© gmv, 2008 property of gmv all rights reserved issues in flight dynamics: collocation operations...

© GMV, 2008 Property of GMV

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ISSUES IN FLIGHT DYNAMICS:

COLLOCATION OPERATIONS & MISSION ANALYSIS A SUPPLIER’S PERSPECTIVE

Gonzalo Garcia, VP of Operations, USAAssaf Barnoy, Lead Flight Dynamics Engineer

AIAA SOSTC 2008


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AGENDA

© GMV, 2008

Introduction to GMV

Introduction to focusSuite

Introduction to Flight Dynamics and Collocation Analysis

Collocation Assessment: Matool

Collocation Operations: COLLOC, INICOL, and CLOSEAP

Lessons Learned

AGENDA

2008/04/16 FLIGHT DYNAMICS COLLOCATION: ASSESSMENT AND OPERATIONS


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INTRODUCTION TO GMV

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GLOBAL REACH, GLOBAL PRESENCE

Global Locations GMV staff permanently located

in 7 countries GMV systems deployed in 5

continents, 18 countries Pronounced world business US subsidiary (ITAR OK)

Main Customers

Space Agencies Industrial Primes Integrators Commercial Satellite operators Space App. Communities


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OUR OFFER

Mission Analysis studies and mission analysis tools (station keeping, collocation, launch window analysis, …)

Operational systems for satellite control (inc. on-station and LEOP):– Real-Time TM/TC M&C– Flight Dynamics– Mission Planning and

Scheduling Special operational needs (e.g.

collision prediction/analysis, rendezvous, interstellar)

Satellite capacity management:– Satellite capacity management– Payload Reconfiguration– CFDP

Operations support

focus



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INTRODUCTION TO focusSuite

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• focusSuite is an off-the-shelf product, which supports multi-mission, multi-satellite flight dynamics operations and mission analysis

• focusSuite’s benefits include functionality, reliability, flexibility and user friendliness

• focusSuite provides full lifecycle (assessment to launch to de-orbiting) flight dynamics operations support through a collection of flight proven mission independent and mission/spacecraft specific functionality

• focusSuite provides high degree of configurability allowing to provide custom solutions

• focusSuite also provides a generic framework that allows for extensibility of product development and evolution

• focusSuite includes an Open API which increases productivity, stability, and accessibility, including integration into a service oriented architecture (SOA)

focusSUITE

FLIGHT DYNAMICS: focusSuite PRODUCT LINE


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focusSuite: A COMPLETE PRODUCT LINE

FDS product line – focusSuite: advanced multimission, multisatellite

FD infrastructure providing core functions– focusGEO: GEO operations– focusLEOP: LEOP operations– focusLEO: LEO operations– focusCn: satellite constellations– and more

– focusCloseap: collision risk prediction– COLLOC: Collocation Assessment– INICOL: Collocation Initialisation control– MATOOL: Station Keeping and collocation

assessment

Selected to operate over 120 satellites


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Three-tier architecture, to promote flexibility and modularity, allow distribution and scalability:– 1st Tier: Presentation (clients)– 2nd Tier: Process management– 3rd Tier: Data management / Computation.

Normally includes legacy code based on reliable flight dynamics algorithms

Advanced API for interaction with Process Manager– Operator Manual Access (GUI)– Automatic Procedures (Autofocus) – External Applications (including SOA)

focusSuiteModules

DataManager

Process Manager

GUI

focusGEOModules

focusLEOModules

focusCnModules

Autofocus

focusAPI

ExternalApp.

focusSuite: ARCHITECTURE

EventManager

COLLOC INICOL CLOSEAP MATOOL



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INTRODUCTION TO FLIGHT DYNAMICS AND COLLOCATION

© GMV, 2008

COLLOCATION OPERATIONSWhen planning to collocate spacecraft the following factors

should be considered: The number of participating spacecraft The size of the control windows The duration/frequency of the station keeping control cycle Various other constraints on thruster design, such as the firing

duration, minimum time between maneuvers, Sun-Earth angle, etc.

