ISO 14302:2022

Space systems - Electromagnetic compatibility requirements

This document contains a process to establish performance requirements for the purpose of ensuring space systems electromagnetic compatibility (EMC). The engineering issues to be addressed in order to achieve system-level EMC are identified herein, with guidance and rationale towards achieving specification conformance. The method for the derivation of typical equipment-level requirements from a space-system-level requirement is illustrated. This document also aids in the selection of tailored requirements for a specific mission (see Annex A).

Systèmes spatiaux — Exigences relatives à la compatibilité électromagnétique

General Information

• Status: Published
• Publication Date: 14-Jun-2022
• ICS: 33.100.01 - Electromagnetic compatibility in general
• 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 1 - Design engineering and production
• Current Stage: 6060 - International Standard published
• Start Date: 15-Jun-2022
• Due Date: 07-Dec-2021
• Completion Date: 15-Jun-2022

Relations

• Revises: ISO 14302:2002 - Space systems - Electromagnetic compatibility requirements
• Effective Date: 23-Apr-2020

Overview

ISO 14302:2022 - Space systems - Electromagnetic compatibility requirements defines a process to establish system- and equipment-level electromagnetic compatibility (EMC) performance requirements for space systems. The second edition (2022) updates the original 2002 publication and provides engineering guidance, rationale (Annex A), and a method to derive typical equipment-level EMI requirements from system-level EMC requirements. The document supports tailoring of requirements for specific missions and references civilian EMI test methods to reduce cost and leverage standard test practice.

Key topics and technical requirements

• System-level EMC programme: Establishes an EMC control programme and timeline (flow chart) covering planning, design, analysis, test and evaluation phases.
• Equipment/subsystem criticality categories: Identifies criticality levels used to apply safety margins and verification rigor.
• External electromagnetic environment & intrasystem EMC: Guidance to characterize environmental threats and control interactions within the spacecraft.
• EMI control, grounding and wiring design, electrical bonding: Engineering considerations to limit conducted and radiated interference.
• Antenna-to-antenna (RF) compatibility: Requirements to prevent inter-antenna interference on multi-transmitter/receiver platforms.
• Hazards and special phenomena: Includes multipaction, passive intermodulation (PIM), electrostatic discharge (ESD), lightning, spacecraft charging, and life-cycle considerations.
• Power bus and signal cable requirements: Coverage of source- and load-induced power-bus conducted interference (time and frequency domain), switching transients, ripple, and signal-cable conducted interference.
• Equipment immunity and emissions: Immunity to radiated fields, magnetic field-induced signals, ESD, and control of antenna-port immunity/out-of-band interference.
• Verification and documentation: Defines verification deliverables such as the Electromagnetic Effects Verification Plan (EMEVP) and Electromagnetic Effects Verification Report (EMEVR), plus equipment-level testing guidance (no prescriptive test limits included).

Practical applications - who uses ISO 14302:2022

• Spacecraft systems engineers and EMC engineers use it to set and flow down EMC requirements across subsystems and equipment.
• Design and test teams leverage the guidance for grounding, wiring, bonding, EMI control and selection of test methods.
• Program managers and procurement specialists use the standard to specify EMC requirements and acceptance/verification artifacts (EMEVP/EMEVR).
• Test laboratories and contractors apply the document to prepare test plans and to derive equipment-level tests from system-level needs.
• Standards harmonization: Useful when aligning project requirements with AIAA, ECSS, MIL‑STD and other aerospace EMC practices.

Related standards

ISO 14302:2022 aligns and references contemporary civilian and aerospace EMC work (AIAA, ECSS, MIL‑STD) and is intended to be tailored to mission-specific contractual needs. Annex A provides the rationale underpinning requirements and chosen test techniques.

