Exploring planetary magnetic environments using magnetically unclean spacecraft: a systems approach to VEX MAG data analysis

Abstract. In situ measurements of the magnetic field are vital to the study of many fundamental problems in planetary research. Therefore the magnetometer experiment is a key element of the payload of Venus Express. In addition to the interaction of the solar wind with Venus, these measurements are crucial for the study of atmospheric escape and detection of lightning. However, the methodology for the magnetic field measurements had to be different to the traditional approach, because Venus Express is not a magnetically clean spacecraft. A technique based on two-point simultaneous measurements of the magnetic field and systems identification software is used to separate the natural magnetic field from the spacecraft generated interference. In this paper an overview of the techniques developed to separate these two field types and the results achieved for 1 Hz Venus Express data are presented. Previous publications suggest that the resulting Venus Express cleaned data is of comparable quality to measurements made from onboard magnetically clean spacecraft (Zhang et al., 2008a, b; Slavin et al., 2009).

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Principal Component Gradiometer technique for removal of spacecraft-generated disturbances from magnetic field data

10.5194/gi-2020-10 ◽

2020 ◽

Cited By ~ 1

Author(s):

Ovidiu Dragoş Constantinescu ◽

Hans-Ulrich Auster ◽

Magda Delva ◽

Olaf Hillenmaier ◽

Werner Magnes ◽

...

Keyword(s):

Magnetic Field ◽

Principal Component ◽

Field Measurements ◽

Magnetic Field Data ◽

Service Oriented ◽

Sensor Configuration ◽

Time Required ◽

First Time ◽

The Magnetic Field

Abstract. In situ measurement of the magnetic field using space borne instruments requires either a magnetically clean platform and/or a very long boom for accommodating magnetometer sensors at a large distance from the spacecraft body. This significantly drives up the costs and time required to build a spacecraft. Here we present an alternative sensor configuration and an algorithm allowing for ulterior removal of the spacecraft generated disturbances from the magnetic field measurements, thus lessening the need for a magnetic cleanliness program and allowing for shorter boom length. The proposed algorithm is applied to the Service Oriented Spacecraft Magnetometer (SOSMAG) onboard the Korean geostationary satellite GeoKompsat-2A (GK2A) which uses for the first time a multi-sensor configuration for onboard data cleaning. The successful elimination of disturbances originating from several sources validates the proposed cleaning technique.

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Cleaning magnetometer data using multi sensor configuration

10.5194/egusphere-egu2020-17741 ◽

2020 ◽

Author(s):

Dragos Constantinescu ◽

Hans-Ulrich Auster ◽

Magda Delva ◽

Olaf Hillenmaier ◽

Werner Magnes ◽

...

Keyword(s):

Magnetic Field ◽

Field Measurements ◽

Sensor Arrangement ◽

Magnetometer Data ◽

Service Oriented ◽

Sensor Configuration ◽

First Time ◽

The Magnetic Field ◽

Magnetic Cleanliness

Measuring the in situ magnetic field using space borne instruments requires either a magnetically clean platform and/or a very long boom for accommodating magnetometers sensors at a large distance from the spacecraft body. This significantly drives up the costs and time for building the spacecraft. Here we present an alternative sensor configuration and an algorithm allowing for ulterior removing of the spacecraft generated disturbances from the magnetic field measurements, thus lessening the need for a magnetic cleanliness program.The Service Oriented Spacecraft Magnetometer (SOSMAG) onboard the Korean Geostationary Satellite GEO-KOMPSAT-2A (GK-2A) uses for the first time a multi-sensor configuration for onboard data cleaning. To remove the AC disturbances, a combination of the measurements from sensors placed at different positions from the disturbance sources is processed onboard. Sensor biases due to daily temperature variations are also removed using the specific SOSMAG sensor arrangement.&#160;&#160;

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Maximum-variance gradiometer technique for removal of spacecraft-generated disturbances from magnetic field data

Geoscientific Instrumentation Methods and Data Systems ◽

10.5194/gi-9-451-2020 ◽

2020 ◽

Vol 9 (2) ◽

pp. 451-469

Author(s):

Ovidiu Dragoş Constantinescu ◽

Hans-Ulrich Auster ◽

Magda Delva ◽

Olaf Hillenmaier ◽

Werner Magnes ◽

...

