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Fifth European Conference on Space Debris

30 March - 2 April 2009
ESA/ESOC
Darmstadt, Germany


Classification and characterization of GEO population based on results of the ISON observations

V.Agapov, I.Molotov, Z.Khutorovsky, V. Titenko
 
Russian Academy of Sciences
Keldysh Institute of Applied Mathematics

Paper Presented at the 5th European Space Debris Conference,
Darmstadt Germany, March 30 - April 2 2009


International scientific optical network

Legend:
Green circles ISON observatory working in the project during few years already.
Blue circles ISON observatories working first year only.
Yellow circles ISON observatories where preparatory work are carried out.
Red circles observatories foreign partners of the ISON.
Orange circles observatories Russian partners of the ISON.

Main results obtained in 2005-2008

OPERATIONAL CAPABILITIES
  • Global GEO coverage capability is achieved that is important for continuous studying of the situation in that region
  • Since Jun 2007 wide GEO survey mode is implemented for longitudes 31.5W to 90E in a zone 16 with respect to the true GEO ring. Partial GEO survey mode is implemented for other longitudes

DISCOVERIES AND OVERALL AMOUNT OF DATA
  • Overall number of obtained measurements exceeded 950000
  • Number of continuously tracked objects in GEO - 1428, including 152 unknown bright ones (brighter than 15m)
  • 439 faint (fainter than 15m) GEO and GTO objects are discovered in GEO region surveys during the last 3 years, including objects with high AMR. Of this number 203 GEO objects are tracked continuously.
  • Thus population of tracked objects in GEO region is increased more than 35 per cent. New discoveries continues to happen in every survey.

ORBITAL EVENTS ANALYSIS
  • Unexpected changes in orbital motion of old GEO objects are revealed. Cause of those changes is not yet understood but in any case they can not be explained by natural forces like gravity or solar radiation pressure
  • Large amount of observation is collected that makes possible to perform accurate analysis of the peculiarities of controlled motion of the spacecraft belonging to different owners but located in the vicinity of the same GEO position
  • Some of discovered objects are clearly identified with operational fragments (usually not announced by operators) released during initial operations of the spacecrafts DSP, Fenyung-2D, MSG etc.

DATA PUBLICATION
  • orbital data for brighter objects are publishing annually in ESOC Classification of Geosynchronous Objects (the latest one Issue 11, Feb 2009)
  • results for GEO debris are publishing monthly by KIAM in High Geocentric Orbit Space Debris Circular.

Known GEO Population

  • Spacecraft 869
    • 339 are controlled
  • Upper stages 256
    • more than 15 different types
  • Fragments 303
    • only 20 are officially catalogued still

Distribution of 1434 GEO objects by period and inclination

Distribution of 1434 GEO objects by RAAN and inclination

10 years of orbital plane evolution for object 95177

10 years of orbital plane evolution for object 95177

Discovered space debris population characteristics

Distribution of average brightness for 434 fragments

Distribution of average AMR value for 211 fragments

Operational GEO objects orbital motion characterization

New classification of orbits for GEO operational satellites is proposed based on analysis of obtained data.

Following classes of satellites are observed:
  • C1 maintaining longitude and near-zero inclination
  • C2 maintaining longitude only
  • C3 maintaining longitude and non-zero inclination
  • C4 maintaining non 'true GEO' period and near-zero inclination while remaining in GEO protected region
  • C5 making manoeuvres on non 'true GEO' period orbit (including graveyard one) while remaining in defined GEO region

Each class can be divided into two subclasses:
  • orbits with eccentricity less than 0.001
  • orbits with eccentricity between 0.001 and 0.15

Object 27380 INTELSAT 904 (C1 type of orbital motion)

Object 95151 (C2 type of orbital motion)

Object 95162 (C3 type of orbital motion)

Object 95010 (C4 type of orbital motion)

Orbital events characterization for GEO region

  • Strange non-evolutionary changes are discovered for several old GEO objects
  • Object 1997-070A (old spacecraft Koupon) unexpectedly changed the direction of the drift on Jun 11, 2007 when it was near 90.82E (drift rate changed on 0.16 /day). Surprisingly it remained on libration orbit
  • Object 1993-013A (old spacecraft Raduga) showed minor non-evolutionary changes in it's drift rate in Apr and Sep 2007. The reason of the changes is unclear.

Koupon orbit change on Jun 11, 2007

Conclusions

  • New level of quality of GEO region research is achieved: full GEO arc coverage is established, regular wide surveys are carried out, for the first time our knowledge of true GEO population of objects brighter than 15m is complete and presented for public.
  • Several hundreds of earlier unknown objects discovered in GEO region are presenting clear indication of lack of our knowledge of true high orbits population. Number of discovered new high altitude fragments continues to grow so the research should be expanded in order to obtain as complete information as possible on potentially dangerous objects crossing orbits of operational GEO spacecraft.
  • Obtained information can be used for spaceflight safety and traffic management tasks on GEO thanks to more complete set of covered objects (35%), much higher accuracy and overall reliability comparing other existing public sources

3 2009


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