Keywords: ISO 14302:2022, electromagnetic compatibility, EMC, space systems, EMI testing, multipaction, electrostatic discharge, antenna compatibility, power bus interference, grounding and bonding.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 14302
Second edition
2022-06
Space systems — Electromagnetic
compatibility requirements
Systèmes spatiaux — Exigences relatives à la compatibilité
électromagnétique
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
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
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, definitions and abbreviated terms . 1
3.1 Terms and definitions . 1
3.2 Abbreviated terms . 3
4 Requirements . 5
4.1 General system requirements . 5
4.1.1 General . 5
4.1.2 System-level EMC programme . 5
4.1.3 Equipment/subsystem criticality categories . 8
4.1.4 Safety margins . 8
4.2 Specific system requirements . . 8
4.2.1 External electromagnetic environment . 8
4.2.2 Intrasystem EMC . 8
4.2.3 EMI control . 8
4.2.4 Grounding and wiring design . 8
4.2.5 Electrical bonding . 9
4.2.6 Antenna-to-antenna (RF) compatibility . 10
4.2.7 Lightning . 10
4.2.8 Spacecraft and electrostatic charging . 10
4.2.9 Hazards of electromagnetic radiation .12
4.2.10 Life cycle considerations .12
4.2.11 External grounds .12
4.2.12 Spacecraft d.c. magnetic emissions .12
4.2.13 Electric propulsion systems .12
4.3 Equipment-level EMI requirements . 13
4.3.1 General .13
4.3.2 Power bus conducted interference, time and frequency domain, source
induced .13
4.3.3 Power bus conducted interference, load induced, frequency domain .13
4.3.4 Power bus load-induced switching transient emissions. 14
4.3.5 Power bus load-induced time domain ripple. 15
4.3.6 Signal cable conducted interference, frequency domain . .15
4.3.7 Antenna connection port spurious emissions . 15
4.3.8 Magnetic field radiated emissions . 15
4.3.9 Radiated electric field emissions . 15
4.3.10 Immunity to audio frequency power-line ripple . 15
4.3.11 Immunity to power-line switching transients . 15
4.3.12 Immunity to the conducted effects of radiated electromagnetic fields . 16
4.3.13 Immunity to audio frequency radiated magnetic fields . 16
4.3.14 Immunity to radiated electromagnetic fields . 16
4.3.15 Immunity to magnetic fields induced signals to cabling . 16
4.3.16 Control of antenna port immunity to out-of-band interference . 16
4.3.17 Immunity to electrostatic discharge . 16
4.3.18 Passive Intermodulation (PIM) . 16
4.3.19 Multipaction . 16
5 Verification .16
5.1 General system requirements . 16
5.1.1 General . 16
5.1.2 System-level electromagnetic effects verification plan (EMEVP) . 17
iii
5.1.3 Electromagnetic effects verification report (EMEVR) . 17
5.1.4 Safety margin demonstration of critical/EED circuit . 17
5.2 Specific system requirements . . 18
5.2.1 External electromagnetic environment . 18
5.2.2 Intrasystem electromagnetic compatibility . 18
5.2.3 Electromagnetic interference control . 18
5.2.4 Grounding and wiring design . 18
5.2.5 Electrical bonding . 18
5.2.6 Antenna-to-antenna (RF) compatibility . 19
5.2.7 Lightning . 19
5.2.8 Spacecraft and static charging. 19
5.2.9 Hazards of electromagnetic radiation . 20
5.2.10 Life cycle . 20
5.2.11 External grounds .20
5.2.12 Spacecraft d.c. magnetic emissions . 20
5.3 Equipment-level EMI testing . 20
5.3.1 General .20
5.3.2 Power bus conducted interference, time and frequency domain, source
induced . 21
5.3.3 Power bus conducted interference, load induced, frequency domain . 21
5.3.4 Power bus load-induced switching transients . 21
5.3.5 Power bus load-induced time domain ripple. 21
5.3.6 Signal cable conducted interference, frequency domain . . 21
5.3.7 Antenna connection port spurious emissions .22
5.3.8 Magnetic field radiated emissions . 22
5.3.9 Radiated electric field emissions . 22
5.3.10 Immunity to audio frequency power-line ripple .22
5.3.11 Immunity to power-line switching transients .22
5.3.12 Immunity to the conducted effects of radiated electromagnetic fields .22
5.3.13 Immunity to audio frequency radiated magnetic fields .22
5.3.14 Immunity to radiated electromagnetic fields .22
5.3.15 Immunity to magnetic fields induced signals to cabling .22
5.3.16 Control of antenna port immunity to out-of-band interference .22
5.3.17 Immunity to electrostatic discharge . 22
Annex A (informative) Rationale behind requirements and tests .24
Bibliography .46
iv
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.
This second edition cancels and replaces the first edition (ISO 14302:2002), which has been technically
revised.
The main changes are as follows:
— updating related standard documents such as AIAA, ECSS, MIL-STD and etc., considering with
new work has been accomplished over the past 10 years in this field within the US AIAA and ECSS.
Particularly in space - there are many more orbiting transmitters and receivers exploiting the EM
spectrum for earth observation, communications etc.;
