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Improved Conjunction Analysis via Collaborative SSA

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Improved Conjunction Analysis via Collaborative SSA T.S. Kelso, D. Vallado (CSSI) J. Chan, B. Buckwalter (Intelsat) – PowerPoint PPT presentation

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Title: Improved Conjunction Analysis via Collaborative SSA


1
Improved Conjunction Analysis via Collaborative
SSA
  • T.S. Kelso, D. Vallado (CSSI) J. Chan, B.
    Buckwalter (Intelsat)

2
Overview
  • Motivation
  • Background
  • Proposed Solution
  • Validation
  • SOCRATES-GEO
  • Future Enhancements
  • Summary Conclusions

3
Motivation
  • Recent events emphasize need for improved SSA for
    conjunction analysis
  • Chinese ASAT test (2007 Jan 11)
  • 2,529 pieces cataloged to date (only 49 decayed)
  • USA 193 intercept (2008 Feb 21)
  • 174 pieces cataloged (1 still on orbit)
  • ISS maneuver to avoid Cosmos 2421 debris (2008
    Aug)
  • 509 pieces cataloged (48 still on orbit)
  • Iridium 33/Cosmos 2251 collision (2009 Feb 10)
  • 999 pieces cataloged to date (822 public) only 6
    decayed
  • ISS evacuation (2009 Mar 12), move (2009 Mar 22)

4
SATCAT Growth 1957 to Present
5
Motivation at GEO
  • Geostationary orbit (GEO) is a limited resource
  • More satellites more conjunctions
  • 30 payloads launched in 2008
  • gt369 active payloads
  • Implications of a collision are significant
  • Potential loss of colliding satellites and
    associated revenues
  • Increase in debris, putting other satellites at
    risk

6
Background
  • Conjunction analysis needs full-catalog orbital
    data
  • TLEs are currently the only such source
  • Low accuracy results in high false-alarm rate
  • Current system limited to non-cooperative
    tracking
  • US SSN uses combination of radar and optical
    resources
  • Operational satellites most difficult to track
    due to maneuvers
  • Maneuvers typically not known ahead of time
  • Delays in detecting maneuvers can result in poor
    accuracy or even lost satellites
  • Requires more SSA resources to maintain orbits

7
Proposed Solution
  • Satellite operators already maintain orbits
  • Active ranging, GPS can be very accurate
  • Develop Data Center to collect operator data
  • Use operator data to improve conjunction analysis
  • Provide analysis/data to all contributors
  • Current Data Center participation (13335)
  • Intelsat (556), Inmarsat (11), EchoStar (6), SES
    (411 Astra, New Skies, Americom), NOAA (4),
    Star One (6), Telesat (618), EUMETSAT (4)
  • Pending IAI (3), Paradigm (7)

8
Analysis of Orbital Data Sources
  • Many sources of operator orbital data
  • Direct from satellite operator (Data Center)
  • Public sources
  • GPS (almanacs, precise ephemerides)
  • GLONASS (precise ephemerides)
  • Intelsat (11-parameter data, ephemerides)
  • NOAA, EUMETSAT (state vectors)
  • Challenges
  • User-defined data formats
  • Variety of coordinate frames time systems used

9
Supplemental TLEs
  • Uses public orbital data
  • GPS almanacs
  • GLONASS precise ephemerides
  • Intelsat 11-parameter data
  • Import data into STK to generate ephemerides
  • Generate TLE from ephemerides
  • Allows users to see benefit
  • Test cases with supporting data
  • Overcomes limitations in most orbital software
    that can only handle TLEs/SGP4

10
GPS Almanacs vs. TLEs
Mean 1.292 km Max 3.073 km
Mean 7.544 km Max 32.449 km
11
GPS Supplemental TLEs
Mean 0.872 km Max 2.366 km
Mean 7.544 km Max 32.449 km
12
GLONASS Supplemental TLEs
Mean 0.201 km Max 0.539 km
Mean 3.301 km Max 9.388 km
13
Case Study Intelsat Data Comparisons
Owner ephemerides AFSPC TLEs
14
Case Study ASTRA 1 Cluster
  • Open source image of cluster
  • http//www.foton.co.za/assa_imaging.htm
  • Taken 2009 Jan 21 at 202111 UTC
  • Site location 33.94058 S, 18.51294 E, 10 m
  • Pinelands, a suburb of Cape Town, South Africa
  • Telescope 6-inch, f/2.7 reflector
  • FOV 54.7 x 40.2 arcminutes
  • Compared SES ephemerides and latest TLEs

15
SES Ephemerides Hipparcos Stars AFSPC TLEs
16
SES Ephemerides Hipparcos Stars AFSPC TLEs
17
SES Ephemerides Hipparcos Stars AFSPC TLEs
18
SES Ephemerides Hipparcos Stars AFSPC TLEs
1H to _1H 71 km
19
SES Ephemerides Hipparcos Stars AFSPC TLEs
20
SOCRATES-GEO
  • Extension of SOCRATES
  • Satellite Orbital Conjunction Reports Assessing
    Threatening Encounters in Space
  • Running since 2004 May
  • Looks for any time anything gets within 5 km of
    payload
  • 2,959 payloads vs. 12,817 total objects (as of
    2009 Mar 31)
  • 13,979 conjunctions (2009 Mar 31 7 days)
  • Runs automatically twice per day
  • Generates standard reports available via the
    Internet
  • Uses only TLEs
  • Limited accuracy due to non-cooperative tracking
  • Does not account for maneuvers well
  • US SSN tracks over 19,000 objects

21
SOCRATES-GEO Today
  • Includes all objects which pass 250 km of GEO
  • 752 payloads vs. 1,334 total objects (as of 2009
    Mar 31)
  • 1,094 conjunctions within 50 km (2009 Mar 31 7
    days)
  • Uses best data sources available
  • Generates standard reports
  • Runs in under 15 minutes on standard PC
  • Provides links to standard (OEM) orbital data
  • Allows user-defined notification criteria
  • Automatically sends notification
  • Web access to latest data via secure system

22
Data sources
Data preparation
Owner ephemeris
Convert to standard format
Public orbital data
Generate ephemerides
Select GEO data
TLE data
Produce enhanced TLEs
23
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24
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25
Future Enhancements
  • Process new data as received
  • User defines notification interval
  • Parallel analysis tool for maneuver planning
  • Improved data status page
  • Data type, age, and quality
  • Direct contact information for operational
    satellites
  • Enhanced graphs, reports, visualization
  • Customizable tool kits

26
Summary Conclusions
  • Bottom line
  • Technical solution is easy
  • Biggest obstacle
  • Data sharing policies
  • Other issues
  • Organization
  • Resources Funding
  • Together we can work today to mitigate risk

27
Questions?
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