Magnetic torquer induced disturbing signals within GRACE accelerometer data

authored by: Nadja Peterseim, Jakob Flury, Anja Schlicht
Abstract: The GRACE (Gravity Recovery And Climate Experiment) gravity field satellite mission was launched in 2002. Although many investigations have been carried out, not all disturbances and perturbations upon satellite instruments and sensors are resolved yet. In this work the issue of acceleration disturbances onboard of GRACE due to magnetic torquers is investigated and discussed. Each of the GRACE satellites is equipped with a three-axes capacitive accelerometer to measure non-gravitational forces acting on the spacecraft. We used 10 Hz Level 1a raw accelerometer data in order to determine the impact of electric current changes on the accelerometer. After reducing signals which are induced by highly dominating processes in the low frequency range, such as thermospheric drag and solar radiation pressure, which can easily be done by applying a high-pass filter, disturbing signals from onboard instruments such as thruster firing events or heater switch events need to be removed from the previously filtered data. Afterwards the spikes which are induced by the torquers can be very well observed. Spikes vary in amplitude with respect to an increasing or decreasing current used for magnetic torquers, and can be as large as 20 nm/s ² . Furthermore, we were able to set up a model for the spikes of each scenario with which we were able to compute model spike time series. With these time series the spikes can successfully be removed from the 10 Hz raw accelerometer data. Spectral analysis of the time series reveal that an influence onto gravity field determination due to these effects is very unlikely, but can theoretically not be excluded.
Organisation(s): Institute of Geodesy
External Organisation(s): Technical University of Munich (TUM)
Type: Article
Journal: Advances in space research
Volume: 49
Pages: 1388-1394
No. of pages: 7
ISSN: 0273-1177
Publication date: 01.05.2012
Publication status: Published
Peer reviewed: Yes
ASJC Scopus subject areas: Aerospace Engineering, Astronomy and Astrophysics, Geophysics, Atmospheric Science, Space and Planetary Science, Earth and Planetary Sciences(all)
Electronic version(s): https://doi.org/10.1016/j.asr.2012.02.013 (Access: Closed)
: Details in the research portal "Research@Leibniz University"

BibTeX

@article{01b2437696374e11a7c943e4f1b24215,
title = "Magnetic torquer induced disturbing signals within GRACE accelerometer data",
abstract = " The GRACE (Gravity Recovery And Climate Experiment) gravity field satellite mission was launched in 2002. Although many investigations have been carried out, not all disturbances and perturbations upon satellite instruments and sensors are resolved yet. In this work the issue of acceleration disturbances onboard of GRACE due to magnetic torquers is investigated and discussed. Each of the GRACE satellites is equipped with a three-axes capacitive accelerometer to measure non-gravitational forces acting on the spacecraft. We used 10 Hz Level 1a raw accelerometer data in order to determine the impact of electric current changes on the accelerometer. After reducing signals which are induced by highly dominating processes in the low frequency range, such as thermospheric drag and solar radiation pressure, which can easily be done by applying a high-pass filter, disturbing signals from onboard instruments such as thruster firing events or heater switch events need to be removed from the previously filtered data. Afterwards the spikes which are induced by the torquers can be very well observed. Spikes vary in amplitude with respect to an increasing or decreasing current used for magnetic torquers, and can be as large as 20 nm/s 2 . Furthermore, we were able to set up a model for the spikes of each scenario with which we were able to compute model spike time series. With these time series the spikes can successfully be removed from the 10 Hz raw accelerometer data. Spectral analysis of the time series reveal that an influence onto gravity field determination due to these effects is very unlikely, but can theoretically not be excluded.",
keywords = "Accelerometer, GRACE, Magnetic Torquers",
author = "Nadja Peterseim and Jakob Flury and Anja Schlicht",
note = "Funding Information: First of all we would like to thank the Center for Space Research (CSR) of the University of Texas at Austin for supplying us with the 10 Hz accelerometer data this work is basically based upon. Additionaly, the work of Gerhard Kruizinga for his program for correction of the time-tags of the accelerometer data is greatly acknowledged. Also, we would like to thank Helmholtz–Zentrum Potsdam, Deutsches GeoForschungsZentrum (GFZ) and the Jet Propulsion Laboratory (JPL) for supplying us with Level 1b data via their data centers ISDC and PO.DAAC. Furthermore, we would like to thank Daniel Bindel from ZARM Bremen for providing technical information on the magnetic torquers. The Bundesministerium f{\"u}r Bildung und Forschung (BMBF, German Federal Ministry of Education and Research) is acknowledged for financial support of this study within the Lotse-CHAMP/GRACE project (03G0728C) of the GEOTECHNOLOGIEN Programme.",
year = "2012",
month = may,
day = "1",
doi = "10.1016/j.asr.2012.02.013",
language = "English",
volume = "49",
pages = "1388--1394",
journal = "Advances in space research",
issn = "0273-1177",
publisher = "Elsevier Ltd.",
number = "9",
}