ISO 21740:2025
(Main)Space systems — Launch window estimation and collision avoidance
Space systems — Launch window estimation and collision avoidance
This document establishes the general safety launch collision avoidance (safety LCOLA) requirements for the avoidance of collision between the collection of newly launched objects resulting from a space launch [including launch vehicle stage(s) and payloads or released objects] and human-inhabited or human-habitable space stations and space vehicles. The document specifies the requirements for the analysis of launch times and procedures for identifying safe launch opportunities. It also describes the assessment and constraints for collision avoidance risk evaluation metrics (launch collision probability and standoff distance).
Systèmes spatiaux — Estimation de la fenêtre de lancement et évitement des collisions
General Information
Buy Standard
Standards Content (Sample)
International
Standard
ISO 21740
First edition
Space systems — Launch window
2025-07
estimation and collision avoidance
Systèmes spatiaux — Estimation de la fenêtre de lancement et
évitement des collisions
Reference number
© ISO 2025
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: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative reference . 1
3 Terms and definitions . 1
4 Abbreviated terms . 3
5 Safety LCOLA requirements . 3
5.1 Conduct of a safety LCOLA .3
5.1.1 General .3
5.1.2 Launch vehicle stage(s) and deployed object(s) trajectories .4
5.1.3 Inhabitable vehicle ephemerides .4
5.2 Close encounter check for a safety LCOLA .4
5.3 Safety LCOLA launch hold criteria .5
5.4 Safety LCOLA screening timespan .5
5.5 LCOLA analysis run timing sequence .6
5.6 LCOLA standoff threshold .6
5.7 LCOLA standoff minimum threshold .6
6 LCOLA product . 7
Annex A (informative) LCOLA analysis challenges and methodologies . 8
Annex B (informative) Mission assurance LCOLA assessment .15
Annex C (informative) LCOLA survey . 17
Bibliography .20
iii
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 document 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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
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.
iv
Introduction
0.1 Overview
Human-inhabited and inhabitable space stations and space capsules are exposed to the risk of collision with
new launch vehicle stage(s) and spacecraft during their launch and early orbit phase. While such collision
threats also exist during on-orbit spacecraft operations, the launch and early orbit phase is unique in that
potential collisions with inhabitable space stations and space capsules can be avoided at minimal cost (i.e.
without the expenditure of on-orbit manoeuvring fuel) through the proper selection of suitable launch times.
[1]
Consistent with Clause B.5 of the United Nations Long Term Sustainability guidelines and to protect human
missions from the danger of collision with newly launched objects, the LCOLA approving agent may apply
launch collision avoidance (LCOLA) methods to assess either collision risk, close approach, or both. If this
assessment determines that launch at certain times would incur unacceptable risk to the human missions,
the LCOLA approving agent may delay the time of launch.
In addition to establishing requirements for the safety LCOLA process, Annex A provides details on
algorithms, processes, and screening criteria that may be used to conduct safety LCOLA assessments.
Annex A is intended to ensure the safety and integrity of human-inhabited or inhabitable space stations.
Annex B provides additional details on algorithms, processes, and screening criteria that may be used to
conduct mission assurance LCOLA assessments. Annex B is intended to ensure the safety and integrity of
both the newly launched space objects and any on-orbit active spacecraft that can potentially collide with
the launched objects for the initial LCOLA screening time period, and also to reduce the risk of unintended
fragmentation events caused by collision of the newly launched space objects with orbital debris during that
same initial screening period. A selection of general procedures for the determination of unacceptable risk
that result in the identification of all collision-safe launch opportunities is described.
0.2 Breakdown of space safety constituents across ISO standards
The space flight safety-relevant topics of space traffic coordination (STC), on-orbit collision avoidance, and
launch collision avoidance are closely related. To minimize duplication and maximize document consistency,
the various content that serve as the basis for these three disciplines has been divided up as shown in
Figure 1.
NOTE ISO 9490 and ISO 23705 are under development.
Figure 1 — Division of space safety operations content spanning several ISO standards
v
International Standard ISO 21740:2025(en)
Space systems — Launch window estimation and collision
avoidance
1 Scope
This document establishes the general safety launch collision avoidance (safety LCOLA) requirements for
the avoidance of collision between the collection of newly launched objects resulting from a space launch
[including launch vehicle stage(s) and payloads or released objects] and human-inhabited or human-
habitable space stations and space vehicles.
