ISO 11227:2012

Space systems — Test procedure to evaluate spacecraft material ejecta upon hypervelocity impact

ISO 11227:2012 describes an experimental procedure for assessing the behaviour, under orbital debris or meteoroid impacts, of materials that are intended to be used on the external surfaces of spacecraft and launch vehicle orbital stages. ISO 11227:2012 provides a unified method by which to rank materials. The ejecta production characteristics of different materials are compared under standardized conditions in which test parameters are fixed to one number. Optional tests with different parameters are also useful for the proper selection of materials in other conditions, and they could be performed as research items. ISO 11227:2012 establishes the requirements to be satisfied for the test methods in order to characterize the amount of ejecta produced when a surface material is impacted by a hypervelocity projectile. Its purpose is to evaluate the ratio of ejecta total mass to projectile mass, and the size distribution of the fragments. These are the necessary inputs for modelling the amount of impact ejecta that a surface material might release during its orbital lifetime, thereby helping to assess its suitability for space use while mitigating the production of small space debris. The purpose of ISO 11227:2012 is to provide data that need to be taken into account in the selection of outer spacecraft materials, though the selection is not based on these criteria alone. The experimental procedure defines the type of facility to be used, the size, velocity and type of projectile to be used, the evaluation of impact ejecta released, the reporting of test results, and the quality requirements to be used. ISO 11227:2012 is applicable to spacecraft and launch vehicles operating in all types of Earth orbits.

Systèmes spatiaux — Mode opératoire d'essai pour l'évaluation des éjectats de matériaux des véhicules spatiaux résultant d'impacts à hypervitesse

General Information

• Status: Published
• Publication Date: 10-Sep-2012
• 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 7 - Orbital Debris Working Group
• Current Stage: 9060 - Close of review
• Start Date: 03-Jun-2028

Relations

• Amended By: ISO 11227:2012/Amd 1:2021 - Space systems — Test procedure to evaluate spacecraft material ejecta upon hypervelocity impact — Amendment 1: Oblique impacts and Annex C update
• Effective Date: 14-Jul-2018

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 11227
First edition
2012-09-15
Space systems — Test procedure to
evaluate spacecraft material ejecta upon
hypervelocity impact
Systèmes spatiaux — Mode opératoire d’essai pour l’évaluation des
éjectats de matériaux des véhicules spatiaux résultant d’impacts à
hypervitesse
Reference number
ISO 11227:2012(E)
ISO 2012
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ISO 11227:2012(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2012

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,

electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISO’s

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Published in Switzerland
ii © ISO 2012 – All rights reserved
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ISO 11227:2012(E)
Contents Page

Foreword ............................................................................................................................................................................iv

Introduction ........................................................................................................................................................................ v

1 Scope ...................................................................................................................................................................... 1

2 Normative references ......................................................................................................................................... 1

3 Terms, definitions, abbreviated terms and symbols .................................................................................. 1

3.1 Terms and definitions ......................................................................................................................................... 1

3.2 Abbreviated terms ............................................................................................................................................... 3

3.3 Symbols ................................................................................................................................................................. 3

4 General requirements ......................................................................................................................................... 3

5 Calibration ............................................................................................................................................................. 4

5.1 General ................................................................................................................................................................... 4

5.2 Impact parameters .............................................................................................................................................. 4

5.3 General environment .......................................................................................................................................... 4

5.4 Ejecta characterization ...................................................................................................................................... 5

5.5 Report of calibration tests ................................................................................................................................ 5

6 Experimental procedure .................................................................................................................................... 5

6.1 General ................................................................................................................................................................... 5

6.2 Impact parameters .............................................................................................................................................. 5

6.3 General environment .......................................................................................................................................... 6

6.4 Ejecta characterization and evaluation ......................................................................................................... 6

6.5 Additional tests .................................................................................................................................................... 7

6.6 Analysis of test results ...................................................................................................................................... 7

7 Reporting of test results .................................................................................................................................... 8

7.1 General ................................................................................................................................................................... 8

7.2 Report of testing of materials .......................................................................................................................... 8

7.3 Database ................................................................................................................................................................ 9

8 Quality assurance ............................................................................................................................................... 9

8.1 General ................................................................................................................................................................... 9

8.2 Quality requirements .......................................................................................................................................... 9

Annex A (informative) Characterization of material ejected upon impact (ejecta) .......................................... 11

Annex B (informative) Example of an ejecta model ................................................................................................13

Annex C (informative) Ejecta measurement methods ............................................................................................16

Annex D (informative) Example of a data sheet .......................................................................................................20

Annex E (informative) Technical data ..........................................................................................................................22

Bibliography .....................................................................................................................................................................23

© ISO 2012 – All rights reserved iii
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ISO 11227:2012(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.

