ISO/TS 6434:2024

Technical
Specification
ISO/TS 6434
First edition
Space systems — Design, testing and
2024-01
operation of a large constellation of
spacecraft
Systèmes spatiaux — Conception, essais et manœuvre d’une
grande constellation d'engins spatiaux
Reference number
© ISO 2024
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ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative reference . 1
3 Terms and definitions . 1
4 Abbreviated terms . 2
5 Requirements . 2
5.1 Mission design.2
5.1.1 Orbit selection of constellation and maintenance to minimise collision risk .2
5.1.2 Intra-constellation collision avoidance .2
5.1.3 Space debris mitigation .3
5.1.4 Selection of launch service providers .3
5.1.5 Assessment on the long-term evolution of debris environment .3
5.2 Spacecraft design .3
5.2.1 Reliability design .3
5.2.2 Design to support collision avoidance .5
5.2.3 Space debris mitigation design .5
5.2.4 Design to support successful disposal .5
5.2.5 Safe re-entry .5
5.2.6 Large constellation radio frequency interference mitigation.5
5.2.7 Large constellation minimization of disruptive visual brightness .6
5.3 Qualification and testing .6
5.3.1 Verification and validation based upon established standards and procedures .6
5.3.2 Test and checkout before to injecting into the planned orbit .6
5.4 Operations and collision avoidance .6
5.4.1 Quality and reliability control during operation .6
5.4.2 Conjunction assessment and collision avoidance.7
5.4.3 Large constellation Radio frequency interference mitigating operation .8
5.4.4 Large constellation operation to minimise disruptive visual brightness .8
5.5 Disposal of spacecraft .8
5.5.1 Post-mission disposal .8
5.5.2 Criteria for initiating disposal .8
5.5.3 Determination of mission extension or termination .8
5.5.4 Disposal upon decommissioning .8
5.5.5 Spacecraft passivation .9
5.5.6 Active debris removal in operations.9
Bibliography .10

iii
Foreword
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iv
Introduction
More than a dozen large constellations of spacecraft are planned to be launched in the next several years.
While large constellations can provide societal benefits to humanity, they can also put pressure on the orbital
and electro-magnetic environments, introducing mission design, hardware design, launch, operations and
disposal challenges to other operating space assets and the long-term sustainability of space activities.
This document provides a set of standard practices throughout the large constellation life cycle to promote
safety on the ground from re-entry hazard and long-term sustainability of space operations.
In developing this document, the practices of the existing large constellation programs, consensus in the
[1]
Space Safety Coalition, “Best Practices for the Sustainability of Space Operations,” , the “Statement on
[2]
Large Constellations” of the “Inter-Agency Space Debris Coordination Committee (IADC)”, ISO 24113,
which specifies space debris mitigation requirements, the “Guidelines for the Long-term Sustainability of
[3]
Outer Space Activities” COPUOOS June 2021 and other effective documents were consulted.

v
Technical Specification ISO/TS 6434:2024(en)
Space systems — Design, testing and operation of a large
constellation of spacecraft
1 Scope
This document provides requirements that are either unique or particularly relevant to large constellations
of spacecraft operating in the LEO protected region throughout their life cycle, including planning, designing,
testing, operating and disposal activities.
The requirements in this document are applicable to large constellation owners. While some are directly
applicable to the constellation owners, others are allocated to the manufactures or operators under the
responsibility of the constellation owners.
2 Normative reference
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.
1)
ISO 19389 , Space data and information transfer systems — Conjunction data message
ISO 24113, Space systems — Space debris mitigation requirements
2)
ISO 26900 , Space data and information transfer systems — Orbit data messages
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
large constellation of spacecraft
large constellation
system of a hundred or more spacecraft working together
Note 1 to entry: While providing a specific quantity of spacecraft, the size, mass, complexity and function of the
spacecraft also have a bearing.
3.2
latitude range
band of geocentric latitude that spacecraft in two constellations may simultaneously occupy
3.3
radial separation
distance between constellation orbits in the radial direction within a common latitude range (3.2),
irrespective of right ascension of ascending node and timing (nodal regression and in-track motion)
1) Adoption from CCSDS 508.0-B-1.
2) Adoption from CCSDS 502.0-B-2.