The document specifies the requirements for the analysis of launch times and procedures for identifying
safe launch opportunities. It also describes the assessment and constraints for collision avoidance risk
evaluation metrics (launch collision probability and standoff distance).
2 Normative reference
There are no normative references in this document.
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
conjunction
event where the positional separation between two objects is at a local minimum and that minimum is either
closer than a specified minimum distance threshold, or the estimated probability of collision at this local
minimum exceeds a specified launch collision probability (3.5) threshold
3.2
integrated LCOLA
integrated launch collision avoidance
composite launch window (3.9) stemming from the combination of safety LCOLA (3.15) and mission assurance
LCOLA (3.13) analyses
3.3
miss distance
minimum approach distance between a launching body and an orbiting body at their closest approach point
3.4
launch collision avoidance
LCOLA
process of mitigating the risk of collision between the newly launched objects resulting from a space launch
and any space objects in their paths
3.5
launch collision probability
quantification of the likelihood that a newly launched object would impact a designated space object during
a conjunction (3.1)
Note 1 to entry: Guidance, winds aloft, performance, estimated orbit propagation accuracy, and conjunction approach
geometry are examples of pre-launch launch vehicle (3.7) system errors.
3.6
launch period
selected range of dates when a launch is planned
3.7
launch vehicle
integrated system that is designed to carry payloads into and beyond its gravitational attracting body’s
atmosphere
Note 1 to entry: Such systems are typically composed of multiple stages.
3.8
launch vehicle stage
launch vehicle (3.7) component that has achieved flight above 150 km
3.9
launch window
range(s) of times on a day within the launch period (3.6) which adhere to all launch vehicle (3.7), payload, and
mission constraints, and during which the launch range is available and payloads and the launch vehicle are
ready for launch
3.10
launch window closure
portion of the launch window (3.9) which is unavailable (closed) due to a constraint violation
Note 1 to entry: Minimum LCOLA standoff distance (3.17) and launch collision probability (3.5) threshold are examples
of constraints.
3.11
launch window opportunity
portion of the launch window (3.9) which is available (open) because no launch range, launch vehicle (3.7),
payload or mission constraints are violated
3.12
LCOLA approving agent
entity who sets requirements for monitors and approves the procurement, management, oversight,
implementation, operations, performance evaluation, quality assurance and monitoring functions of the
LCOLA system under its authority
Note 1 to entry: The LCOLA approving agent’s responsibilities can be handled by a commercial, non-governmental,
governmental, or international individual or entity, as well as a mandated or delegated entity assigned by applicable
national regulati
...
FINAL DRAFT
International
Standard
ISO/FDIS 21740
ISO/TC 20/SC 14
Space systems — Launch window
Secretariat: ANSI
estimation and collision avoidance
Voting begins on:
2025-04-30
Voting terminates on:
2025-06-25
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
Reference number
ISO/FDIS 21740:2025(en) © ISO 2025
FINAL DRAFT
ISO/FDIS 21740:2025(en)
International
Standard
ISO/FDIS 21740
ISO/TC 20/SC 14
Space systems — Launch window
Secretariat: ANSI
estimation and collision avoidance
Voting begins on:
Voting terminates on:
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
© ISO 2025
IN ADDITION TO THEIR EVALUATION AS
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
or ISO’s member body in the country of the requester.
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland Reference number
ISO/FDIS 21740:2025(en) © ISO 2025
ii
ISO/FDIS 21740:2025(en)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative reference . 1
3 Terms and definitions . 1
4 Abbreviated terms . 3
5 Safety LCOLA requirements . 3
5.1 Conduct of a safety LCOLA .3
5.1.1 General .3
5.1.2 Launch vehicle stage(s) and deployed object(s) trajectories .3
5.1.3 Inhabitable vehicle ephemerides .4
5.2 Close encounter check for a safety LCOLA .4
5.3 Safety LCOLA launch hold criteria .5
5.4 Safety LCOLA screening timespan .5
5.5 LCOLA analysis run timing sequence .5
5.6 LCOLA standoff threshold .5
5.7 LCOLA standoff minimum threshold .6
6 LCOLA product . 6
Annex A (informative) LCOLA analysis challenges and methodologies . 7
Annex B (informative) Mission assurance LCOLA assessment . 14
Annex C (informative) LCOLA survey . 16
Bibliography . 19
iii
ISO/FDIS 21740:2025(en)
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 document 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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
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.