International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.

The main task of technical committees is to prepare International Standards. Draft International Standards

adopted by the technical committees are circulated to the member bodies for voting. Publication as an

International Standard requires approval by at least 75 % of the member bodies casting a vote.

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.

ISO 11227 was prepared by Technical Committee ISO/TC 20, Aircraft and space vehicles, Subcommittee

SC 14, Space systems and operations.
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ISO 11227:2012(E)
Introduction

Throughout its orbit lifetime, any spacecraft is exposed to the risk of collision with man-made space debris

and natural micrometeoroids. Concentration of natural particles is nearly stable, but the amount of man-made

debris is likely to increase over time. Details concerning this space environment can be found in the documents

cited in the bibliography (see References [1] and [2]).

Damage caused by meteoroids or debris can result in total or partial mission failure and in a potential generation

of small debris. Because of the large collision velocities (hypervelocity domain), even a small object produces

upon impact a large amount of small particles, which are called ejecta. Ejecta can damage parts of the spacecraft

itself and increase the population of space debris. The orbital lifetime of the ejecta depends on several factors

such as size, initial velocity, and orbit altitude of the parent body. This population of space debris is already

[3][4][5]

evaluated at a few percent of the total space debris population and it is likely to increase in the future . It is

therefore necessary, for the mitigation of such particles, to assess the mechanism of their production.

[6][7][8]

As shown by previous experimental studies , the amount of ejecta depends primarily on the type of

material exposed directly to the space environment. It is greater for brittle materials than for ductile materials;

it depends also on the size and on the velocity of impacting particles. Consequently, the best approach for

assessing the process is to perform laboratory impact simulation using hypervelocity launchers.

The purpose of this International Standard is to describe a standard approach for assessing the behaviour,

under orbital debris or meteoroid hypervelocity impacts, of the materials that are used on the external surfaces

[9]
of spacecraft .

Results obtained from the standard tests carried out on as wide a range of materials as possible will be stored

in a database created for this purpose, or incorporated into an existing one such as ECSS-Q70-71A (see

Annex D and Reference [10]). This database will help designers choose spacecraft outer materials that mitigate

the risk of space debris.
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INTERNATIONAL STANDARD ISO 11227:2012(E)
Space systems — Test procedure to evaluate spacecraft
material ejecta upon hypervelocity impact
1 Scope

This International Standard describes an experimental procedure for assessing the behaviour, under orbital

debris or meteoroid impacts, of materials that are intended to be used on the external surfaces of spacecraft and

launch vehicle orbital stages. This International Standard provides a unified method by which to rank materials.

The ejecta production characteristics of different materials are compared under standardized conditions in

which test parameters are fixed to one number. Optional tests with different parameters are also useful for the

proper selection of materials in other conditions, and they could be performed as research items.

This International Standard establishes the requirements to be satisfied for the test methods in order to

characterize the amount of ejecta produced when a surface material is impacted by a hypervelocity projectile.

Its purpose is to evaluate the ratio of ejecta total mass to projectile mass, and the size distribution of the

fragments. These are the necessary inputs for modelling the amount of impact ejecta that a surface material

might release during its orbital lifetime, thereby helping to assess its suitability for space use while mitigating

the production of small space debris.

The purpose of this International Standard is to provide data that need to be taken into account in the selection

of outer spacecraft materials, though the selection is not based on these criteria alone.

The experimental procedure defines
— the type of facility to be used,
— the size, velocity and type of projectile to be used,
— the evaluation of impact ejecta released,
— the reporting of test results, and
— the quality requirements to be used.

It is anticipated that this International Standard will be the first of several test procedure standards aimed at

characterizing the release of small debris from the external surfaces of spacecraft and launch vehicle orbital

stages as the result of interaction with the space environment. It is applicable to spacecraft and launch vehicles

operating in all types of Earth orbits.
2 Normative references

The following referenced documents are indispensable for the application 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 24113, Space systems — Space debris mitigation requirements
3 Terms, definitions, abbreviated terms and symbols
3.1 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 24113 and the following apply.

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ISO 11227:2012(E)
3.1.1
brittle material
material that breaks due to a propagation defect under the action of a stress
3.1.2
ductile material

material that can be plastically deformed without breaking under the action of a stress

3.1.3
ejecta cone

shaped spray of fine particles, comprising fragments and spalls that are released during a high-velocity impact.

