1 1 briefing for aiaa sostc workshop april 2011 tobias nassif, director sda

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Briefing for AIAA SOSTC WorkshopApril 2011

Tobias Nassif, Director SDA


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


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


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


Growth of Objects in Space


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


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


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


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


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


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


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


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


RFI Geolocation Sample Case

TLE-vs-TLETLE-vs-SDASDA-vs-SDA

10° Longitude Separation


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


Space Population Perigee-vs-Apogee Distribution

LEO: GEO:


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!


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


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


Semi-Major Axis Reveals NCT Discontinuities…


“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


Discontinuities Match Conjunctions…


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


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

1 1 briefing for aiaa sostc workshop april 2011 tobias nassif, director sda

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