— the inclusion of EMC flow chart to clarify timeline for EMC plan, design, analysis and test/evaluation
phase of project;
— the inclusion of technical requirements for multipaction, intermodulation and electrostatic
discharge with consideration of changes of electronic equipment with higher speed digital devices,
data bus & clock frequencies, and switch mode Power supplies by PWM signalling;
— updating of technical requirements, taking into account that equipment is still being qualified or
qualified by similarity to heritage specifications from the 80's.
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
This document addresses the equipment-level requirements, verification and rationale of system-level
compatibility concerns used in the development and procurement of complete space systems.
This document includes requirements at all the following levels:
— general system requirements;
— specific system requirements;
— equipment-level electromagnetic interference requirements.
The equipment-level requirements are summarized in Tables 1 and 2.
This document does not include detailed design requirements. Instead, engineering issues to be
addressed during execution of the electromagnetic compatibility (EMC) control programme are
presented. Requirements in this document may be tailored based on contractual agreements.
This document references civilian equipment-level electromagnetic interference (EMI) test methods
to minimize cost and allow the use of standard test methods. This document does not contain EMI
test limits. Test limits should be developed based on the environment, power quality definition and
operational requirements.
Annex A presents the rationale behind each requirement/test technique, guidance for meeting
requirements and test procedures where an acceptable reference is not available. Use of Annex A is
advised in order to allow for optimal tailoring of this document for individual programmes.
vi
INTERNATIONAL STANDARD ISO 14302:2022(E)
Space systems — Electromagnetic compatibility
requirements
1 Scope
This document contains a process to establish performance requirements for the purpose of ensuring
space systems electromagnetic compatibility (EMC). The engineering issues to be addressed in order
to achieve system-level EMC are identified herein, with guidance and rationale towards achieving
specification conformance. The method for the derivation of typical equipment-level requirements from
a space-system-level requirement is illustrated. This document also aids in the selection of tailored
requirements for a specific mission (see Annex A).
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 7137:1995, Aircraft — Environmental conditions and test procedures for airborne equipment
IEC 61000-4-2, Electromagnetic compatibility (EMC) — Part 4-2: Testing and measurement techniques —
Electrostatic discharge immunity test
ISO 24637, Space systems — Electromagnetic interference (EMI) test reporting requirements
ECSS-E-20-01A, Multipaction Design and Test
Aerospace Report No. TOR-2014-02198, Standard/Handbook for Multipactor Breakdown Prevention in
Spacecraft Components
3 Terms, definitions and abbreviated terms
3.1 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/
3.1.1
break-out box
non-flight piece of test support equipment that is connected in-line with a cable that accommodates
external connection (usually binding posts) of instrumentation or series/parallel test networks to the
wiring in that cable
3.1.2
complete space system
suite of equipment, subsystems, skills, and techniques capable of performing or supporting an
operational role
Note 1 to entry: A complete space system includes related facilities, equipment, subsystems, materials, services,
and personnel required for its operation to the degree that it can be considered self-sufficient within its
operational or support environment.
Note 2 to entry: The complete space system normally refers to the spacecraft or launch vehicle itself.
3.1.3
dead-facing
removal of power from a circuit prior to mating/de-mating of the circuit interface (usually to prevent
arcing or inadvertent short circuits)
3.1.4
electromagnetic compatibility
EMC
ability of a space equipment or system to function satisfactorily in its intended electromagnetic
environment without introducing intolerable electromagnetic disturbances to anything in that
environment
3.1.5
electromagnetic interference
EMI
degradation of the performance of a space equipment (3.1.6), transmission, channel, or system caused
by an electromagnetic disturbance
3.1.6
equipment
integrated set of parts, and components
Note 1 to entry: An equipment accomplishes a specific function.
Note 2 to entry: An equipment is self-contained and classified as such for the purposes of separate manufacture,
procurement, drawings, specification, storage, issue, maintenance, or use.
SOURCE: ISO 10795 3.93
3.1.7
faying surface
prepared conductive surface of sufficient area and conductivity that, when joined under pressure
