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ISSUES IN FLIGHT DYNAMICS: COLLOCATION OPERATIONS & MISSION ANALYSIS A SUPPLIER’S PERSPECTIVE

AIAA SOSTC 2008. ISSUES IN FLIGHT DYNAMICS: COLLOCATION OPERATIONS & MISSION ANALYSIS A SUPPLIER’S PERSPECTIVE Gonzalo Garcia, VP of Operations, USA Assaf Barnoy, Lead Flight Dynamics Engineer. AGENDA. Introduction to GMV Introduction to focusSuite

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ISSUES IN FLIGHT DYNAMICS: COLLOCATION OPERATIONS & MISSION ANALYSIS A SUPPLIER’S PERSPECTIVE

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  1. AIAA SOSTC 2008 ISSUES IN FLIGHT DYNAMICS: COLLOCATION OPERATIONS & MISSION ANALYSIS A SUPPLIER’S PERSPECTIVE Gonzalo Garcia, VP of Operations, USA Assaf Barnoy, Lead Flight Dynamics Engineer

  2. AGENDA

  3. 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 FLIGHT DYNAMICS COLLOCATION: ASSESSMENT AND OPERATIONS 2008/04/16 Page 3

  4. INTRODUCTION TO GMV

  5. 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 FLIGHT DYNAMICS COLLOCATION: ASSESSMENT AND OPERATIONS 2008/04/16 Page 5

  6. 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 MissionPlanning and Scheduling Special operational needs (e.g. collision prediction/analysis, rendezvous, interstellar) Satellite capacity management: Satellite capacity management Payload Reconfiguration CFDP Operations support FLIGHT DYNAMICS COLLOCATION: ASSESSMENT AND OPERATIONS 2008/04/16 Page 6

  7. INTRODUCTION TO focusSuite

  8. 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 provenmission independent and mission/spacecraft specific functionality focusSuite provides high degree of configurability allowing to provide custom solutions focusSuitealso 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) FLIGHT DYNAMICS: focusSuite PRODUCT LINE focus SUITE FLIGHT DYNAMICS COLLOCATION: ASSESSMENT AND OPERATIONS 2008/04/16 Page 8

  9. 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 FLIGHT DYNAMICS COLLOCATION: ASSESSMENT AND OPERATIONS 2008/04/16 Page 9

  10. 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) focusSuite: ARCHITECTURE GUI Autofocus External App. focusAPI Process Manager Event Manager Data Manager focusSuite Modules focusGEO Modules focusLEO Modules focusCn Modules COLLOC INICOL CLOSEAP MATOOL FLIGHT DYNAMICS COLLOCATION: ASSESSMENT AND OPERATIONS 2008/04/16 Page 10

  11. INTRODUCTION TO FLIGHT DYNAMICS AND COLLOCATION

  12. COLLOCATION OPERATIONS • When 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 FLIGHT DYNAMICS COLLOCATION: ASSESSMENT AND OPERATIONS 2008/04/16 Page 12

  13. 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 FLIGHT DYNAMICS COLLOCATION: ASSESSMENT AND OPERATIONS 2008/04/16 Page 13

  14. COLLOCATION STRATEGIES:Longitude Separation • Complete Longitude Separation • Partial Longitude Separation OR FLIGHT DYNAMICS COLLOCATION: ASSESSMENT AND OPERATIONS 2008/04/16 Page 14

  15. COLLOCATION STRATEGIES: Inclination/Eccentricity Separation • Separation in Inclination • Separation in Eccentricity • Combined Inclination and Eccentricity separation FLIGHT DYNAMICS COLLOCATION: ASSESSMENT AND OPERATIONS 2008/04/16 Page 15

  16. COLLOCATION STRATEGIES: Inclination/Eccentricity Separation (cont) • 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 FLIGHT DYNAMICS COLLOCATION: ASSESSMENT AND OPERATIONS 2008/04/16 Page 16

  17. GMV’s SOLUTION TO COLLOCATION 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 FLIGHT DYNAMICS COLLOCATION: ASSESSMENT AND OPERATIONS 2008/04/16 Page 17

  18. COLLOCATION ASSESSMENT: MATOOL

  19. WHAT IS MATOOL? a station keeping and collocation analysis tool for • MATOOL is • geostationary 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 FLIGHT DYNAMICS COLLOCATION: ASSESSMENT AND OPERATIONS 2008/04/16 Page 19

