The Cassini Magnetic Field Investigation

Abstract

Abstract. The dual technique magnetometer system onboard the Cassini orbiter is described. This instrument consists of vector helium and fluxgate magnetometers with the capability to operate the helium device in a scalar mode. This special mode is used near the planet in order to determine with very high accuracy the interior field of the planet. The orbital mission will lead to a detailed understanding of the Saturn/Titan system including measurements of the planetary magnetosphere, and the interactions of Saturn with the solar wind, of Titan with its environments, and of the icy satellites within the magnetosphere.

Investigation of the force balance in the Titan ionosphere: Cassini T5 flyby model/data comparisons

“…Below 1000 km altitude, the contribution of the heavier ion species that are not detected by the INMS to the total density is significant Crary et al, 2009). The MAG instrument is capable of determining the absolute magnitude of the field to an accuracy of 1 nT (Dougherty et al, 2004). RPWS and MAG data are available during the entire closest approach (CA) while INMS data are available for only the outbound leg.…”

“…In this paper, we used measurements obtained by Cassini during T5 of ion and neutral densities from INMS (Waite et al, 2004;Cravens et al, 2006Cravens et al, , 2008Magee et al, 2009;Cui et al, 2009), electron temperature and density from RPWS (Wahlund et al, 2005;Agren et al, 2007) and vector magnetic field from MAG (Dougherty et al, 2004). The INMS total ion density measurements agree well with the RPWS electron density measurements between $1000 and 1500 km altitude, where the RPWS density errors are in $10% and the INMS calibration is accurate to 20% for M/ Z < 50 daltons and 50% at M/Z of 50 daltons or higher (Agren et al, 2007;Cravens et al, 2006).…”

“…In this study, we attempt to understand Titan interaction and ionosphere in more detail by analyzing the simulation results from a single-fluid multi-species 3D MHD model run for T5 conditions, and comparing the model predictions to the Cassini Ion Neutral Mass Spectrometer (INMS) (Waite et al, 2004), Radio and Plasma Wave Science -Langmuir probe (RPWS/LP) (Gurnett et al, 2004) and magnetometer (MAG) (Dougherty et al, 2004) observations. Our approach in this study differs from previous model-measurement comparisons for Titan in that we provide an in-depth analysis of the results at low altitudes in the ionosphere rather than making global scale comparisons.…”

Planetary Magnetic Field Measurements: Missions and Instrumentation

“…It also considered the higher order, axial quadrupole and octupole terms and examined the sensitivity of these higher order terms, and in particular any non-axisymmetric terms and found that the flyby data were not sufficient to constrain them uniquely. As in all cases, orbiter spacecraft are, in principle required for a comprehensive determination of planetary magnetic fields; the arrival of the Cassini orbiter around Saturn on 1 July 2004 (Dougherty et al 2005) was the start of a new phase in the exploration of the magnetic fields and the environment of Saturn. The still-unresolved question of Saturn's The kronocentric radial distance is colour coded on the tracks and covers the range up to 6R S .…”

Calibration techniques for magnetometers implementing on-board de-spinning algorithms

“…The calibration matrix and offset vector are typically computed on a daily basis and, in the case of a spinning spacecraft such as Cluster, are related in a complex but deterministic way to the power levels of individual field component at spin and twice-spin harmonics (Kepko et al, 1996). In fact, without a secondary absolute B-field reference available on-board such as a scalar magnetometer (Dougherty et al, 2004) a complete solution to the calibration problem is extremely difficult. Nevertheless, through careful extrapolation of calibration parameters determined on ground as well as applying some statistical techniques in-flight (e.g.…”