contact, ensures a low electrical bond impedance for the required life of the connection
3.1.8
floating
status of a circuit isolated from another one, which is characterized by a resistance of strong value in
parallel with a capacity.
Note 1 to entry: In low frequency, the circuit is actually high impedance; it is not the case in HF considering the
parasitic capacitor. “Floating” is therefore to use for a frequency domain that it is then necessary to specify.
3.1.9
immunity
ability of a device, equipment (3.1.6), or system to perform without degradation in the presence of an
electromagnetic disturbance
3.1.10
internal charging
phenomenon caused by penetration of high-energy electrons through spacecraft structures and/
or component walls so that these particles are incident on ungrounded metallic or dielectric internal
surfaces
3.1.11
line impedance stabilization network
LISN
network inserted in the supply mains lead of an apparatus to be tested which provides, in a given
frequency range, specified source or load impedance for the measurement of disturbance currents and
voltages and which may isolate the apparatus from the supply mains in that frequency range
3.1.12
power quality requirement
requirement developed for the space system that defines the conducted voltage and current noise (from
load regulation, spikes, sags, etc.) the power user can expect
3.1.13
procuring authority
agency or organization funding or administering a contract for the development of the space system
3.1.14
radio frequency interference
RFI
degradation of the reception of a wanted signal caused by a radio frequency disturbance
3.1.15
safety margin
ratio of circuit threshold of susceptibility (3.1.18) to induced circuit noise under worse-case expected
environmental conditions (intrasystem and intersystem)
3.1.16
subsystem
set of interdependent elements constituted to achieve a given objective by performing a specified
function, but that does not, on its own, satisfy the customer's requirement
Note 1 to entry: Generally, a piece of equipment is housed within a single enclosure, while a subsystem may
consist of several interconnected units.
Note 2 to entry: ISO 10795 3.231, modified — Note 1 to entry added.
3.1.17
susceptibility
correct operation of electrical equipment (3.1.6), referred to as the victim, in the presence of unplanned
electromagnetic disturbances
Note 1 to entry: A victim is a component/subsystem that is susceptible to interference.
3.1.18
suppression
act of eliminating electromagnetic noise through the process of filtering, shielding, or other methods
that reduce the impact of noise on a system
3.2 Abbreviated terms
ACS attitude control system
BCI bulk current injection
CDR critical design review
CE conducted emissions
CISPR International Special Committee on Radio Interference
COTS commercial off-the-shelf
CS conducted susceptibility
DSO digital storage oscilloscope
EED electro-explosive device
EGSE electrical ground support equipment
EMCAB electromagnetic compatibility advisory board
EME electromagnetic environment
EMEVP electromagnetic effects verification plan
EMEVR electromagnetic effects verification report
EMISM electromagnetic interference safety margin
ESD electrostatic discharge
EUT equipment under test
FMEA failure mode effects analysis
GEO geosynchronous Earth orbit
HF high frequency
ICD interface control document
LEO low Earth orbit
Mil-Std military standard
NASA National Aeronautics and Space Administration
PDR preliminary design review
RDR requirements definition review
RE radiated emissions
RF radio frequency
RFP request for proposal
r.m.s. root-mean-square
RS radiated susceptibility
r.s.s. root-sum-square
SAE Society of Automotive Engineers
SMPS switched mode power supply
TTL transistor-to-transistor logic
UHF ultrahigh frequency
VHF very high frequency
VLF very low frequency
4 Requirements
4.1 General system requirements
4.1.1 General
The space system shall be electromagnetically compatible among all equipment/subsystems within the
space system and with the self-induced and defined external electromagnetic environment during all
phases of its mission.
4.1.2 System-level EMC programme
4.1.2.1 General
The procuring authority and prime contractor shall establish an overall EMC programme based
on requirements of this document, the statement of work, space system specification, and other
applicable contractual documents. The purpose of the EMC programme is to ensure space-system-
level compatibility with minimum impact to programme, cost, schedule, and operational capabilities.
An EMC programme shall include EMC control documentation and an EMC advisory board (EMCAB).
The EMC staff responsible for these functions should be appropriate to the size and complexity of
the programme. Typical programme milestones and their corresponding EMC data/deliverables are
provided in Annex A (see Table A.1). Commercial space programmes having historically successful EMC