iv
ISO/FDIS 21740:2025(en)
Introduction
0.1 Overview
Human-inhabited and inhabitable space stations and space capsules are exposed to the risk of collision with
new launch vehicle stage(s) and spacecraft during their launch and early orbit phase. While such collision
threats also exist during on-orbit spacecraft operations, the launch and early orbit phase is unique in that
potential collisions with inhabitable space stations and space capsules can be avoided at minimal cost (i.e.
without the expenditure of on-orbit manoeuvring fuel) through the proper selection of suitable launch times.
[1]
Consistent with Clause B.5 of the United Nations Long Term Sustainability guidelines and to protect human
missions from the danger of collision with newly launched objects, the LCOLA approving agent may apply
launch collision avoidance (LCOLA) methods to assess either collision risk, close approach, or both. If this
assessment determines that launch at certain times would incur unacceptable risk to the human missions,
the LCOLA approving agent may delay the time of launch.
In addition to establishing requirements for the safety LCOLA process, Annex A provides details on
algorithms, processes, and screening criteria that may be used to conduct safety LCOLA assessments.
Annex A is intended to ensure the safety and integrity of human-inhabited or inhabitable space stations.
Annex B provides additional details on algorithms, processes, and screening criteria that may be used to
conduct mission assurance LCOLA assessments. Annex B is intended to ensure the safety and integrity of
both the newly launched space objects and any on-orbit active spacecraft that can potentially collide with
the launched objects for the initial LCOLA screening time period, and also to reduce the risk of unintended
fragmentation events caused by collision of the newly launched space objects with orbital debris during that
same initial screening period. A selection of general procedures for the determination of unacceptable risk
that result in the identification of all collision-safe launch opportunities is described.
0.2 Breakdown of space safety constituents across ISO standards
The space flight safety-relevant topics of space traffic coordination (STC), on-orbit collision avoidance, and
launch collision avoidance are closely related. To minimize duplication and maximize document consistency,
the various content that serve as the basis for these three disciplines has been divided up as shown in
Figure 1.
NOTE ISO 9490 and ISO 23705 are under development.
Figure 1 — Division of space safety operations content spanning several ISO standards
v
FINAL DRAFT International Standard ISO/FDIS 21740:2025(en)
Space systems — Launch window estimation and collision
avoidance
1 Scope
This document establishes the general safety launch collision avoidance (safety LCOLA) requirements for
the avoidance of collision between the collection of newly launched objects resulting from a space launch
[including launch vehicle stage(s) and payloads or released objects] and human-inhabited or human-
habitable space stations and space vehicles.
The document specifies the requirements for the analysis of launch times and procedures for identifying
safe launch opportunities. It also describes the assessment and constraints for collision avoidance risk
evaluation metrics (launch collision probability and standoff distance).
2 Normative reference
There are no normative references in this document.
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
conjunction
event where the positional separation between two objects is at a local minimum and that minimum is either
closer than a specified minimum distance threshold, or the estimated probability of collision at this local
minimum exceeds a specified launch collision probability (3.5) threshold
3.2
integrated LCOLA
integrated launch collision avoidance
composite launch window (3.9) stemming from the combination of safety LCOLA (3.15) and mission assurance
LCOLA (3.13) analyses
3.3
miss distance
minimum approach distance between a launching body and an orbiting body at their closest approach point
3.4
launch collision avoidance
LCOLA
process of mitigating the risk of collision between the newly launched objects resulting from a space launch
and any space objects in their paths
ISO/FDIS 21740:2025(en)
3.5
launch collision probability
quantification of the likelihood that a newly launched object would impact a designated space object during
a conjunction (3.1)
Note 1 to entry: Guidance, winds aloft, performance, estimated orbit propagation accuracy, and conjunction approach
geometry are examples of pre-launch launch vehicle (3.7) system errors.
