Neutral Density and Crosswind Determination from Arbitrarily Oriented Multiaxis Accelerometers on Satellites

Abstract

An iterative algorithm for determining density and crosswind from multiaxis accelerometer measurements on satellites is presented, which works independently of the orientation of the instrument in space. The performance of the algorithm is compared with previously published algorithms using simulated data for the challenging minisatellite payload. Without external error sources, the algorithm reduces rms density errors from 0.7 to 0.03% andrmswinderrorsfrom38to1 m=sinthistest.However,theeffectsoftheerrorsintheinstrumentcalibrationand the external models that are used in the density and wind retrieval are dominant for the challenging minisatellite payload. These lead to mostly systematic density errors of the order of 10–15%. The accuracy of the wind results whenusingthenewalgorithmisalmostfullydeterminedbythesensitivityofthecross-trackaccelerationcomponent to the calibration and radiation pressure modeling errors. The applicability of the iterative algorithm and the accuracyofits resultsaredemonstrated bypresenting challenging minisatellite payload datafromaperiodin which thesatellitewascommandedto flysidewaysandbycomparingthedensityandwindresultswiththosefromadjacent days for which the satellite was in its nominal attitude mode. These investigations result in recommendations for the design of future satellite accelerometer missions for thermosphere research.