control and management programmes in place may submit documentation to the procuring authority
for an alternate means of equipment-level conformance, providing that the system-level interface
requirements of this document are met.
When viewed from the perspective of a specific program or project context, the requirements defined
in this document may be tailored to match the actual requirements of the particular program or
project. Tailoring of requirements shall be undertaken in consultation with the procuring agency where
applicable.
NOTE Tailoring is a process by which individual requirements or specifications, standards, and related
documents are evaluated and made applicable to a specific program or project by selection, and in some
exceptional cases, modification and addition of requirements in the standards.
4.1.2.2 Electromagnetic compatibility advisory board
The EMCAB shall be responsible for timely and effective execution of the EMC programme under the
general project manager. The prime contractor or developer shall chair the EMCAB, with procuring
authority oversight. Other EMCAB members may invite associate contractors or developers and an
independent expert of a space engineering certification body. Procuring activities may waive this
requirement for systems that do not involve sufficient levels of integration to justify such a board;
then the prime contractor shall execute EMCAB functions. The EMCAB shall accomplish its duties and
document its activities mainly through the use of the system-level EMC documentation. It is also the
responsibility of the EMCAB to solve problems related to EMC as they arise.
4.1.2.3 EMC programme
Details of the EMC programme shall be documented in the EMC control plan or other EMC contract
documentation. Initial releases shall document the mechanics of the EMC programme, including
basic design guidelines, while subsequent routine updates shall document programme progress. The
requirements and approach established by the prime contractor shall be in a contractual document. An
overall programmatic EMC program is shown in Figure 1. The contents of the EMC control plan or other
EMC contract documentation shall include, but not be limited to, the following:
a) EMC programme management is defined by:
1) responsibilities of procuring authority, prime and associate contractors, lines and protocols of
communication, and control of design changes;
2) planning the EMC programme, consisting of:
i) facilities and personnel required for successful implementation of the EMC programme;
ii) methods and procedures of accomplishing EMC design reviews and coordination (within
the EMCAB, if applicable);
iii) proposed charter;
iv) details of the operation of the EMCAB, if needed;
3) programme schedules, including integration of the EMC programme schedule and milestones
within th e programme development master schedule;
b) system-level performance and design requirements, consisting of:
1) definition of electromagnetic and related environments; including considerations related to
hazards of electromagnetic radiation to fuels, humans, and explosive systems, such as electro-
explosive devices (EED's) (see 4.2.9), launch vehicles, interfacing vehicles, and launch site
environment, including electronic equipment at the launch site area;
2) definition of critical circuits;
c) electro-explosive devices, consisting of:
1) appropriate EED EMC requirements;
2) design techniques;
3) verification techniques;
d) subsystem/equipment EMI performance requirements and verification, consisting of:
1) allocation of design responses at system and subsystem/equipment levels as defined in this
document;
2) allocated EMI performance at the equipment level, including tailored equipment-level
requirement of which the control plan is the vehicle for tailoring limits and test methods;
3) test results from subsystem/equipment level EMI tests shall be summarized:
i) any specification non-conformances judged to be acceptable shall be described in detail;
and analysis of the non-compliant conditions on overall EMC performance shall be
provided as a part of the justifying rationale;
ii) cost, mass, schedule, reliability, system operability, and other factors should also be
addressed;
e) EMC analysis:
1) by making predictions of intrasystem EMI/EMC based on expected or actual equipment/
subsystem EMI characteristics;
2) by designing solutions for predicted or actual interference situations using equipment-level
data as input, impedance coupling (conducted emissions), wire-to-wire, field-to-wire:
i) all coupling modes should be considered to determine or predict EMI safety margin
(EMISM) of intra-system EMI/EMC based on specified interface control document
(ICD) values or actual (waiver/deviation request) values of equipment/subsystem EMI
characteristics;
ii) design solutions should address what filtering, shielding, and grounding need to be applied
to achieve these predicted EMISM's;
