Post on 13-Jan-2016
transcript
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Briefing for AIAA SOSTC WorkshopApril 2011
Tobias Nassif, Director SDA
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What is the Space Data Association?
A formal association of satellite operators, established in the Isle of Man which will support the controlled, reliable and efficient sharing of data critical to the safety and integrity of satellite operations
– Legal framework to protect the sharing of data– Physical systems to make data sharing efficient, secure and
reliable reducing operators workload and mitigating risks– Technical support to ensure operations integrity– Shared costs and ‘not-for-profit’ ethos to reduce individual costs
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SDA Charter
Seek and facilitate improvements in the safety and integrity of satellite operations through wider and improved coordination between satellite operators
Seek and facilitate improved management of the shared resources of the Space Environment and the RF Spectrum
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Why was the SDA created?
To improve the accuracy of collision avoidance predictions– Expand satellite operator participation– Adopt best practices across industry– Provide necessary framework for full operations (legal, technical)– Address operational issues with current cross-industry conjunction
coordination
To take advantage of opportunities for other data sharing– RFI mitigation, including data for RFI geolocation– Company contacts– General operations data sharing
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Growth of Objects in Space
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Who can join the SDA?
The SDA will be run by and for the benefit of satellite operators and the integrity of their operations
– Members should be the owners or responsible for the control and orbit operations of in-orbit satellites
– Membership is open to all satellite operators in all orbital regimes
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Why Join the SDA?
Members will receive secure, reliable and immediate access to accurate information that can help improve their operations– Conjunction assessments– Data for RF Interference analysis and geolocation– Contact information
Ensure the following of best practices and mitigating operational risks
Reduce workload– Automated data conversions for conjunction– Information readily available– Focus on real issues identified by reliable systems
Ensure the use of shared data is controlled and legally protected Minimize the cost for these critical operations
SDA membership will improve the integrity of its members’ satellite operations and that of all satellite operators
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SDC – Three Key Mission Areas
Collision Avoidance (CA) monitoring, maneuver planning & Flight Safety
Radio Frequency Interference mitigation & geolocation support
Authoritative contact information (operations center & POCs) for SDA Member satellites
Initial Operating Capability (IOC) commenced 27 July 2010
Final Operational Capability (FOC) expected Q1 2011
SDC currently performing Collision Avoidance monitoring for 197 satellites from 13 GEO
operators and 114 satellites from 7 LEO operators
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Key Components of a Reliable and Robust SDC Providing Meaningful Space Situational Awareness (SSA):Clear, comprehensive key SSA mission areas Screening every two hours for one-week duration
Definitive ephemeris, maneuvers & physical properties
Accurate data rectification and Ephemeris Quality Control Process
Definitive SDA Member RF characteristics (geolocation, ASI)
Integrated, automated CA And RFI using all-inclusive, latest data from best-available sources
Centralized, authoritative POC database Data Trending for CA & RFI Repeat Offender ID & SSA Research
Addresses known Non-Cooperative Tracking (NCT) shortcomings (e.g., no powered flight, maneuver corruption of orbit solution, cross-tagging)
Comprehensive RFI mitigation capabilities (RFI geolocation support, RFI analyses and near-real-time RFI alerts)
Operated by Technical Subject Matter Experts (CA & RFI, Reference Frames, OD, Space Population Evolution & Distribution, Fragmentation, Maneuver Reconstruction & Detection, Astrodynamics, Ephemeris Rqmts For Accurate SSA)
Relies upon ISO, CCSDS Intl Stds & Best Practices (Orbit Data Messages, Reference Frames, Orbit Determination and Orbit Lifetime)
SDC Database-Driven Analysis Framework Supporting both Web Services interfaces + Accessible User Interface
Geographically-diverse, secure, high-availability computing framework with extensive data protection
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SDA’s Role in Industry Issues
Operational Challenges Causes
TypicalMitigationApproach
SDA’s role inAddressing Ops
Challenges
Mitigating Collision Risk
- Space is increasingly congested
- ITU doesn’t regulate physical space
- No integrated CA screening with all best-available data
Services such as:- Socrates-GEO- Non-Cooperative Tracking
agencies (NCTs)- Commercial collision
avoidance services
SDA Conjunction Assessment Service
Mitigating RF Interference
RFI Increasing; Sources:- Human error (95%)
- ASI - Cross-pol / Pwr issues
- Terrestrial Rx Issues (1%)
- Equipment fault (4%)- Deliberate (tiny %)
Operator actions such as:- Signal analysis- Carrier record checks- Customer checks- Alerts to other operators- Predictive RFI analyses
(GEO drifters, LEO)- Geolocation (if available)
SDA RFI Service and Alerts
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SDC Planned CA Process Flow
Members contribute and dynamically maintain proprietary satellite maneuver plans, dimensions, status
