MAG Engineering Technical Write-up
PI: Dr. David J. Southwood
MAG General Description:
The primary objective of the Dual Technique Magnetometer (MAG) is
to determine the planetary magnetic fields and the dynamic
interactions in the planetary environment.
MAG Scientific Objectives:
- To determine the internal magnetic field of Saturn.
- To develope a three-dimensional model of Saturn's
magnetosphere.
- To determine the magnetic state of Titan and its
atmosphere.
- To derive an empirical model of
the Titan electromagnetic environment.
- To investigate the interactions of Titan with the
magnetosphere, magnetosheath, and solar wind.
- To survey the ring and dust interactions with the
electromagnetic environment.
- To study the interactions of the icy satellites with
the magnetosphere of Saturn.
- To investigate the structure of the magnetotail
and the dynamic processes therein.
MAG Sensing Instruments:
- Vector/Scalar Helium Magnetometer
- Fluxgate Magnetometer
MAG Instrument Characteristics:
- Mass (current best estimate) = 3.00 kg
- Average Operating Power (current best estimate) = 3.10 W
- Average Data Rate (current best estimate) = 3.60 kilobits/s
Magnetometers are direct-sensing instruments that detect and measure the
strength of magnetic fields in the vicinity of the spacecraft. The
Cassini Dual-Technique Magnetometer (MAG) measures magnetic fields
during the Titan and Saturn encounters. The MAG consists of a vector/scalar
helium magnetometer sensor, a fluxgate magnetometer sensor, a data
processing unit, three power supplies, plus operating software and
electronics associated with the sensors.
The vector/scalar helium magnetometer (V/SHM) sensor is used to make
both vector (magnitude and direction) and scalar (magnitude only)
measurements of magnetic fields. The V/SHM and its electronics are
being supplied by JPL. The fluxgate magnetometer (FGM) sensor is used
to make vector field measurements. This sensor and its electronics are
being provided by the Imperial College of London.
The instrument data processing unit (DPU) is the responsibility of the
Technical University of Braunschweig. The DPU interfaces with the
spacecraft Command and Data Subsystem through the JPL-designed bus
interface unit (BIU). All commands, data, and processor program
changes are received or transmitted through the BIU. The MAG
components are powered by three power supplies plus the 30-volt
spacecraft bus. Power supply 0 powers the BIU and the DPU. Power
supplies 1 and 2 are redundant and power the V/SHM electronics. The
FGM electronics are powered by the spacecraft bus.
Since magnetometers are sensitive to electric currents and ferrous
components on the spacecraft, they are generally
placed on an extended boom, as far from the spacecraft as possible. In
this case, the FGM sensor is located midway out on the Cassini
magnetometer boom, and the V/SHM sensor is located at the end of
the boom. The boom itself, composed of thin, nonmetallic rods, will
be collapsed very compactly during launch and deployed only after the
spacecraft has separated from the launch vehicle.
