Two different Earth-pointing missions dealing with attitude control and dynamics changes illustrate concerns with correlated error sources and coupled effects that can occur. On the OrbView-2 (OV-2) spacecraft, the assumption of a nearly-inertially-fixed momentum axis was called into question when a residual dipole bias apparently changed magnitude. The possibility that alignment adjustments and/or sensor calibration errors may compensate for actual motions of the spacecraft is discussed, and uncertainties in the dynamics are considered. Particular consideration is given to basic orbit frequency and twice orbit frequency effects and their high correlation over the short science observation data span. On the Tropical Rainfall Measuring Mission (TRMM) spacecraft, the switch to a contingency Kalman filter control mode created changes in the pointing error patterns. Results from independent checks on the TRMM attitude using science instrument data are reported, and bias shifts and error correlations are discussed. Various orbit frequency effects are common with the flight geometry for Earth pointing instruments. In both dual-spin momentum stabilized spacecraft (like OV-2) and three axis stabilized spacecraft with gyros (like TRMM under Kalman filter control), changes in the initial attitude state propagate into orbit frequency variations in attitude and some sensor measurements. At the same time, orbit frequency measurement effects can arise from dynamics assumptions, environment variations, attitude sensor calibrations, or ephemeris errors. Also, constant environment torques for dual spin spacecraft have similar effects to gyro biases on three axis stabilized spacecraft, effectively shifting the one-revolution-per-orbit (1-RPO) body rotation axis. Highly correlated effects can create a risk for estimation errors particularly when a mission switches an operating mode or changes its normal flight environment. Some error effects will not be obvious from attitude sensor measurement residuals, so some independent checks using imaging sensors are essential and derived science instrument attitude measurements can prove quite valuable in assessing the attitude accuracy.


    Zugriff

    Zugriff über TIB

    Verfügbarkeit in meiner Bibliothek prüfen


    Exportieren, teilen und zitieren



    Titel :

    Correlated Errors in Earth Pointing Missions


    Beteiligte:
    S. Bilanow (Autor:in) / F. S. Patt (Autor:in)

    Erscheinungsdatum :

    2005


    Format / Umfang :

    15 pages


    Medientyp :

    Report


    Format :

    Keine Angabe


    Sprache :

    Englisch




    Correlated Errors in Earth Pointing Missions

    Steve Bilanow / Frederick S Patt | NTRS | 2005


    Advanced Pointing Control Techniques for Small Satellite Earth Observation Missions

    Peri, Leonardo / De Maeyer, Jeroen / De Munter, Wim et al. | AIAA | 2025


    A Miniaturized Pointing Mount for Spacelab Missions

    C. G. Fritz / T. Howell / P. D. Nicaise et al. | NTIS | 1975


    A miniaturized pointing mount for Spacelab missions

    Fritz, C. G. / Howell, T., Jr. / Nicaise, P. D. et al. | NTRS | 1975


    Earth-Pointing Recovery

    M. P. Ramachandran | AIAA | 2006