4 Abbreviated terms
CCSDS Consultative Committee for Space Data System
DoA dead-on-arrival
ITU International Telecommunication Union
LED light emitting diode
LEO low Earth orbit
RCS reaction control system
RFI radio frequency interference
SSA space situational awareness
5 Requirements
5.1 Mission design
5.1.1 Orbit selection of constellation and maintenance to minimise collision risk
5.1.1.1 Selection of orbit of constellation considering collision risk
The orbit of constellation shall be selected to minimise the probability of collision with other space objects.
5.1.1.2 Selection of orbit of constellation considering collision risk with neighbouring
constellations
The constellations shall be designed and operated to avoid interaction with neighbouring large constellations
to assure safe operations under both nominal and anomalous vehicle operating conditions.
NOTE Maintaining an adequate radial separation from other large constellations is an effective way to minimize
collision risk.
5.1.2 Intra-constellation collision avoidance
5.1.2.1 Allocation of orbit of member spacecraft to minimise collision risk
Constellations shall be configured to mitigate collision risk between constellation spacecraft according to
the threshold defined by approving agent.
5.1.2.2 Allocation of orbit considering the contingencies
Constellations shall be configured such that constituent failures do not significantly elevate intra-
constellation collision risk (e.g. by separating the orbit planes and radial profiles to avoid intersection
points).
5.1.2.3 Orbit control of spacecraft during operation
Spacecraft insertion, operational and disposal orbits shall be chosen considering collision risk and post-
mission orbital lifetime, commensurate with mission objectives and constraints.

5.1.3 Space debris mitigation
A large constellation shall satisfy the space debris mitigation requirements in ISO 24113, except where
stricter versions of the requirements are specified elsewhere in this document.
5.1.4 Selection of launch service providers
The launch service provider shall be selected from those that conform to the space debris mitigation
requirements in ISO 24113.
5.1.5 Assessment on the long-term evolution of debris environment
When planning to apply a large constellation, an assessment of the aggregate risk to space operations
sustainability posed by the mission and constellation design, the individual spacecraft design, operations,
and launch services shall be made and approved by the responsible authority.
NOTE 1 Commonly used metrics include risks placed on other operators, expected levels of space debris, likelihood
of triggering a Kessler syndrome, etc.
NOTE 2 Such a risk assessment can identify increased levels for post-mission success rate and/or reduced disposal
lifetime as described in 5.2 for constellation members and associated launch services.
5.2 Spacecraft design
5.2.1 Reliability design
5.2.1.1 General
Large constellation spacecraft designs shall safeguard against deployment of DoA spacecraft, unintentional
termination of operation, accidental break-ups including due to collision, failure to conduct proper disposal
actions conforming to requirements in 5.2.
NOTE 1 For details of a rigorous qualification and testing program, see 5.3, which mentions that all relevant
components are examined in the testing program given the mass production of constellation spacecraft.
NOTE 2 For details for the collision avoidance, see 5.4.2.
NOTE 3 For information on a proper disposal, see 5.5.
5.2.1.2 Availability of components and materials that have a limit for useful life
5.2.1.2.1 General
Any components and materials whose useful life (including “operation life” and “storage life”) is limited
shall be designed or selected to assure the design life. If the operation is expected to be extended beyond the
design life, they shall satisfy the planned extended life.
5.2.1.2.2 Operation time limited items
For components essential for the disposal function which have limited operation time or cycles and whose
remaining usable service life is uncertain, an operations log shall be developed and procedurally maintained
to enable analysts to assess the component’s residual life to ensure successful post-mission disposal prior to
component failure.
5.2.1.2.3 Storage life limited items
If the mission’s operational period is extended, the total operation period shall not exceed the “storage life”
of any components used for disposal.

5.2.1.3 Critical components in new flight application
All components that are essential for the disposal function (including those required for maintaining
spacecraft control and performing active collision avoidance and de-orbiting) shall have either been
demonstrated on-orbit, or pass a rigorous testing regimen as specified in 5.3.2.
5.2.1.4 Design for post-mission orbital lifetime
a) Besides the
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