  20. 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 FLIGHT DYNAMICS COLLOCATION: ASSESSMENT AND OPERATIONS 2008/04/16 Page 20

  21. 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 Carlo analysis option is available from the Complete Execution mode. This method makes use of random numbers and probability statistics to investigate problems. FLIGHT DYNAMICS COLLOCATION: ASSESSMENT AND OPERATIONS 2008/04/16 Page 21

  22. 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 FLIGHT DYNAMICS COLLOCATION: ASSESSMENT AND OPERATIONS 2008/04/16 Page 22

  23. MATOOL: USER INTERFACE Input Panel Users have access to input parameters to define the mission profile, including number of satellite, orbit plans, maneuver station keeping information, and more Tests Groups Users can create multiple test groups/scenarios to address different missions, operational concepts, and collocation profiles Analysis to Operations Input parameters are 100% compatible with focusSuite operational products (focusGEO), thereby allowing for simple transition from analysis to operations Analysis Output Detailed analysis output is available in detailed execution walkthrough, data tables, and graphical displays FLIGHT DYNAMICS COLLOCATION: ASSESSMENT AND OPERATIONS 2008/04/16 Page 23

  24. MATOOL: USER INTERFACE Longitude / Latitude Histograms Show percentage of time spent within each subinterval within the box FLIGHT DYNAMICS COLLOCATION: ASSESSMENT AND OPERATIONS 2008/04/16 Page 24

  25. MATOOL: USER INTERFACE Eccentricity evolution Show evolution of eccentricity vector for all satellites in the collocation group. Both mean and osculating elements. FLIGHT DYNAMICS COLLOCATION: ASSESSMENT AND OPERATIONS 2008/04/16 Page 25

  26. MATOOL: USER INTERFACE Inclination evolution Show evolution of inclination vector for all satellites in the collocation group. Both mean and osculating elements. FLIGHT DYNAMICS COLLOCATION: ASSESSMENT AND OPERATIONS 2008/04/16 Page 26

  27. MATOOL: USER INTERFACE Delta of inclination and eccentricity Show separation in eccentricity and inclination vectors for all satellite pairs in the collocation group. FLIGHT DYNAMICS COLLOCATION: ASSESSMENT AND OPERATIONS 2008/04/16 Page 27

  28. MATOOL: USER INTERFACE Inters-satellite separation Show inter-satellite distance and angular separation for all satellite pairs in the collocation group. FLIGHT DYNAMICS COLLOCATION: ASSESSMENT AND OPERATIONS 2008/04/16 Page 28

  29. 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 FLIGHT DYNAMICS COLLOCATION: ASSESSMENT AND OPERATIONS 2008/04/16 Page 29

  30. COLLOCATION OPERATIONS: COLLOC INICOL CLOSEAP

  31. COLLOC: COLLOCATION ANALYSIS 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

  32. 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

  33. 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 FLIGHT DYNAMICS COLLOCATION: ASSESSMENT AND OPERATIONS 2008/04/16 Page 33

  34. INICOL: COLLOCATION CLUSTER INITIALIZATION • 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). FLIGHT DYNAMICS COLLOCATION: ASSESSMENT AND OPERATIONS 2008/04/16 Page 34

  35. 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

  36. focusCloseAp CLOSEAP: CLOSE APPROACH PREDICTION • Automatic processing • Phased approach LEVEL 1: BOX LEVEL 2: SPHERE LEVEL 3: ELLIPSOID

  37. CLOSEAP: CLOSE APPROACH PREDICTION Output: Plots • Separation plots between satellite and tracked objects • Orbit plots showing evolution of satellite and tracked objects • Avoidance manoeuvre

  38. OPERATIONAL COLLOCATIONEXPERIENCE • EUTELSAT: • Collocation group of 5-6 satellites has been operated with focusGEO successfully since 2001 • HISPASAT: • 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 FLIGHT DYNAMICS COLLOCATION: ASSESSMENT AND OPERATIONS 2008/04/16 Page 38

  39. LESSONS LEARNED

  40. 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. FLIGHT DYNAMICS COLLOCATION: ASSESSMENT AND OPERATIONS 2008/04/16 Page 40

  41. Thank you

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