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COMMITTEE ON SPACE RESEARCH

37th COSPAR Scientific Assembly
Montreal, Canada , 13-20 July 2008


THE ISON INTERNATIONAL OBSERVATION NETWORK LATEST SCIENTIFIC ACHIEVEMENTS AND THE FUTURE WORKS

V.Agapov, I.Molotov, V.Titenko

Russian Academy of Sciences
Keldysh Institute of Applied Mathematics


The UN General Assembly Resolution 62/117 (1 February 2008)

The General Assembly,

Considering, that space debris is an issue of concern to all nations,

28. Considers that it is essential that Member States pay more attention to the problem of collisions of space objects, including those with nuclear power sources, with space debris, and other aspects of space debris, calls for the continuation of national research on this question, for the development of improved technology for the monitoring of space debris and for the compilation and dissemination of data on space debris, also considers that, to the extent possible, information thereon should be provided to the Scientific and Technical Subcommittee, and agrees that international cooperation is needed to expand appropriate and affordable strategies to minimize the impact of space debris on future space missions;

The ISON network

The International Scientific Optical Network (ISON) is continued to develop. In 2007-2008 the network was gradually improved both in the number of facilities and the quality of its output. New tasks have been added. As of the mid of 2008 the ISON network joins:
  • 18 scientific institutions in 9 states, including partners from ESOC, AIUB, astronomical organizations of Bolivia, Georgia, Moldova, Russia, Tajikistan, Ukraine, Uzbekistan
  • 16 observatories and observation facilities
  • 21 optical instruments
  • more than 50 observers and researchers
Project principal coordinator responsible for the formulation of the solving tasks, observation planning, collecting and analysis of the results is Keldysh Institute of Applied Mathematics of the Russian Academy of Sciences (KIAM RAS).

The ISON



Current capabilities and research directions

As of mid 2008 the ISON is capable to perform:
  • Selected objects observation across whole GEO-belt (360)
  • Near GEO-belt ( 2) surveys for the arc 130.3W 210.6E
  • GEO region wide surveys for the arc 30W 90E with the goal of discovery of all objects brighter than 16m
  • Uncatalogued GEO debris search (using different strategies, limiting magnitude 19m) and tracking (limiting magnitude 21m)
  • GTO and other HEO objects observations including faint space debris
  • Photometry of tracked objects
  • High altitude space debris physical properties study
  • Measurements, orbits and object properties database maintenance
  • Close encounters analysis
  • Improvement of the motion model using for data processing in part of non-gravity perturbations

Main results obtained in 2005-2008

  • Global GEO coverage capability is achieved that is important for continuous studying of space debris 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
  • Overall number of obtained measurements exceeded 650000
  • Number of continuously tracked objects in GEO and HEO - 1690, including 152 unknown bright GEO objects (brighter than 15m) orbital data for which publishes annually in ESOC Classification of Geosynchronous Objects (the last one Issue 10, Feb 2008) and 120 unknown bright HEO objects
  • 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 192 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.
  • Results are publishing monthly by KIAM in High Geocentric Orbit Space Debris Circular.
  • 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.

Discovered new bright GEO objects characteristics

Discovered space debris measurement statistics

Distribution of average brightness for 434 fragments

Distribution of average AMR value for 211 fragments

Distribution of inclination and RAAN for 432 fragments

Distribution of eccentricity and semimajor axis for 336 fragments

Distribution of perigee and apogee for 336 fragments

Orbital arcs (6-params orbit)

Orbit last update statistis

GEO and GEO-like object follow-up observation statistics

All known GEO objects population orbital characteristics

Different mechanisms are involved into GEO debris creation

Fragments in GEO region are discovered on different types of orbits both drifting and librating. That means there are different GEO debris creation processes:
  • for debris on libration orbits → separation with small relative velocity from the parent object (possible scenario low velocity collision, deterioration of outer surface under influence of the environment or low velocity operational fragment separation)
  • for debris on drifting orbits → high velocity separation from any object in GEO region (possible scenario fragmentation in explosion) or low velocity separation from objects moved to the graveyard orbit (possible scenario low velocity collision or deterioration of outer surface under influence of the environment)
Additional studies are required to understand the most probable scenario of GEO fragments creation and to develop recommendations how to avoid (if possible) new fragments generation in the future.

Orbital events characterization for GEO region

  • Analysis of orbital motion for each tracked object and discovering events resulting in non-evolutionary changes of orbit (manoeuvres etc.)
  • 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 region
    • C5 making manoeuvers on non 'true GEO' period orbit while remaining in 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
  • 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

LEO and HEO experimental observation results obtained in 2007-2008

  • Successful experiments on independent discovery and tracking of debris created in fragmentations of Briz-M upper stage (object #28944), Block of ullage motor (#25054) and Fengyun 1C (#25730) are carried out. Small aperture (22 cm) optical instrument is used.
  • 120 earlier unknown bright and more than 150 faint objects are observed on HEO orbits (mostly GTO and Molniya-type). All discovered bright objects are continuously tracking at present.

LEO objects observations with small aperture optics

Brightness distribution for object #30457 (average size 26 cm)

LEO and HEO objects observation

Typical brightness patterns for unknown HEO object 96071 and LEO object #16453

HEO objects observation

The ISON perspectives for 2009

  • > 30 telescopes with aperture from 15 cm to 2,6 m
  • Independent continuous tracking of all objects larger than 1 m in size and more than 90% of objects larger than 0.5 m in size along all GEO arc
  • Improved capability to detect and to track faint GEO and HEO objects with magnitude down to 21m
  • Monitoring of GTO, Molniya and other types of HEO and continuous tracking of more than 80% HEO objects larger than 1 m in size
  • Capability to carry out regular optical surveys of LEO
  • Publication of special information bulletin
  • Maintenance of the special public Internet-resource with updated orbital information on all tracked high altitude objects

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 and on HEO orbits are presented a 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 and HEO spacecrafts.
  • The regular process of discovering and continuous tracking of high orbit fragments is established (to the date more than 130000 obtained for nearly 450 such fragments)
  • Obtained information is publishing on a regular basis
  • The ISON network is developing intensively and will be capable soon to independently track all GEO and HEO objects brighter than 15th-16th magnitude as well as to accurately monitor LEO dangerous objects
  • The ISON is an open scientific structure and all nations are welcome to participate

26 2008

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