ISO 16679:2015

Overview - ISO 16679:2015 (Relative motion analysis after LV/SC separation)

ISO 16679:2015 defines the elements and procedures for performing relative motion analysis following launch vehicle (LV) and spacecraft (SC) separation. It is intended for mission design and verification to predict post‑separation relative motion between objects involved in a single launch mission. The standard explicitly focuses on intra‑mission relative motion and does not address collision avoidance with pre‑existing on‑orbit objects.

Key topics and technical requirements

• Analysis inputs: required data include theoretical velocity, position and attitude of LV and each SC at separation (presented in a predetermined coordinate system), separation velocity, mass and inertia characteristics, and identified deviations (mass, thrust, impulse, attitude, etc.).
• Analysis principle: safety-first approach; use established trajectory/orbit analysis practices (perturbations, astrodynamics) and explicitly cover deviations.
• Analysis method - four mandatory elements:
  • Astrodynamics modelling: select and apply consistent coordinate reference frames (Annex C lists options such as ECEF, J2000, perigee orbital) and gravity/atmospheric/perturbation models.
  • Deviation analysis and identification: identify likely deviations (e.g., separation velocity, separation attitude, orbital stage mass, de‑orbit thrust/attitude).
  • Relative motion simulation: simulate for an agreed analysis period (no less than one orbit), generate deviation scenarios by margin, typical combinations (Annex B), or random sampling, then compute relative positions by subtracting trajectories.
  • Safety evaluation: determine minimum relative distance using deviation margins and compare with agreed safety distance, considering LV/SC dimensions and clearance margins.
• Analysis outputs: international units, distance vs. time plots, conclusions and minimum relative distance. Annex D provides a reporting template.

Practical applications and users

ISO 16679 is used by:

• Launch vehicle manufacturers and operators - to produce LV-side relative motion analyses.
• Spacecraft manufacturers and operators - to evaluate collision risk post‑separation and plan maneuvers/attitude control.
• Mission designers and verification teams - for mission design validation, safety margins, and acceptance criteria.
• Systems and safety engineers - to define separation requirements and interface control data (ICD).

Typical applications include multi‑payload deployments, end‑stage disposal planning, and contractual exchanges of LV/SC separation analysis between parties.

Related standards

• ISO 14303 - Space systems - Launch‑vehicle‑to‑spacecraft interfaces (normative reference cited by ISO 16679)

Keywords: relative motion analysis, LV/SC separation, launch vehicle, spacecraft, astrodynamics modelling, separation velocity, relative position calculation, safety evaluation.