part shall be defined.
d) It shall be ensured that there is no mechanical interference between the movement of each part
with any other part of the mechanism, the spacecraft, the payload or the launch vehicle.
5 Design requirements
5.1 Interfaces
a) Structural interfaces
Mechanisms shall conform to the structural interface conditions and requirements defined in the
specification.
b) Thermal interfaces
Mechanisms shall conform to the thermal interface conditions and requirements defined in the
specification.
c) Thermo-mechanical interfaces
Mechanisms shall be designed in consideration of thermal stress induced between the mechanism
and its installation points.
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ISO 23835:2022(E)
d) Electrical interfaces
Mechanisms shall conform to the electrical interface conditions and requirements defined in the
specification.
e) Physical interfaces
The mass of a mechanism shall conform to the requirements defined in the specification.
f) Other interfaces
Mechanisms shall conform to the interface conditions of optical (visual field), mounting alignment,
accessibility during operation, envelope area, clearance with other equipment and ground-based
equipment defined in the specification.
5.2 Environmental design
5.2.1 General
Mechanisms shall conform to the environmental condition requirements defined in the specification.
5.2.2 Ground environment
a) Mechanisms shall meet the required performance even under ground handling environment
conditions such as ground test, assembly, storage and transportation.
b) Mechanisms shall be designed to take into account the ground test environment including
temperature, vibration, sound, shock, different atmospheric gases, pressure, humidity, cleanness
and corrosive environment.
5.2.3 Launch vehicle flight environment
a) Mechanisms shall meet the required performance after being exposed to launch vehicle flight
environment conditions.
b) As to the launching environment, mechanisms shall be designed to take into account changes in the
parameters such as temperature, vibration, sound, shock, pressure and humidity.
5.2.4 Orbital environment
a) Mechanisms shall meet the required performance under orbital environment conditions until the
end of their required operating life is reached.
b) As to the orbital environment, mechanisms shall be designed to take into account environmental
factors such as vacuum, temperature cycle, vibration, shock, radiation, ultraviolet and atomic
oxygen. Mechanisms shall be designed to take into account the environmental effects in outer
space on the materials used in the mechanism.
5.3 Parts and materials
5.3.1 General
The parts, materials and processes of the mechanism shall be selected to meet the requirements about
function, performance, environmental conditions, quality, reliability, and other properties s
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