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Improved Orbit Error Budget Analysis for Satellite Missions

This report revises the orbit error budget analysis for satellite missions, detailing contributors like static gravity, tide models, and solar radiation pressure. The study evaluates the impact of variable gravity, station/data errors, and geocenter motion on orbit determination noise. Results show lower error margins and better characterization compared to previous missions. Key topics include atmospheric gravity effects, differences in gravity models, and the influence of reference frames on orbit precision. The report assesses the effects of solar radiation pressure and station/data errors, providing crucial insights for future satellite missions.

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Improved Orbit Error Budget Analysis for Satellite Missions

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  1. POD/Geoid Splinter Summary OSTS Meeting, Hobart 2007

  2. POD reportRevised orbit error budget • Contributors to the orbit error budget have not changed since TOPEX/Poseidon • static gravity • tide models • variable gravity • solar radiation pressure • station / data errors • reference frame • geocenter motion • orbit determination noise • but they are now lower and better characterized

  3. Static Gravity • Differences between newer GRACE models are small • order 1 harmonics contribute largest GCEs

  4. Tide models

  5. Variable gravity

  6. Time-Varying Atmospheric Gravity • SLR residuals RMS globally reduced by ~1 mm when adding atmospheric gravity

  7. AOD1B SHDP GDR-B Impact on GCEs Mean Radial Difference relative to JPL06b in mm(averaged over cycles 22 to 99 = Aug 02 to Sep 04) • Atmospheric gravity reduces geographically correlated differences with JPL06b reduced dynamics orbits

  8. Grace-derived time-variable gravity to 20x20 (annual terms only) • Monthly solutions from KBRR data only • Fit mean, trend, & annual harmonic • 2 solutions: 1-yr & 3-yr data span Reference: ‘Monthly spherical harmonics gravity field solutions determined from GRACE inter-satellite data alone,’ Luthcke et al., Geophyscal Research Letters, 2006.

  9. POD Results for JASON 12.7 mm 12.2 mm 11.9 mm 11.5 mm .3219 mm/s .3185 mm/s .3185 mm/s .3181 mm/s 54.7 mm 54.6 mm 54.6 mm 54.3 mm RMS values of one arc per month of the obervations residuals after orbit adjustment

  10. Solar radiation pressure • There is evidence of small residual errors in both the scaled box-wing (GDR-B) and the UCL (JPL) model from L. Cerri

  11. Solar Radiation Pressure SRP is largest surface force acting on T/P and Jason-1 (T/P area-to-mass ratio is half that of Jason-1) Z variation due to 3% scale error in SRP model It is easily shown that a bias in the SRP model interacts with estimated empirical 1/rev parameters to create periodic Z-shift correlated with beta-prime from J. Ries

  12. Solar radiation pressure • GSFC’s attempt to rescale model at GSFC leads to mixed results from F. Lemoine

  13. Solar radiation pressure Z-shift induced by rescaling of SRP model not sufficient to explain Z offset between DORIS/SLR and GPS orbits

  14. Station / Data errors

  15. Jason DORIS SAA correction

  16. Jason DORIS SAA correction: Comparison of SLR/DORIS & SLR/Crossover Orbits ~ 0.9 mm oscillator jump at cycle 91

  17. Jason DORIS SAA correction

  18. Reference frame • ITRF2005 • results indicate that ITRF2005 corrects a drift in the centering of ITRF2000 • Z drifts between the various orbits are significantly reduced with ITRF2005 • transition from ITRF2000 to ITRF2005 will induce a shift in Z

  19. Evaluation of new Jason orbits based on ITRF2005

  20. Evaluation of new TOPEX orbits based on ITRF2005

  21. TOPEX Radial Orbit Difference Trends (ITRF2005 – GDR (CSR95)) Geographically correlated error (GGM02C-JGM3) Annual signal amplitude (TVG annual – none)

  22. Long-term Orbit Error and the Terrestrial Reference Frame (TRF) Jason (and TOPEX) radial orbit differences are driven by the difference in Z

  23. TOPEX Radial Orbit Difference Trend ITRF2005 – GDR (CSR95) Consequent error in estimated regional and global MSL trends

  24. Jason GSFC TRF orbit trends

  25. Jason TRF orbit trends – JPL GPS

  26. Geocenter motion

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