Abstract
Abstract Ground calibration experiments of the SELENE high sensitivity fluxgate Lunar Magnetometer (LMAG) have been performed in order to determine the alignment, sensitivity, and offset of the sensors (MGF-S). It is checked out that the sensors are orthogonal to each other within 0.4 degrees, and the linearity of the ambient magnetic field and the output from the sensors are confirmed. Also, the temperature dependences of the offset and sensitivity are examined but no clear signatures of temperature dependencies can be seen. SELENE has an in-flight calibration system in order to determine the direction of the magnetometer routinely. The magnetic fields generated by the sensor alignment monitor coil (SAM-C) system are used for the in-flight calibration. The magnetic field distributions generated by SAM-C are determined and the accuracy of determination of the magnetometer position and direction is estimated. Multiple measurements will allow us to determine the direction of MGF-S with about 0.1-degree accuracy. Appropriate corrections from the results of the ground and in-flight calibrations will allow us to recover the magnetic field near the moon with accuracy about 0.1 nT.
Highlights
Observations of the lunar magnetic field have been conducted occasionally since 1969, from Apollo 12 to Lunar Prospector
We have developed a sensor alignment monitor coil system (SAM-C) employing a bi-axis coil configuration in order to generate two linearly independent magnetic field
Summary The ground calibration of SELENE magnetometer has been made by a series of experiments
Summary
Observations of the lunar magnetic field have been conducted occasionally since 1969, from Apollo 12 to Lunar Prospector. Monitoring the alignment of the MGF-S with respect to spacecraft is required to obtain a reliable magnetic field vector in the vicinity of the moon, and SELENE has an in-flight calibration system. This kind of system is necessary because the mast, on which MGF-S is installed, may be deformed more or less by thermal expansion if the satellite is in day or night side and the difference of the the relative position and angle of the magnetic sensors to the spacecraft may possibly be significant.
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