Keyword(s):

Magnetic Field ◽

Field Measurements ◽

Magnetic Field Data ◽

Maximum Variance ◽

Service Oriented ◽

Corrected Data ◽

Sensor Configuration ◽

Time Required ◽

The Magnetic Field

Abstract. In situ measurement of the magnetic field using spaceborne instruments requires a magnetically clean platform and/or a very long boom for accommodating magnetometer sensors at a large distance from the spacecraft body. This significantly drives up the costs and the time required to build a spacecraft. Here we present an alternative sensor configuration and a technique allowing for removal of the spacecraft-generated AC disturbances from the magnetic field measurements, thus lessening the need for a magnetic cleanliness programme and allowing for shorter boom length. The final expression of the corrected data takes the form of a linear combination of the measurements from all sensors, allowing for simple onboard software implementation. The proposed technique is applied to the Service Oriented Spacecraft Magnetometer (SOSMAG) on board the Korean geostationary satellite GeoKompsat-2A (GK2A). In contrast to other missions where multi-sensor measurements were used to clean the data on the ground, the SOSMAG instrument performs the cleaning on board and transmits the corrected data in real time, as needed by space weather applications. The successful elimination of the AC disturbances originating from several sources validates the proposed cleaning technique.

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Automatic parameterization for magnetometer zero offset determination

Geoscientific Instrumentation Methods and Data Systems ◽

10.5194/gi-1-103-2012 ◽

2012 ◽

Vol 1 (2) ◽

pp. 103-109 ◽

Cited By ~ 3

Author(s):

M. A. Pudney ◽

C. M. Carr ◽

S. J. Schwartz ◽

S. I. Howarth

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Field Measurements ◽

Slow Solar Wind ◽

Fixed Parameter ◽

Zero Offset ◽

Parameter Approach ◽

The Magnetic Field ◽

Key Parameter

Abstract. In-situ magnetic field measurements are of critical importance in understanding how the Sun creates and controls the heliosphere. To ensure the measurements are accurate, it is necessary to track the combined slowly varying spacecraft magnetic field and magnetometer zero offset – the systematic error in the sensor measurements. For a 3-axis stabilised spacecraft, in-flight correction of zero offsets primarily relies on the use of Alfvénic rotations in the magnetic field. We present a method to automatically determine a key parameter related to the ambient compressional variance of the signal (which determines the selection criteria for identifying clear Alfvénic rotations). We apply our method to different solar wind conditions, performing a statistical analysis of the data periods required to achieve a 70% chance of calculating an offset using Helios datasets. We find that 70% of 40 min data periods in regions of fast solar wind possess sufficient rotational content to calculate an offset. To achieve the same 70% calculation probability in regions of slow solar wind requires data periods of 2 h duration. We also find that 40 min data periods at perihelion compared to 1 h and 40 min data periods at aphelion are required to achieve the same 70% calculation probability. We compare our method with previous work that uses a fixed parameter approach and demonstrate an improvement in the calculation probability of up to 10% at aphelion and 5% at perihelion.

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Automatic parameterization for magnetometer zero offset determination

Geoscientific Instrumentation Methods and Data Systems Discussions ◽

10.5194/gid-2-245-2012 ◽

2012 ◽

Vol 2 (1) ◽

pp. 245-266

Author(s):

M. A. Pudney ◽

C. M. Carr ◽

S. J. Schwartz ◽

S. I. Howarth

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Field Measurements ◽

Slow Solar Wind ◽

Fixed Parameter ◽

Zero Offset ◽

Parameter Approach ◽

The Magnetic Field ◽

Key Parameter

Abstract. In-situ magnetic field measurements are of critical importance in understanding how the Sun creates and controls the heliosphere. To ensure the measurements are accurate, it is necessary to track the combined slowly-varying spacecraft magnetic field and magnetometer zero offset – the systematic error in the sensor measurements. For a 3-axis stabilised spacecraft, in-flight correction of zero offsets primarily relies on the use of Alfvénic rotations in the magnetic field. We present a method to automatically determine a key parameter related to the ambient compressional variance of the signal (which determines the selection criteria for identifying clear Alfvénic rotations). We apply our method to different solar wind conditions, performing a statistical analysis of the data periods required to achieve a 70% chance of calculating an offset using Helios datasets. We find that 70% of 40 min data periods in regions of fast solar wind possess sufficient rotational content to calculate an offset. To achieve the same 70% calculation probability in regions of slow solar wind requires data periods of 2 h duration. We also find that 40 min data periods at perihelion compared to 1 h and 40 min data periods at aphelion are required to achieve the same 70% calculation probability. We compare our method with previous work that uses a fixed parameter approach and demonstrate an improvement in the calculation probability of up to 10% at aphelion and 5% at perihelion.

