ISO 16679:2015

INTERNATIONAL ISO
STANDARD 16679
First edition
2015-09-01
Space systems — Relative motion
analysis elements after LV/SC
separation
Systèmes spatiaux — Éléments d’analyse de mouvement relatif après
séparation du LV/SC
Reference number
©
ISO 2015
© ISO 2015, Published in Switzerland
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ii © ISO 2015 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative reference . 1
3 Terms and definitions . 1
4 Abbreviated terms . 1
5 Input for analysis . 2
6 General process . 2
7 Analysis principle . 2
8 Analysis method . 3
8.1 General . 3
8.2 Astrodynamics modelling . 3
8.3 Deviation analysis and identification . 3
8.4 Relative motion simulation . 3
8.4.1 Relative motion analysis period . 3
8.4.2 Deviation . 3
8.4.3 Relative position calculation . 4
8.4.4 Deviation margin of relative position . 4
8.5 Safety evaluation . 4
9 Analysis output . 4
Annex A (informative) Relative motion analysis model . 5
Annex B (informative) Typical combination of deviations . 6
Annex C (informative) Coordinate reference frames and variables . 7
Annex D (informative) **/***-***Preliminary (Final) relative motion analysis report
after separation . 8
Bibliography .10
Foreword
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The committee responsible for this document is ISO/TC 20, Aircraft and space vehicles, Subcommittee
SC 14, Space systems and operations.
iv © ISO 2015 – All rights reserved

Introduction
Relative motion analysis predicts the relative distance after launch vehicle (LV) and spacecraft (SC)
separation. The analysis result offers support to the mission design and operation.
This International Standard provides LV and SC operators and manufacturers with specific elements
and procedures for performing relative motion analysis after LV and SC separation. The intent is to
regulate a common basis and offer a direction.
INTERNATIONAL STANDARD ISO 16679:2015(E)
Space systems — Relative motion analysis elements after
LV/SC separation
1 Scope
This International Standard provides relative motion analysis elements after LV/SC separation,
including analysis input, analysis principle, analysis method and analysis output. It is applicable to the
mission design and verification for the prediction of relative motion after LV/SC separation.
This International Standard focuses on the relative motion between the objects involved in one launch
mission. It does not cover the issues about the collision avoidance between newly launched objects and
on-orbit ones.
2 Normative reference
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 14303, Space systems — Launch-vehicle-to-spacecraft interfaces
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 14303 and the following apply.
3.1
LV/SC separation
event of disconnection between LV/SC under the control of LV
3.2
relative motion analysis
analysis to predict the relative distance of spacecraft(s) to objects (end stage of LV and others generated
during the separation) after the LV/SC separation
3.3
separation velocity
relative speed to LV when separation is completed instantly
4 Abbreviated terms
LV launch vehicle
SC spacecraft
ICD interface control document
RMS root mean square
5 Input for analysis
The following information shall be included as analysis input.
a) Theoretical velocity, position, attitude of LV and (each) spacecraft at the separation moment, which
shall be presented in pre-determined coordinate system. Velocity and position vectors shall be
offered in the format as Vx, Vy, Vz, X, Y, Z. The potential reference frames are offered in Annex C.
b) Separation velocity, mass and inertia characteristics of separation bodies.
c) Deviations of LV and separation parts [mass, thrust, impulse, moment-inertial characteristics
(optional), tailed-effect, etc.].
d) Manoeuvres or other operations which shall affect LV end-stage orbit, related parameters and
sequences.
e) Manoeuvres or other operations which shall affect SC orbit, related parameters and sequences
(optional).
6 General process
In actual flight, relative motion after LV/SC separation is affected by many factors, including certain
operations, deviations, mission profile, etc. on both sides. However, in order to simplify collaborations
in applications of launch services, LV and SC parties shall perform the following processes:
a) LV conducts relative motion analysis without taking into account SC manoeuvre, attitude control,
etc. into account,
b) SC evaluates it does not collide with LV orbital stage or other SC (for multi-SC launch mission)
after separation due to its manoeuvre, attitude control, etc., based on the result of LV relative
motion analysis.
The general process is described in Figure 1, where Party A represents LV and Party B represents SC.
The final safety evaluation should be performed based upon LV’s and SC’s analysis. If necessary input
can be offered, the aforementioned processes a) and b) can be incorporated.
Deviation analysis Relative motion
Astrodynamics
Party A
modelling & identi
ication  analysis
Safety evalutaion
SC operations
Party B
SC evaluation
(maneuver, att. control, etc)
Figure 1 — Flow for relative motion analysis after LV/SC separation
7 Analysis principle
In the analysis principle, safety deserves priority. The analysis shall be in accordance with general
principles for trajectory/orbit analysis (perturbations, astrodynamics, etc.) and shall cover
deviations status.
2 © ISO 2015 – All rights reserved

8 Analysis method
8.1 General
The following content shall be included for relative motion analysis:
— astrodynamics modelling;
— deviation analysis and identification;
— relative motion simulation;
— safety evaluation.
8.2 Astrodynamics modelling
The astrodynamics modelling can be achieved in different coordinate systems. One alternative centroid
motion model in an Earth-fixed coordinate system is offered in Annex A for information. Motion
analysis of different objects should be conducted in the same coordinate system.
Gravity, atmosphere force models and related parameters shall be dealt in accordance with the
trajectory/orbit calculation.
8.3 Deviation analysis and identification
Theoretical parameters shall be applied in normal analysis while deviation status shall be considered to
cover the deviations existing in actual flight. The possible deviations have to be included and necessary
items have to be identified for the relative motion analysis.
Typical deviations for LV shall include the following:
— separation velocity;
— separation attitude (pitch, yaw);
— mass of orbital stage;
— other factors, de-orbit thrust, de-orbit attitude control precision, etc.
8.4 Relative motion simulation
8.4.1 Relative motion analysis period
Relative motion analysis period should be a period of time agreed upon with the SC contractor. It should
be no less than one orbit period.
8.4.2 Deviation
Deviation trajectory calculations are performed to support the analysis on minimum relative distance
between orbital stage and spacecraft. Generally, deviations can be generated in 3 typical manners:
— margin status,
— typical combination of deviations, (note that Annex B offers a combination matrix for information) and
— combination of deviations generated by random sampling method.
8.4.3 Relative position cal
...