3.6
launch period
selected range of dates when a launch is planned
3.7
launch vehicle
integrated system that is designed to carry payloads into and beyond its gravitational attracting body’s
atmosphere
Note 1 to entry: Such systems are typically composed of multiple stages.
3.8
launch vehicle stage
launch vehicle
...
ISO/FDIS 21740:2024(en)
ISO/TC 20/SC 14/WG 3
Secretariat: ANSI/AIAA
Date: 2025-01-3104-15
Space systems — Launch window estimation and collision avoidance
FDIS stage
ISO/FDIS 21740:2025(en)
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: + 41 22 749 01 11
EmailE-mail: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
ISO/FDIS 21740:20242025(en)
Contents
Foreword . iv
Introduction . v
1 Scope . 1
2 Normative reference . 1
3 Terms and definitions . 1
4 Abbreviated terms . 3
5 Safety LCOLA requirements . 3
5.1 Conduct of a safety LCOLA . 3
5.2 Close encounter check for a safety LCOLA . 4
5.3 Safety LCOLA launch hold criteria . 5
5.4 Safety LCOLA screening timespan . 6
5.5 LCOLA analysis run timing sequence . 6
5.6 LCOLA standoff threshold . 6
5.7 LCOLA standoff minimum threshold . 7
6 LCOLA product . 7
Annex A (informative) LCOLA analysis challenges and methodologies . 8
Annex B (informative) Mission assurance LCOLA assessment . 19
Annex C (informative) LCOLA survey . 22
Bibliography . 5
iii
ISO/FDIS 21740:2025(en)
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 documentsdocument 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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent rights
in respect thereof. As of the date of publication of this document, ISO had not received notice of (a) patent(s)
which may be required to implement this document. However, implementers are cautioned that this may not
represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
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.
iv
ISO/FDIS 21740:20242025(en)
Introduction
0.1 Overview
Human-inhabited and inhabitable space stations and space capsules are exposed to the risk of collision with
new launch vehicle stage(s) and spacecraft during their launch and early orbit phase. While such collision
threats also exist during on-orbit spacecraft operations, the launch and early orbit phase is unique in that
potential collisions with inhabitable space stations and space capsules can be avoided at minimal cost (i.e.
without the expenditure of on-orbit manoeuvring fuel) through the proper selection of suitable launch times.
[1[1]]
Consistent with Clause B.5 of the United Nations Long Term Sustainability guidelines and to protect human
missions from the danger of collision with newly launched objects, the LCOLA approving agent may apply
launch collision avoidance (LCOLA) methods to assess either collision risk, close approach, or both. If this
assessment determines that launch at certain times would incur unacceptable risk to the human missions, the
LCOLA approving agent may delay the time of launch.
In addition to establishing requirements for the safety LCOLA process, Annex AAnnex A provides details on
algorithms, processes, and screening criteria that may be used to conduct safety LCOLA assessments.
Annex AAnnex A is intended to ensure the safety and integrity of human-inhabited or inhabitable space
stations.
Annex BAnnex B provides additional details on algorithms, processes, and screening criteria that may be used
to conduct mission assurance LCOLA assessments. Annex BAnnex B is intended to ensure the safety and
integrity of both the newly launched space objects and any on-orbit active spacecraft that can potentially
collide with the launched objects for the initial LCOLA screening time period, and also to reduce the risk of
unintended fragmentation events caused by collision of the newly launched space objects with orbital debris
during that same initial screening period. A selection of general procedures for the determination of
unacceptable risk that result in the identification of all collision-safe launch opportunities is described.
0.10.2 Breakdown of space safety constituents across ISO standards
The space flight safety-relevant topics of Space Traffic Coordination,space traffic coordination (STC), on-orbit
collision avoidance, and launch collision avoidance are closely related. To minimize duplication and maximize
document consistency, the various content that serve as the basis for these three disciplines has been divided
up as shown in Figure 1.
v
ISO/FDIS 21740:2025(en)
NOTE ISO 9490 and ISO 23705 are under development.
