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  • Applied Geomagnetics for Attitude Determination Experiment (AGADE)

    Paper number



    Mr. Sebastian M. Ernst, Germany



    The Applied Geomagnetics for Attitude Determination Experiment (AGADE) aims
    for analysing and comparing a set of different commercial of-the-shelf small 3-axis
    magnetometer assemblies as well as data analysis methods. The COTS magnetometers
    are launched together with a high precision magnetometer on-board a ballistic rocket.
    After the the flight, the resulting data is being used for evaluating ideas of advanced onboard
    magnetic field data analysis software, which could be used in pico satellites'
    attitude determination systems as well as in an experimental orbit determination
    system based on pattern recognition algorithms.
    The experiment's proposal was submitted to the German Aerospace Center (DLR)
    within the REXUS programme on January 6th 2008. In the end of April 2008 the
    experiment was finally chosen to fly on-board REXUS 6, which was launched on
    March 12th 2009. A detailed report is expected to be released by the end of June 2009.
    Finally, the experiment's set-up was developed by about nine students from the
    Freiberg University of Mining and Technology (TU Bergakademie Freiberg) and the
    Dresden University of Technology (TU Dresden) studying Geophysics, Electronics
    Engineering, Computer Science, Mechanical Engineering and Aerospace Engineering.
    My field of interest
    With the decreasing size of electrical devices and computers over the past years it has
    become possible to decrease the size of satellites as well. The standard allowing the
    smallest satellites is currently the cubesat standard with a limited mass of only one
    kilogram. This development caused the need for smaller ADSs. One possibility to
    determine a spacecraft's attitude is to use a known magnetic field such as the earth's one
    together with a reference model of it and to compare the determined field's orientation
    with the reference model's.
    Magnetometers are a typical payload for scientific satellites. If research is conduct on a
    celestial body its magnetic field is interesting almost every time. But in these cases the
    magnetometers are the payload itself or part if it. Compared to an ADS, the major
    difference is that a payload has an higher priority, its low mass is not as important as it
    is for subsystems around just fulfilling their basic tasks. Here the very small
    magnetometers become a topic of interest. If their results would be good enough it
    would be possible to build simple, small and lightweight ADSs. In fact this idea is not
    new and these days such small magnetometers are in use on a couple of small satellites,
    some of them build according to the cubesat standard. To the best of my knowledge
    the only reliable, freely available studies about these sensors' accuracy and behaviour in
    space are results of computer based simulations. In most cases an accuracy of 5 to 10
    degree for attitude determination was reported for such sensors.
    Traditionally, the IGRF is simply used as a reference for this kind of measurements.
    An analysis of influences disturbing the measurements is sometimes not even
    considered. So, as a student of Geophysics, I found some kind of a vacant topic by
    applying knowledge from traditional exploration Geophysics, when I joined STARD.
    It is working on the SOMP cubesat. Later, my work on its ADS basically led me to the
    formation of the AGAD experiment.
    In case of AGADE I am working on data analysis, which means an detailed local
    magnetic field model of the rocket's flight path as well as an detailed model of the field
    disturbances caused by the rocket and its components. This analysis should lead to an
    conclusion of how far it is possible to go with such types of ADSs if there would be a
    much better reference.
    A further idea is to use the magnetic field sensors already included in ADCs to
    determine a satellite's orbit. This is possible due to the specific shape of the earth's
    magnetic field. First simulations have shown, that this idea basically works – based on
    data collected over one low earth orbit – using some kind of pattern recognition and
    the IGRF as a reference. I am planing to conduct further research on this issue by using
    the gained knowledge of the sensor's data's characteristics.
    Abstract document


    Manuscript document

    IAC-09.E2.1.7.pdf (🔒 authorized access only).

    To get the manuscript, please contact IAF Secretariat.