3.1.4
fragmentation

process by which an orbiting space object dissociates and produces debris, such as break-up, exposure to

space environment, and ageing
3.1.5
hypervelocity impact

impact occurring with a velocity greater than the velocity of sound in any given material

3.1.6
impact crater

damage left on a material, generally hemispherical in shape, after a projectile has hit its surface without going

throughout the material
3.1.7
light gas gun
LGG

experimental device consisting of a powder gun that compresses a low-density gas to accelerate a projectile

up to hypervelocities
3.1.8
meteoroid

particles of natural origin, resulting from the disintegration and fragmentation of comets and asteroids, which

orbit the sun
3.1.9
perforation

hole created by an impact on a thin material in which there is no formation of a crater

3.1.10
plasma gun

experimental device that produces an accelerated plasma flow, which is compressed in a coil and then drags

a projectile up to hypervelocities
3.1.11
silica aerogel

low-density solid material, made with a porous, silica-based structure, used for the retrieval of ejecta fragments

in impact experiments
3.1.12
spall

piece of material broken and ejected upon high-velocity impact, usually by stress waves, mainly on brittle material

NOTE If the resulting tensile stress caused by the reflection of the compression wave on the surface (front or back)

exceeds the tensile strength of the material, a thin sheet of material separates from the target and is ejected.

3.1.13
specimen
target

representative sample of a spacecraft material that is used in impact experiments

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ISO 11227:2012(E)
3.1.14
stress
force exerted on a body that tends to strain or to deform its shape.
3.1.15
tensile strength
power to resist tensile stress

NOTE The tensile strength of brittle materials is about two orders of magnitude less than the tensile strength of metals.

3.1.16
tensile stress

stress on a material produced by pulling forces along an axis, which tends to extend or break the material

3.1.17
witness plate

flat sheet of ductile material used in impact experiments to capture ejecta and characterize the resulting damage

3.2 Abbreviated terms
CFRP carbon-fibre-reinforced polymer
HVI hypervelocity impact
LGG light gas gun
MLI multilayer insulation
PVDF polyvinidylene fluoride
3.3 Symbols
M total ejecta mass
K material-type-dependent coefficient (ductile or brittle)

β ratio of the mass ejected from the cone to the total ejected mass from the impact crater

t thickness of test sample
d diameter of projectile
4 General requirements

4.1 If this International Standard is applied during the design of a spacecraft or launch vehicle orbital stage,

then the test procedure and results shall be approved by approving agents and documented in accordance with

the space debris mitigation plan specified by ISO 24113.

4.2 Tests shall be performed at a hypervelocity impact facility that can fully satisfy the experimental procedure.

4.3 Before performing the experimental procedure, a calibration of the hypervelocity impact facility shall be

carried out to provide a reference data point for the subsequent tests at the facility.

4.4 The calibration tests will be used to confirm the facility independencies of the test procedure.

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ISO 11227:2012(E)
5 Calibration
5.1 General

Subclauses 5.2 to 5.5 describe each step of a procedure for calibrating a hypervelocity impact test facility prior

to it performing the experimental procedure described in Clause 6. The use of light gas guns or plasma guns

to perform the tests is acceptable.
5.2 Impact parameters
5.2.1 Perform a test shot using the following projectile parameters:
[11] [12]

a) material: aluminium alloy Al 2017 or Al 2024; the choice is based on ISO 209-1:1989 or JIS H 4040:2006 ;

b) size and shape: 1 mm ± 0,1 mm diameter sphere;
c) impact velocity: 5 000 m/s ± 100 m/s is recommended;
d) impact angle of incidence relative to target normal: 0°.
5.2.2 Use a target with the following characteristics:
a) size: 50 mm (± 1,5 mm) × 50 mm (± 1,5 mm);
b) material: synthetic fused silica glass (see Annex E for details);
c) thickness: 20 mm (± 1,5 mm);
d) attachment: fixed at the edges to a mounting plate.

NOTE The target material is fragile and it is recommended the target be placed in a small box with a window (hole)

to prevent mass measurement error of the target after the impact test.