Figure 1 — Division of space safety operations content spanning several ISO standards
vi
Final DRAFT International Standard ISO/FDIS 21740:2024(en)
Space systems — Launch window estimation and collision avoidance
1 Scope
This document establishes the general safety launch collision avoidance (safety LCOLA) requirements for the
avoidance of collision between the collection of newly launched objects resulting from a space launch
([including launch vehicle stage(s) and payloads or released objects)] and human-inhabited or human-
habitable space stations and space vehicles.
The document specifies the requirements for the analysis of launch times and procedures for identifying safe
launch opportunities. It also describes the assessment and constraints for collision avoidance risk evaluation
metrics (launch collision probability and standoff distance).
2 Normative reference
There are no normative references in this document.
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 3.1
conjunction
event where the positional separation between two objects is at a local minimum and that minimum is either
(a) closer than a specified minimum distance threshold, or (b) the estimated probability of collision at this
local minimum exceeds a specified launch collision probability (3.5(3.5)) threshold
3.2
3.2
integrated LCOLA
integrated launch collision avoidance
composite launch window (3.9) stemming from the combination of safety launch collision avoidance (safety
LCOLA (3.15) (3.13)) and mission assurance launch collision avoidance (mission assurance LCOLA (3.13) (3.11))
analyses
3.3 3.3
miss distance
minimum approach distance between a launching body and an orbiting body at their closest approach point
3.4 3.4
launch collision avoidance
LCOLA
process of mitigating the risk of collision between the newly launched objects resulting from a space launch
and any space objects in their paths
ISO/FDIS 21740:2025(en)
3.5 3.5
launch collision probability
quantification of the likelihood that a newly launched object would impact a designated space object during a
conjunction (3.1(3.1))
Note 1 to entry: Guidance, winds aloft, performance, estimated orbit propagation accuracy, and conjunction approach
geometry are examples of pre-launch launch vehicle (3.7) system errors.
3.6 3.6
launch period
selected range of dates when a launch is planned
3.7 3.7
launch vehicle
An integrated system that is designed to carry payloads into and beyond its gravitational attracting body’s
atmosphere.
Note 1 to entry: Such systems are typically composed of multiple stages.
3.8 3.8
launch vehicle stage
A launch vehicle (3.7(3.7)) component that has achieved flight above 150 km.
3.9 3.9
launch window
range(s) of times on a day within the launch period (3.6(3.6)) which adhere to all launch vehicle (3.7,), payload,
and mission constraints, and during which the launch range is available and payloads and the launch vehicle
are ready for launch
3.10 3.10
launch window closure
portion of the launch window (3.9(3.7)) which is unavailable (closed) due to a constraint violation
Note 1 to entry: Minimum LCOLA standoff distance (3.17) and launch collision probability (3.5) threshold are examples of
constraints.
3.11 3.11
launch window opportunity
portion of the launch window (3.9(3.7)) which is available (open) because no launch range, launch vehicle
(3.7,), payload or mission constraints are violated
3.12 3.12
LCOLA approving agent
entity who sets requirements for, monitors, and approves the procurement, management, oversight,
implementation, operations, performance evaluation, quality assurance, and monitoring functions of the
LCOLA system under theirits authority.
Note1 Note 1 to entry: The LCOLA approving agent’s responsibilities can be handled by a commercial, non-governmental,
governmental, or international individual or entity, as well as a mandated or delegated entity assigned by applicable
national regulations.
3.13 3.13
mission assurance LCOLA
mitigation of collision risk between the newly launched objects resulting from a space launch and any space
objects in their paths
ISO/FDIS 21740:20242025(en)
Note 1 to entry: The assessment is conducted to ensure the safety and integrity of both sets of objects.
3.14 3.14
primary object
one out of the collection of newly launched objects resulting from a space launch to be protected from a
collision by the applied LCOLA analysis approach
Note 1 to entry: Launch vehicle stage(s) (3.8) and associated released space debris, mission payloads, platforms, and
deployment-related space debris are examples of primary objects.
3.15 3.15
safety LCOLA
assessment of collision risk between the newly launched objects resulting from a space launch and any
inhabited or inhabitable space objects in their paths
Note 1 to entry: The assessment is conducted to ensure the safety and integrity of both sets of objects.
3.16 3.16
secondary object
one out of a set of designated spac
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