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Scattering of field-aligned beam ions upstream of Earth's bow shock

Annales Geophysicae ◽

10.5194/angeo-25-785-2007 ◽

2007 ◽

Vol 25 (3) ◽

pp. 785-799 ◽

Cited By ~ 24

Author(s):

A. Kis ◽

M. Scholer ◽

B. Klecker ◽

H. Kucharek ◽

E. A. Lucek ◽

...

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Field Measurements ◽

Bow Shock ◽

Ion Distribution ◽

Parallel Side ◽

Earth’S Bow Shock ◽

High Mach ◽

The Magnetic Field

Abstract. Field-aligned beams are known to originate from the quasi-perpendicular side of the Earth's bow shock, while the diffuse ion population consists of accelerated ions at the quasi-parallel side of the bow shock. The two distinct ion populations show typical characteristics in their velocity space distributions. By using particle and magnetic field measurements from one Cluster spacecraft we present a case study when the two ion populations are observed simultaneously in the foreshock region during a high Mach number, high solar wind velocity event. We present the spatial-temporal evolution of the field-aligned beam ion distribution in front of the Earth's bow shock, focusing on the processes in the deep foreshock region, i.e. on the quasi-parallel side. Our analysis demonstrates that the scattering of field-aligned beam (FAB) ions combined with convection by the solar wind results in the presence of lower-energy, toroidal gyrating ions at positions deeper in the foreshock region which are magnetically connected to the quasi-parallel bow shock. The gyrating ions are superposed onto a higher energy diffuse ion population. It is suggested that the toroidal gyrating ion population observed deep in the foreshock region has its origins in the FAB and that its characteristics are correlated with its distance from the FAB, but is independent on distance to the bow shock along the magnetic field.

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Statistical relations between in-situ measured Bz component and thermospheric density variations

10.5194/egusphere-egu21-4773 ◽

2021 ◽

Author(s):

Sofia Kroisz ◽

Lukas Drescher ◽

Manuela Temmer ◽

Sandro Krauss ◽

Barbara Süsser-Rechberger ◽

...

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Field Measurements ◽

Satellite Orbit ◽

Solar Wind Plasma ◽

Statistical Investigation ◽

Neutral Density ◽

Special Focus ◽

Short Term

Through advanced statistical investigation and evaluation of solar wind plasma and magnetic field data, we investigate the statistical relation between the magnetic field Bz component, measured at L1, and Earth&#8217;s thermospheric neutral density. We will present preliminary results of the time series analyzes using in-situ plasma and magnetic field measurements from different spacecraft in near Earth space (e.g., ACE, Wind, DSCOVR) and relate those to derived thermospheric densities from various satellites (e.g., GRACE, CHAMP). The long and short term variations and dependencies in the solar wind data are related to variations in the neutral density of the thermosphere and geomagnetic indices. Special focus is put on the specific signatures that stem from coronal mass ejections and stream or corotating interaction regions.&#160; The results are used to develop a novel short-term forecasting model called SODA (Satellite Orbit DecAy). This is a joint study between TU Graz and University of Graz funded by the FFG Austria (project &#8220;SWEETS&#8221;).

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Transport of energetic particles from reconnecting current sheets in flaring corona to the heliosphere

10.5194/egusphere-egu21-15163 ◽

2021 ◽

Author(s):

Philippa Browning ◽

Mykola Gordovskyy ◽

Satashi Inoue ◽

Eduard Kontar ◽

Kanya Kusano ◽

...

