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High power large aperture radar measurements of the Iridium-Cosmos collision

Image: ESA. High power large aperture radar measurements of the Iridium-Cosmos collision. J. Vierinen , J. Markkanen and H. Krag. European Incoherent SCATter radar(EISCAT). UHF: Tri-static, 32 m, 930 MHz, 2 MW,12.5% duty-cycle ESR: Bi-static, 32 & 42 m, 500 MHz, 1 MW 25% duty

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High power large aperture radar measurements of the Iridium-Cosmos collision

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  1. Image: ESA High power large aperture radar measurements of the Iridium-Cosmos collision • J. Vierinen, J. Markkanen and H. Krag

  2. European Incoherent SCATter radar(EISCAT) • UHF: Tri-static, 32 m, 930 MHz, 2 MW,12.5% duty-cycle • ESR: Bi-static, 32 & 42 m, 500 MHz, 1 MW 25% duty • VHF: mono-static, 120x40 m, 224 MHz, 3 MW, 12.5 % About 10 years of space debris involvement.

  3. ESR UHF & VHF

  4. Iridium - Cosmos collision • On 10.2. 2009, 16:56 UT, Iridium 33 and Cosmos 2251 satellites collided over Siberia at 789 km with a relative speed of approximately 11.7 km/s. Video courtesy of Analytical Graphics, Inc. (www.agi.com).

  5. Analysis procedure • Fourier series match function model • Combining raw detections to form line-of-sight trajectories and radar cross-section estimates • Maximum a posteriori estimate using full statistical model

  6. 1. Fourier series match function • Target rotation and numerical approximations cause spreading of target backscatter spectrum • Target backscatter very narrow band • Maximum likelihood estimate for Doppler, and and backscatter power. • Corresponds to coherent integration

  7. 2. Combining detections • Use a restricted grid search to find target trajectories amongst the sufficiently strong and separated detections within the coherent integration blocks

  8. 3. Full statistical model • Model radial trajectory using e.g., a spline • Estimate parameters using e.g., Markov Chain Monte-Carlo • Use parameters obtained from the detection step as prior information

  9. Moving point model

  10. Collision related measurements: • Campaign measurements, December 2008 • UHF 14.2. 2009 (spade) • ESR 19.2. 2009 (steffe) • UHF 12-15.5. 2009 (beata, spade) • UHF 24.6. 2009 (manda)

  11. Spade experiment • D-, E- and F-region ionospheric measurement • 16000 km gapless Space Debris, meteor head echos

  12. Magnetic field aligned Tromsø 14.2.2009

  13. Kosmos Iridium Tromsø 14.2.2009

  14. Magnetic field aligned Steffe Svalbard 19.2. 2009

  15. Magnetic field aligned Beata Tromsø 12.5.2009

  16. Kosmos Iridium ? Magnetic field aligned Beata Tromsø 13.5.2009

  17. Tri-static debris measurement

  18. Tri-static (eastward) Spade Tromsø 14.5.2009

  19. Kosmos ? Iridium ? Tri-static (eastward) Spade Tromsø 14.5.2009

  20. Tri-static (eastward) Spade Kiruna 14.5.2009

  21. Tri-static (eastward) Spade Sodankylä 14.5.2009

  22. Debris model • ESA MASTER model (Klinkrad 1997) • Can be used to simulate debris detected using radars and telescopes (Krag 2000) • Not exact trajectories, stochastic model • Used e.g., to estimate collision probability with a spacecraft • EISCAT measurements can be used to validate the model

  23. ?

  24. Model predicts less spread

  25. Model predicts less debris than we observe

  26. Bi-static and tri-static measurement allows full orbital element determination Currently smooth tracking impossible Stepped approach works with the current system Orbital element measurement

  27. Trial run RMS error 75 m

  28. Conclusions • Due to location and sensitivity, EISCAT offers a unique set of radars for small space object studies (2 cm at 1000 km) • We have observed the Iridium-Kosmos debris with EISCAT radars • New multi-purpose experiments (plasma parameters, space debris, meteors) • Higher estimation accuracy possible with higher computational cost • We’re moving towards tri-static measurements

  29. Thank you... EISCAT 3D

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