Members define vehicle-specific conjunction and Neighborhood Watch criteria
Satellite ephemerides are automatically updated by all SDA members
Non-Cooperative Radar and Optical Tracker-based orbit vectors and/or ephemeris
Close Approach Alert notification sent to Members
Optional information accumulated for collision threat trending and long-term threat mitigation
Rectified data and STK analysis scenarios facilitate maneuver avoidance planning & optimization
Data provided on upcoming conjunctions, and contact information to conduct collision threat mitigation
SDC
Data stored in common format
System allows faster investigation of CA events, enabling responsive and accurate threat mitigation
Independent SDC vector comparison & OD verification
SDA Member-unique ephemeris converter created & tested
Conjunctions Analyzed
Conjunctions Alerts Sent
Neighborhood Watch Results Sent
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SDC Planned RFI Process Flow
Members contribute and dynamically maintain proprietary RF data: Freq plan; polarization; translation freqs; antenna patterns, Rx & Tx chars, beam coverage
Members contribute data on Reference Emitters/Calibrators
Satellite ephemerides are automatically updated by all SDA members
Members detect an RFI event and report the details to the SDC
RFI Alert notification sent to Members
Optional information provided to third parties for geolocation or other services
Geolocation solution sets generated and sent to Member in format for geolocation system
Database queried for most likely region, satellite(s), and contact information to investigate potential interference source
SDC
Frequency bands and beam coverages searched for suitable adjacent satellites for geolocation measurements
Data stored in common format
System allows faster investigation of RFI events, improving service quality and creating more efficient operations
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SDA and Geolocation
Without SDA– Multiple phone calls required– Hours/days required to locate viable
solution set and data– Data formats = anyone’s guess
With SDA– Solution sets immediately available– All necessary data centralized and in
consistent format– Better data = more accurate results
Geolocation error reduced two orders of magnitude using SDA-on-SDA quality ephemeris
SDA enables faster, more accurate geolocation results
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RFI Geolocation Sample Case
TLE-vs-TLETLE-vs-SDASDA-vs-SDA
10° Longitude Separation
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Potential Future SDA RFI Capabilities
Collect, process, store & disseminate interference details, analyses & solution sets from all sources to enable appropriate investigation, notification and enforcement– both within SDA and with approved external entities
Coordinate data with and for SDA RF experts to identify, analyze, locate, attribute and mitigate interference sources
Develop & maintain RFI mitigation capabilities, procedures and techniques to ensure continuity of operations
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Space Population Perigee-vs-Apogee Distribution
LEO: GEO:
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Space Population and Risk Spatial density of space objects at GEO
higher than at LEO– “Constrained” GEO inclination = contributing factor– Statistics less of interest than actual collision threats!
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Why Non-Cooperative Tracking (NCT) is not enough…
Radar & optical tracking good for debris data but may have errors for active satellites
NCTs fit orbit across maneuver(s)– Low thrust, long duration burns common at GEO– Degrades OD sol’n accuracy regardless of orbit theory
“Cross-tagging”– Observations associated with wrong satellite
i.e., multiple satellites in sensor field of view “Cross-tagging most likely when you need most accuracy” Caused / compounded by maneuvers during tracking
– NCT obs. association independent of OD/theory
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Cross-tagging and System Errors
Galaxy-15 anomaly caused westward drift with no maneuvers from April – December 2010– G15 WAAS intact; orbital position well understood by operator
but not in public catalog– Great opportunity to study public data-derived performance
Large cross-tag discontinuity observed 13 Aug– Readily identified as G15/G18 conjunction
Many other such discontinuities observed Collision risk was never an issue because SDA
Members were sharing ephemerides with the SDC
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Semi-Major Axis Reveals NCT Discontinuities…
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“TLE Detective” Identifies Cross-tags
For G15 case, using 2.5σ filter with recursive excision, found that 52 out of 348 (15%) of NCT-derived positional products contain cross-tag or equivalent accuracy degradations
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Discontinuities Match Conjunctions…
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The Next Steps
The SDC has commenced initial operations
Final Operational Capability scheduled Q1 2011
The SDA is promoting its services and encouraging all satellite operators to become Members
Members can become involved with future requirements, development and testing of the CA and RFI functionality
The SDC is expected to evolve and become a major operational system for satellite operators, for safety of flight, and RFI mitigation
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Additional NCT Cross-tagging
IS-6B IS-3R IS-11
IS-6B IS-3RIS-11
Owner ephemeridesPublic Data
43.25° W 43.00° W 42.75° W
Spacing = 184 km
2008 Comparison