Transcript collocation operations

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
© GMV, 2008 Property of GMV
All rights reserved
AGENDA
© GMV, 2008 Property of GMV
All rights reserved
AGENDA

Introduction to GMV

Introduction to focusSuite

Introduction to Flight Dynamics and
Collocation Analysis

Collocation Assessment: Matool

Collocation Operations: COLLOC,
INICOL, and CLOSEAP

Lessons Learned
FLIGHT DYNAMICS COLLOCATION:
ASSESSMENT AND OPERATIONS
2008/04/16
Page 3
© GMV, 2008
INTRODUCTION
TO GMV
© GMV, 2008 Property of GMV
All rights reserved
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
© GMV, 2008
OUR OFFER
focus





FLIGHT DYNAMICS COLLOCATION:
ASSESSMENT AND OPERATIONS
2008/04/16
Page 6
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
© GMV, 2008
INTRODUCTION
TO focusSuite
© GMV, 2008 Property of GMV
All rights reserved
FLIGHT DYNAMICS: focusSuite PRODUCT
LINE
focus
SUITE
• 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)
FLIGHT DYNAMICS COLLOCATION:
ASSESSMENT AND OPERATIONS
2008/04/16
Page 8
© GMV, 2008
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
© GMV, 2008
focusSuite: ARCHITECTURE
GUI
Autofocus
External
App.

– 1st Tier: Presentation (clients)
– 2nd Tier: Process management
– 3rd Tier: Data management / Computation.
Normally includes legacy code based on
reliable flight dynamics algorithms
focusAPI
Process Manager
Data
Manager
focusSuite
Modules
Event
Manager

focusGEO focusLEO
Modules Modules
COLLOC
INICOL
FLIGHT DYNAMICS COLLOCATION:
ASSESSMENT AND OPERATIONS
focusCn
Modules
CLOSEAP
2008/04/16
Three-tier architecture, to promote
flexibility and modularity, allow
distribution and scalability:
Advanced API for interaction with Process
Manager
– Operator Manual Access (GUI)
– Automatic Procedures (Autofocus)
– External Applications (including SOA)
MATOOL
Page 10
© GMV, 2008
INTRODUCTION
TO FLIGHT
DYNAMICS AND
COLLOCATION
© GMV, 2008 Property of GMV
All rights reserved
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
© GMV, 2008
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
© GMV, 2008
COLLOCATION STRATEGIES:
Longitude Separation


Complete Longitude Separation
Partial Longitude Separation
OR
FLIGHT DYNAMICS COLLOCATION:
ASSESSMENT AND OPERATIONS
2008/04/16
Page 14
© GMV, 2008
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
© GMV, 2008
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
© GMV, 2008
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
© GMV, 2008
COLLOCATION
ASSESSMENT:
MATOOL
© GMV, 2008 Property of GMV
All rights reserved
WHAT IS MATOOL?
MATOOL is a station keeping and collocation analysis tool for
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
© GMV, 2008
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
© GMV, 2008
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
© GMV, 2008
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
© GMV, 2008
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
© GMV, 2008
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
© GMV, 2008
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
© GMV, 2008
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
© GMV, 2008
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
© GMV, 2008
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
© GMV, 2008
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
© GMV, 2008
COLLOCATION
OPERATIONS:
COLLOC
INICOL
CLOSEAP
© GMV, 2008 Property of GMV
All rights reserved
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
© GMV, 2008
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
FLIGHT DYNAMICS COLLOCATION:
ASSESSMENT AND OPERATIONS
2008/04/16
Page 33
© GMV, 2008
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
© GMV, 2008
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
CLOSEAP: CLOSE APPROACH PREDICTION

Automatic processing

Phased approach
focusCloseAp
LEVEL 1: BOX
LEVEL 2: SPHERE
LEVEL 3: ELLIPSOID
© GMV, 2008
CLOSEAP: CLOSE APPROACH PREDICTION
Output: Plots
• Separation plots between satellite and tracked objects
• Orbit plots showing evolution of satellite and tracked objects
• Avoidance manoeuvre
© GMV, 2008
OPERATIONAL COLLOCATION
EXPERIENCE
 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
© GMV, 2008
LESSONS
LEARNED
© GMV, 2008 Property of GMV
All rights reserved
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
© GMV, 2008
Thank you
© GMV, 2008 Property of GMV
All rights reserved