f) spacecraft charging/discharging analysis;
g) space-system-level EMC verification consisting of an outline of system-level EMC verification
plan, including rationale for selection of critical circuits for safety margin demonstration, and
instrumentation techniques for both critical and EED circuit and sensitization;
h) method of disposing waivers initial release and subsequent updates of the EMC control plan shall
be prepared and submitted in accordance with contractual terms.
i)
Figure 1 — Overall programmatic EMC program
4.1.3 Equipment/subsystem criticality categories
The EMCAB shall identify functional criticality for all equipment/subsystems. Functional criticality
categories include the following:
a) category I, safety critical:
EMI problems can result in loss of life and/or loss of space platform;
b) category II, mission critical:
EMI problems can result in injury, damage to space platform, mission abort or delay, or performance
degradation which unacceptably reduces mission effectiveness;
c) category III, non-critical:
EMI problems can result only in annoyance, minor discomfort, or loss of performance which does
not reduce desired spacecraft effectiveness.
4.1.4 Safety margins
Design safety margins shall be established by the EMCAB for both critical functions and EED circuits.
Design margins shall consider likely degradation modes of circuits and circuit protection methods over
projected spacecraft lifetime.
4.2 Specific system requirements
4.2.1 External electromagnetic environment
The space system shall operate without performance degradation in the electromagnetic environment,
not only self-induced but that due to external sources (intersystem EMI) such as other radio frequency
sources, high-energy charged particles of space environment or plasma effects. The EMCAB shall
determine the electromagnetic environment based on mission requirements.
4.2.2 Intrasystem EMC
The space system shall not interfere with key requirements of a subsystem. Each equipment/subsystem
shall operate without performance degradation during concurrent operation of any combination of the
remaining equipment/subsystems, subject to mission requirements.
4.2.3 EMI control
The prime contractor shall be responsible for translating system-level EMC goals into equipment/
subsystem-level EMI performance requirements. Test limits and test methods may be tailored
if required, with procuring authority approval, to meet programme needs. EMI characteristics
(emissions and susceptibility) shall be controlled to the extent necessary to ensure intrasystem EMC
and compatibility with the predicted external electromagnetic environment. Equipment/subsystem-
level EMI performance requirements and test methods shall be in accordance with 4.3 and 5.3.
4.2.4 Grounding and wiring design
4.2.4.1 Grounding
A controlled ground reference concept shall be established for the space system prior to initial release
of the EMC control plan or other EMC contract documentation. Both power and signal returns and
references shall be considered. Impedance magnitudes of these connections over the affected signal
spectrum shall be considered in determining which kinds of power and signals may share common
paths (wire or structure). Resistance and inductance values for each element of the ground return
circuit architecture may be assigned; the common-mode voltages that develop at circuit reference
points can then be computed. These computed values may be compared to conducted susceptibility
requirements for equipment.
For one architecture assumption, and knowing the noisy signals and EM environments, the computation
of the reported energies from sources to receivers should be performed at the system scale. The
architecture definition includes materials nature, grounding choices and harnesses locations. Then the
EMC objectives can be defined with the margins for all equipment under sources of the same level that
the ones considered with their shields in the computation.
4.2.4.2 Wiring
Wiring, cable separation, shielding, and signal category design guidelines for the space system shall be
established. Pigtail shield connections shall not be used.
4.2.5 Electrical bonding
4.2.5.1 General
Electrical bonding measures shall be implemented for management of intentional electrical current
paths and control of voltage potentials to ensure required space system performance and protection
of personnel. Bonding provisions shall be compatible with other requirements imposed on the space
system for corrosion control.
4.2.5.2 Power current feeder and return paths
If the structure is used as the current return path, bonding provisions shall be provided so that current
paths of electrical power sources are such that the total direct current (d.c.) voltage drops between
the power subsystem point of regulation and the electrical loads are within applicable power quality
standard tolerances.
4.2.5.3 Shock and safety hazard