All of which translate to direct effect on the operator: Benefit in added capacity Added redundancy More complex station-keeping operations


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COLLOCATION REQUIREMENTS

There are two levels of requirements that must be considered: Mission Requirements

– Keep the satellites inside the control box during their lifetime– Fit the geometrical configuration of the control strategies and

fulfil their design requirements– Minimize the fuel consumption of each satellite

Safety & interference criteria– The probability of an approach closer than a given threshold

(safety margin) between any pair of satellites shall be negligible

– The probability of disturbance on infra-red sensors, sun sensors, solar arrays or antennas shall be negligible


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Complete Longitude Separation Partial Longitude Separation

COLLOCATION STRATEGIES:Longitude Separation


OR

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COLLOCATION STRATEGIES: Inclination/Eccentricity Separation Separation in Inclination Separation in Eccentricity Combined Inclination and Eccentricity separation


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Collocation by eccentricity offset ensures that radial and tangential separation are never low at the same time.

Radial Sep. = 0

Tangential sep. = max

Radial Sep. = max

Tangential Sep. = 0


COLLOCATION STRATEGIES: Inclination/Eccentricity Separation (cont)

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GMV offers two levels of collocation support: MATOOL: Mission Analysis Tool including Collocation, which

analyzes collocation control to determine viability of collocation plan and proposes spacecraft operations control

COLLOC, INICOL, and CLOSEAP: Operational functions (part of focusGEO), which allow operators to observe and control a spacecraft collocation group


GMV’s SOLUTION TO COLLOCATION


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COLLOCATION ASSESSMENT:

MATOOL

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WHAT IS MATOOL?

MATOOL isgeostationary satellites.

Its main features include:

Full station keeping analysis (including delta V and mass consumption)

Extended simulation period (could span entire spacecraft lifetime)

Study of multiple spacecraft orbits, including inclined

Output is available in data files and plot format, and includes evolution data of orbital elements, manoeuvres, and inter-satellite variables for all satellite pairs

a station keeping and collocation analysis tool for


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MATOOL: MISSION ANALYSIS SUPPORT

Evaluation of the inclination control strategy (N/S) and the drift/eccentricity control strategy (E/W)

The performance of those strategies is evaluated based on orbit determination errors and thrusters behavior (thrust efficiency and cross-coupling effects)

Analysis and feasibility of the collocation strategy for several satellites, including safety constraints in terms of minimum inter-satellite distance and separation angles

Verification of the restrictions associated with the window control

Attitude constraints analysis

Complete lifetime estimation


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MATOOL: EXECUTION MODES

Collocation Parameters: The objective of this mode is to provide an initial estimate of the collocation control parameters for a cluster of satellites.

Proximity Analysis: The objective of this mode is to perform proximity analysis for a collocation group.

Complete Execution: The objective of this mode is to perform a long term simulation of the station-keeping strategy and collocation monitoring. This computes maneuver, orbit, and proximity evolution for all satellites.

– Monte Carlo Analysis: A Monte Carloanalysis option is available from the Complete Execution mode. This method makes use of random numbers and probability statistics to investigateproblems.


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MATOOL: FUNCTIONALITIES

Maneuvers computation / orbit propagation / collocation analysis

Free Inclination drift management (no inclination control strategy)

Ionic/Chemical propulsion

External Maneuvers File integration. Results from other tools can be easily integrated for analysis

Generic Maneuver Calibration avoiding dependencies on a particular platform

Safety parameters estimation


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MATOOL: USER INTERFACEInput PanelUsers have access to input parameters to define the mission profile, including number of satellite, orbit plans, maneuver station keeping information, and more

Tests GroupsUsers can create multiple test groups/scenarios to address different missions, operational concepts, and collocation profiles

Analysis to OperationsInput parameters are 100% compatible with focusSuite operational products (focusGEO), thereby allowing for simple transition from analysis to operations

Analysis OutputDetailed analysis output is available in detailed execution walkthrough, data tables, and graphical displays


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MATOOL: USER INTERFACE


Longitude / Latitude Histograms

Show percentage of time spent within each subinterval within the box

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Eccentricity evolution

Show evolution of eccentricity vector for all satellites in the collocation group. Both mean and osculating elements.

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Inclination evolution

Show evolution of inclination vector for all satellites in the collocation group. Both mean and osculating elements.

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Delta of inclination and eccentricity

Show separation in eccentricity and inclination vectors for all satellite pairs in the collocation group.

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Inters-satellite separation

Show inter-satellite distance and angular separation for all satellite pairs in the collocation group.

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MATOOL: OPERATIONAL EXPERIENCE EUTELSAT:

– Mission analysis of the satellite fleet (20+ satellites), in particular for collocation analysis. Includes a collocation group of 5-6 satellites.