5.2.3 Use a witness plate with the following characteristics to collect ejecta particles released from the front

side of the target during impact:

a) size: 250 mm × 150 mm, with a circular hole (diameter not greater than 30 mm) cut in the centre in order

to allow the projectile to go through;
[13] [14]

b) material: copper; the choice is based on ISO 197-1:1983 or JIS H 3100:2006 (purity: 99,90);

[15]
c) chemical polishing is recommended ;
d) thickness: 2 mm;

e) distance and position (angle) to the target: 100 mm in front of the target, parallel to the target;

f) attachment: by threaded rods and bolts, fixed on the target holding plate
NOTE See Annex C for details.
5.3 General environment
The general environment shall satisfy the following parameters:
a) operating temperature: room temperature (measurement accuracy: ±5 °C);
b) operating pressure: < 0,1 Pa (recommended).
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ISO 11227:2012(E)
5.4 Ejecta characterization
At a minimum, the following parameters shall be measured:

a) size distribution of diameter of craters created by front-side ejecta particles within the following ranges:

1) between 0,025 mm and 0,05 mm (mainly from the ejecta cone);
2) between 0,05 mm and 0,1 mm (mainly from the ejecta cone);
3) between 0,1 mm and 1 mm (mainly from spall);
4) > 1 mm (from spall).

NOTE More details for the ejecta characterization are given in 6.4 and in Annex C.

5.5 Report of calibration tests
The results shall be summarized in tabular form as shown in Table 1.
Table 1 — Calibration tests
Size of
Total mass
Projectile
crater on
Type of Reference Target
ejected
Date of test Location parameters:
target
facility of test material
velocity, size
xxx xxx xxx xxx xx, xx xx xx xx
6 Experimental procedure
6.1 General

This clause defines an experimental procedure for conducting tests in order to characterize the behaviour of

materials upon hypervelocity impact and in particular to evaluate the amount of ejecta. The use of light gas

guns or plasma guns to perform the tests is acceptable.
6.2 Impact parameters
6.2.1 Perform the shots using the following projectile parameters
[11] [12]

a) material: aluminium alloy Al 2017 or Al 2024; the choice is based on ISO 209-1:1989 or JIS H 4040:2006 ;

b) size and shape: 1 mm ± 0,1 mm diameter sphere;
c) impact velocity: 5 000 m/s ± 100 m/s;
d) impact angle of incidence relative to target normal: 0°.
6.2.2 Use a target with the following characteristics:
a) size: at least 50 mm × 50 mm, in order to avoid edge effects upon impact;
b) material: representative of the material to be used on the spacecraft;
c) thickness: representative of the material to be flown;
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ISO 11227:2012(E)

NOTE The ejecta process depends on the ratio of target thickness to projectile diameter (t/d); in the case that

there is a perforation of the sample under test, it is necessary to evaluate the amount of ejecta from the front side and

from the rear side.
d) attachment: held in place by fixing at the edges only;

e) rear side left free to allow collection of ejecta if perforation or rear-side spall occurs.

6.2.3 Use a witness plate with the following characteristics to collect ejecta particles released from the front

side and from the rear side of the target during impact:

a) size: 250 mm × 150 mm, with a circular hole (diameter not greater than 30 mm) cut in the centre of the front

witness plate in order to let the projectile go through;
[13] [14]

b) material: copper; the choice is based on ISO 197-1:1983 or JIS H 3100:2006 (purity: 99,90);

[15]
c) chemical polishing is recommended ;
d) thickness: 2 mm;

e) distance and position (angle) to the target: 100 mm in front of and parallel to the target plane;

f) similarly, a witness plate shall be placed behind the target;
g) attachment: by threaded rods and bolts, fixed on the target holding plate.
NOTE More details are given in Annex C.
6.3 General environment
The general environment shall satisfy the following parameters:

a) operating temperature: room temperature or defined by user (measurement accuracy: ± 5 °C);

b) operating pressure: < 0,1 Pa (recommended).
6.4 Ejecta characterization and evaluation

6.4.1 To characterize and model the production of ejecta, it is appropriate to choose relevant parameters that

are based on the physics of the impact process (more details are given in Annexes A and B).

6.4.2 At a minimum, the following parameters shall be measured:

a) The total amount of ejecta, M , which is obtained by measuring the target mass before and after the test.

Of course, part of the material ejecta comes from the projectile itself. This contribution is, however, small

in comparison with material coming from the target (less than 1 %).

b) The size distribution of craters. On the witness plate used to characterize the ejecta, the size distribution

of the diameter of craters formed by the front-side and rear-side ejected particles is determined within the

following ranges:
1) between 0,025 mm and 005 mm (mainly from the ejecta cone);
2) between 0,05 mm and 0,1 mm (mainly from the ejecta cone);
3) between 0,1 mm and 1 mm (mainly from spall);
4) >1 mm (from spall).

NOTE 1 As an option, the average velocity of the ejecta can also be measured. At present, it is not possible to measure

the ejecta velocity within each crater diameter range specified. Only the bulk velocity (of cone and spall fragments) can be

measured using active velocity sensors or high-speed video recording.
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ISO 11227:2012(E)

NOTE 2 Annex C describes in more details measurement methods that can be employed in the determination of

ejecta parameters.