To prevent shock hazards to personnel, all exposed conductive items subject to fault condition charging
shall be bonded as necessary to limit potentials to prevent shock to personnel. In order to clear faults
or provide against accidental discharge of fault current to ground through a conductor, all exposed
conductive items, which can become charged due to an electrical fault condition, shall be bonded to the
ground subsystem. Bonding impedance shall be sufficiently low to ensure enough current to clear the
fault by tripping a circuit protection device.
4.2.5.4 Antenna counterpoise
Antenna structures relying on a counterpoise connected to (or implemented on) the spacecraft skin
shall have an RF bond to structure such that RF currents flowing on the skin have a low impedance
path to and through the counterpoise.
4.2.5.5 RF potentials
All electronic and electrical items, which can experience degraded operation or can degrade the
operation of other electronic or electrical items in response to external electromagnetic energy, shall
be bonded to the ground subsystem with a faying surface bond to present a low impedance at the
frequencies of interest. For composite materials, bonding shall be alternating current (a.c.) accomplished
at impedance levels consistent with the materials in use. Where vibration or thermal isolation is
required, bond straps may be used. The bond straps shall be as short as possible and maintain a low
inductance path. Bond straps should only be used as a last resort.
4.2.5.6 Electrostatic discharge
Any isolated conducting items larger than 3 cm shall be bonded to the ground subsystem in order to
avoid a differential build-up of charge that would result in an electrostatic discharge, unless it is shown
that there would not be enough charge build-up to cause a hazard. Refer to NASA-HDBK-4002A dated
03-03-2011 for further guidance.
4.2.5.7 Explosive atmosphere protection
Conducting elements in the vicinity of explosive and flammable materials shall be bonded to the
ground subsystem such that arcing or heat rise due to fault currents or lightning currents (either
directly applied or induced) is insufficient to cause ignition of the flammable substance. In space
plasma environments, fault currents may occur across pins of separated (exposed pins) connectors.
Dead-facing shall be employed before demating connectors in an explosive atmosphere and in a plasma
environment of thrusters.
4.2.6 Antenna-to-antenna (RF) compatibility
The space system shall exhibit RF compatibility among all antenna-connected equipment/
subsystems. This requirement is also applicable on an intersystem basis when there is a required
intersystem interface. The RF compatibility analysis, if used in lieu of a test, shall include the effects of
intermodulation products.
4.2.7 Lightning
The space system shall be protected against both direct and indirect effects of lightning such that
the mission can be completed without degradation of performance after exposure to the lightning
environment. Use test procedure ISO 7137:1995, 3.8 (Section 22) for demonstrating compatibility with
the lightning indirect-effects environment and test procedure ISO 7137:1995, 3.10 (Section 23) for the
direct-effects environment. Protection may be a combination of operational avoidance of the lightning
environment and electrical overstress design techniques.
4.2.8 Spacecraft and electrostatic charging
4.2.8.1 General
The space system shall control and dissipate build-up of electrostatic charges both from prelaunch
ground sources and from on-orbit energetic plasma environments and effects of high-energy charged
particles to the extent necessary to protect against personnel shock hazard, fuel ignition hazard, radio
frequency interference (RFI), and destruction of dielectric materials and electronic components due to
static discharge.
4.2.8.2 Plasma-generated/payload-induced differential charging/discharges
Plasma-induced differential charging, occurrence of electrical discharges and degrading effects upon
the space system nominal performances shall be minimized to prevent such occurrences by design and
integration precautions. Because the elimination of all discharges cannot be guaranteed, the full system
shall be hardened and verified so that no malfunctions, degradation of performances, or deviation
from identified parameters beyond tolerances given by corresponding specifications occur when the
spacecraft is exposed to repetitive electrostatic arc-discharges representative of expected transient
phenomena.
4.2.8.3 Internal charging
If the orbit parameters are such that the incident electron flux is high enough to cause internal charging,
hardening techniques shall be applied to minimize the charging of these surfaces, preventing them
from reaching the electrostatic discharge (ESD) discharging threshold.
4.2.8.4 Charging of fluid lines
All pipes, tubes, and hoses that carry fluids
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