ESA:– Goal to analyze the feasibility of ‘cluster’ concept for a GEO mission– MATOOL used to assure a continuous inter-satellite link

SS/LORAL:– Mission analysis study performed by GMV and proposed operational

concept delivered in formal report to SS/LORAL

Orbital Sciences Corporation:– Analysis tool for new GEO missions

Other GEO operators: – Superbird– Worldspace– OPTUS– HISPASAT


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Purpose:

Performs a proximity check for satellites within a collocation group Used also to monitor collocation groups of satellites from different

operators

Options:

Under/Over-performance of maneuvers – used to allow for thruster efficiency in collocated satellites

Inter-satellites parameters (other satellites defined by Collocation File) Angular satellite separation based on specified station visibility

Output: Complete statistical review of the collocation of all satellites in cluster If close approach is detected, a maneuver will be computed to avoid

collision Detailed graphical displays indicating collocation status

COLLOC: COLLOCATION ANALYSIS

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COLLOC: COLLOCATION ANALYSIS

COLLOC Report:

Single page printout includes orbit data for all participating satellites Inter-satellite distance and angular separation for all satellite-pairs Details about any avoidance manoeuvres needed, including improved collocation

statistics

COLLOC Plots: Orbit plots Collocation plots Latitude vs. Longitude plots Latitude/Longitude histograms Inter-satellite distance histogram

© GMV, 2008

INICOL: COLLOCATION CLUSTER INITIALIZATION


Purpose:

Compute the maneuvers needed for the collocation strategy initialization and extraction

Options:

Collocation control parameters Maneuver Mode: N/S, E/W (Drift & SK Initialization) and E/W (Only SK

Initialization) Constraints on operations (e.g. Next operational Station Keeping

maneuver)

Output: Computed maneuver(s) to achieve desired target Collocation analysis with other spacecraft of proposed maneuver to

determine close approaches

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Two Operation Modes: – Satellite Insertion: To insert a satellite in a new or existent cluster

finding the nominal position in Eccentricity, Longitude & Inclination– Satellite Extraction: To extract a satellite from a shared cluster in a

safe manner

Proximity analysis is performed according to collocation data for all satellites in the cluster. Satellites defined by detailed orbital ephemeris (for controlled satellites) and longitude control boxes (for observed satellites).

INICOL: COLLOCATION CLUSTER INITIALIZATION


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CLOSEAP: CLOSE APPROACH PREDICTION

Purpose:

Predict close approaches between the satellite and third party objects

Options:

Automatic download of latest TLE elements from SPACETRACK, including all observable objects

Phased approach allows for consideration of many parameters in a short span of time

Output: Computed close approach report with any object Probability of collision using covariance analysis Collocation and orbit plots with any nearby object Status messages sent by email to selected users

© GMV, 2008


LEVEL 2: SPHERE

LEVEL 3: ELLIPSOID

LEVEL 1: BOX

Internet OperationalOrbital Data

User 1 User 3User 2

TLEs

Ephemeris /State Vector + Manoeuvres

CollisionRisk

AssessmentReport

FDS

focusCloseAp

Automatic processing

Phased approach

© GMV, 2008


Output: Plots

• Separation plots between satellite and tracked objects

• Orbit plots showing evolution of satellite and tracked objects

• Avoidance manoeuvre

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OPERATIONAL COLLOCATION EXPERIENCE

EUTELSAT:– Collocation group of 5-6 satellites has been

operated with focusGEO successfully since 2001HISPASAT:

– At one point 4 satellites in collocation operated by focusGEO

WorldSpace:– Asiastar closely monitors close approaches to a

collocated satellite from another operator using CLOSEAP / COLLOC

Soon: – Telenor and MEASAT will be monitoring collocated satellites with

focusGEO


© GMV, 2008

LESSONS LEARNED A thorough detailed mission analysis

study is necessary long before launch to define the optimal strategies that guarantee:– Minimum propellant consumption (=

maximum life)– Fulfillment of separation constraints

A good combined strategy can make a big difference in expected life of the satellites

MATOOL is an excellent tool for that task. Used for different missions in the USA, Europe, Asia and Australia

The operational implementation of a collocation strategy requires the use of a multi-satellite system capable of planning the maneuvers of all satellites consistently. focusGEO does the job.


© gmv, 2008 property of gmv all rights reserved issues in flight dynamics: collocation operations...

Documents

gmv slide

flight dynamics collocation

gmv introduction

property of gmv

focussuite slide

matool collocation operations

collocation assessment

vp of operations