6.4.3 The fundamental analysis of test results shall be documented in tabular form as shown in Table 2.

Table 2 — Fundamental analysis of test results
Total amount Target mass before Target mass after
of ejecta (mg): M xxx impact (mg) xxx impact (mg) xxx
Size distribution of 0,025 mm 0,05 mm 0,1 mm
> 1 mm
crater diameter, D to 0,05 mm to 0,1 mm to 1 mm
Front side,
xxx xxx xxx xxx
number of craters
Rear side,
xxx xxx xxx xxx
number of craters
Projectile mass (mg) xxx
xxx values to be filled in after the tests

When using copper witness plates to record the impact craters produced by the ejecta, the size of the fragments

(d) can be derived from the size of the impact craters (D). However, the ratio of crater diameter to projectile

diameter (D/d) depends on the impact velocity (v). A commonly used conversion equation is the following:

0,68
D/d = 1,28v (v in km/s)

NOTE 1 Since the determination of the velocity of ejecta fragments is currently difficult, the determination of particle

diameter is therefore still imprecise. The next edition of this International Standard will be amended as more accurate

velocity measurements become available.

When crater diameters are converted into particle diameters, the results shall be given in a table similar to

Table 2. Details and rationale are given in Annex C, Table 2, and in References [16] to [18].

NOTE 2 As an option, soft or low-density material such as foam or silica aerogel can be used to ensure intact recovery

of ejecta fragments. In this case, fragment sizes can be sieved and measured and their size will be the average of the

maximum and minimum length or diameter for near-spherical fragments.
6.5 Additional tests

In order to investigate the ejecta process in more detail, if the facility is able to perform such tests, it is

recommended that the following additional tests be performed:
a) incidence angle varying from 0° to 75°, in 15° steps;
b) velocity varying from 1 km/s to 16 km/s.
6.6 Analysis of test results

The applicability of statistical methods to the evaluation of numerical results usually depends on the number

of tests performed on a specific material for a specific set of test conditions; this should be large enough to

constitute a statistically significant sample. Due to the complexity and cost of hypervelocity impact testing, only

a limited number of tests need be performed on each sample.
A minimum of three shots shall be performed at normal incidence.
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ISO 11227:2012(E)
7 Reporting of test results
7.1 General

The report shall provide all information relevant to the understanding and correct interpretation of the test

activity and test results. It shall contain the following:
a) an abstract summarizing the test procedure and findings;

b) an introduction providing the background information to the test (i.e. reason for testing, use and

applicability of results);
c) the objective of the test activity;
d) information on the tested material;
e) a description of the test procedure and test conditions;
f) the calibration report;
g) a presentation of the results, as shown in Table 2;
h) a discussion of the results;
i) conclusions and recommendations;
j) numerical data in a format agreed by the customer;
k) the customer’s authorization for the tests.
7.2 Report of testing of materials
7.2.1 Information on test sample

The report should include the following information on the test material and on the witness plate, as provided

by the supplier:
a) supplier’s name and code;
b) material standard designation;
c) date of batch manufacturing;
d) specified chemical composition;
e) material and heat treatment specifications:
1) surface treatment, if any;

2) description of other manufacturing processes (e.g. welding, cutting and milling);

3) non-destructive inspection before the tests;
4) safety information and handling notice.
7.2.2 Description of test procedures

The report shall provide a description of specimen preparation, test equipment and test procedure. The

information provided shall be in accordance with the requirements specified in the relevant subclauses of this

International Standard.
Estimated values of precision and bias for the test results shall be included.
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ISO 11227:2012(E)
Anomalies and deviations from test procedures shall be reported.
7.2.3 Presentation of test results

The test results shall be presented in the report in an appropriate format (e.g. tables, drawings, plots, diagrams

and photos), together with a written description.

Units of measure and scales shall be consistent and in accordance with the SI system of units, which should

be consistent and in accordance with customer specifications.
7.3 Database

The test results should be provided to standards organizations that maintain databases on spacecraft materials

[10]
such as ECSS-Q-70-71A and made publicly available.

The test results should be provided in an electronic format that can be incorporated into such databases.

[10]

Annex D gives an example of a material data sheet from the standard ECSS-Q-70-71A .

8 Quality assurance
8.1 General

The test facility shall implement the quality assurance, inspection and quality control procedures specified herein before

conducting any test activity. The implementation of these procedures shall be ma
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