BS ISO 16679:2015 pdf download – Space systems — Relative motion analysis elements after LV/SC separation
1 Scope
This International Standard provides relative motion analysis elements after LV/SC separation,ncluding 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.
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.
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.