TY - JOUR

T1 - The spinning Astrid-2 satellite used for modeling the Earth's main magnetic field

A1 - Merayo,José M.G.

A1 - Jørgensen,P.S.

A1 - Risbo,T.

A1 - Brauer,Peter

A1 - Primdahl,Fritz

A1 - Cain,J.

AU - Merayo,José M.G.

AU - Jørgensen,P.S.

AU - Risbo,T.

AU - Brauer,Peter

AU - Primdahl,Fritz

AU - Cain,J.

PB - I E E E

PY - 2002

Y1 - 2002

N2 - The Swedish micro-satellite Astrid-2 was successfully launched into a near polar orbit in December 1998. Despite the fact that the primary science mission was auroral research, the magnetic instrument was designed to accomplish high-resolution and high-precision vector field magnetic measurements, and therefore mapping of the Earth's magnetic field was possible. The spacecraft spins about a highly stable axis in space. This fact and the globally distributed data make the magnetic measurements well suited for the estimate of a magnetic field model at the spacecraft altitude (about 1000 km). This paper describes the initial analysis of the Astrid-2 magnetic data. As a result of the study of a single day (February 7, 1999), magnetically fairly quiet, it was possible to in-flight adjust the calibration of the magnetometer and find a magnetic field model fitting the scalar component of the measurements to better than 5 nT(rms) for latitudes Equatorward of 50degrees. Several methods for field modeling are discussed in this paper under the assumption that the direction of the spin axis in inertial space is nearly constant, and this assumption is corroborated by the observations. The approximate inertial orientation of the magnetometer could then be determined simultaneously with the instrument intrinsic calibration and the estimate of main field model coefficients. Hence, apart from the scientific use of the magnetic data, the attitude of the spacecraft may be estimated with high precision.

AB - The Swedish micro-satellite Astrid-2 was successfully launched into a near polar orbit in December 1998. Despite the fact that the primary science mission was auroral research, the magnetic instrument was designed to accomplish high-resolution and high-precision vector field magnetic measurements, and therefore mapping of the Earth's magnetic field was possible. The spacecraft spins about a highly stable axis in space. This fact and the globally distributed data make the magnetic measurements well suited for the estimate of a magnetic field model at the spacecraft altitude (about 1000 km). This paper describes the initial analysis of the Astrid-2 magnetic data. As a result of the study of a single day (February 7, 1999), magnetically fairly quiet, it was possible to in-flight adjust the calibration of the magnetometer and find a magnetic field model fitting the scalar component of the measurements to better than 5 nT(rms) for latitudes Equatorward of 50degrees. Several methods for field modeling are discussed in this paper under the assumption that the direction of the spin axis in inertial space is nearly constant, and this assumption is corroborated by the observations. The approximate inertial orientation of the magnetometer could then be determined simultaneously with the instrument intrinsic calibration and the estimate of main field model coefficients. Hence, apart from the scientific use of the magnetic data, the attitude of the spacecraft may be estimated with high precision.

KW - modeling

KW - geophysical inverse problems

KW - data models

KW - magnetic field measurement

KW - data processing

KW - Amorphous magnetic materials

KW - geomagnetism

KW - magnetic fields

KW - calibration

KW - satellites

KW - magnetometers

KW - measurement

U2 - 10.1109/TGRS.2002.1006371

DO - 10.1109/TGRS.2002.1006371

JO - I E E E Transactions on Geoscience and Remote Sensing

JF - I E E E Transactions on Geoscience and Remote Sensing

SN - 0196-2892

IS - 4

VL - 40

SP - 898

EP - 909

ER -