Keyword(s):

Magnetic Field ◽

Energetic Particles ◽

Transport Processes ◽

Data Driven ◽

Current Sheets ◽

Electrons And Ions ◽

Data Driven Approach ◽

Particle Simulations ◽

The Magnetic Field

In this study, we inverstigate the acceleration of electrons and ions at current sheets in the flaring solar corona, and their transport into the heliosphere. We consider both generic solar flare models and specific flaring events with a data-driven approach. The aim is to answer two questions: (a) what fraction of particles accelerated in different flares can escape into the heliosphere?; and (b) what are the characteristics of the particle populations propagating towards the chromosphere and into the heliosphere?We use a combination of data-driven 3D magnetohydrodynamics simulations with drift-kinetic particle simulations to model the evolution of the magnetic field and both thermal and non-thermal plasma and to forward-model observable characteristics. Particles are accelerated in current sheets associated with flaring reconnection. When applied to a specific flare, the model successfully predicts observed features such as the location and relative intensity of hard X-ray sources and helioseismic source locations. This confirms the viability of the approach.Using these MHD-particle models, we will show how the magnetic field evolution and particle transport processes affect the characteristics of both energetic electrons and ions in the the inner corona and the heliosphere. The implications for interpretation of in situ measurements of energetic particles by Solar Orbiter and Parker Solar Probe will be discussed.&#160;&#160;

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Attitude Estimation of Underwater Vehicles Using Field Measurements and Bias Compensation

Sensors ◽

10.3390/s19020330 ◽

2019 ◽

Vol 19 (2) ◽

pp. 330 ◽

Cited By ~ 2

Author(s):

Nak Ko ◽

Seokki Jeong ◽

Suk-seung Hwang ◽

Jae-Young Pyun

Keyword(s):

Magnetic Field ◽

Field Measurement ◽

Field Measurements ◽

Underwater Vehicle ◽

Field Vector ◽

Attitude Estimation ◽

Magnetic Field Measurement ◽

Euler Angles ◽

Measured Field ◽

The Magnetic Field

This paper proposes a method of estimating the attitude of an underwater vehicle. The proposed method uses two field measurements, namely, a gravitational field and a magnetic field represented in terms of vectors in three-dimensional space. In many existing methods that convert the measured field vectors into Euler angles, the yaw accuracy is affected by the uncertainty of the gravitational measurement and by the uncertainty of the magnetic field measurement. Additionally, previous methods have used the magnetic field measurement under the assumption that the magnetic field has only a horizontal component. The proposed method utilizes all field measurement components as they are, without converting them into Euler angles. The bias in the measured magnetic field vector is estimated and compensated to take full advantage of all measured field vector components. Because the proposed method deals with the measured field independently, uncertainties in the measured vectors affect the attitude estimation separately without adding up. The proposed method was tested by conducting navigation experiments with an unmanned underwater vehicle inside test tanks. The results were compared with those obtained by other methods, wherein the Euler angles converted from the measured field vectors were used as measurements.

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Magnetospheric Processes Possibly Related to the Origin of Cosmic Rays

Symposium - International Astronomical Union ◽

10.1017/s0074180900074921 ◽

1981 ◽

Vol 94 ◽

pp. 373-391

Author(s):

Gerhard Haerendel

Keyword(s):

Magnetic Field ◽

Large Scale ◽

Small Scale ◽

Shear Stresses ◽

Acceleration Process ◽

Dayside Magnetopause ◽

Field Lines ◽

The Magnetic Field ◽

Auroral Particles

Two processes are discussed which violate the frozen-in condition in a highly conducting plasma, reconnection and the auroral acceleration process. The first applies to situations in which . It plays an important role in the interaction of the solar wind with the Earth's magnetic field and controls energy input into as well as energetic particle release from the magnetosphere. Detailed in situ studies of the process on the dayside magnetopause reveal its transient and small-scale nature. The auroral acceleration process occurs in the low magnetosphere (β « 1) and accompanies sudden releases of magnetic shear stresses which exist in large-scale magnetospheric-ionospheric current circuits. The process is interpreted as a kind of breaking. The movements of the magnetospheric plasma which lead to a relief of the magnetic tensions occur in thin sheets and are decoupled along the magnetic field lines by parallel electric potential drops. It is this voltage that accelerates the primary auroral particles. The visible arcs are then traces of the magnetic breaking process at several 1000 km altitude.

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