SCIENCE CALIBRATION AND ALIGNMENT SUBSYSTEM (SCAS)

The Science Calibration And Alignment Subsystem (SCAS) provides quantified alignment standards for the Magnetometer (MAG) Subsystem throughout the mission. These standards permit verification of MAG instrument alignment on a routine basis.

The SCAS consists of three interconnected subassemblies: the X-magnetometer alignment coil, the Y-magnetometer alignment coil, and the magnetometer alignment coil electronics. For information on these components, click on their names.

The X-magnetometer alignment coil (X-MAC) is mounted parallel to the magnetometer boom axis in the perimeter of the spacecraft electronics bus Bay 7 outboard shear plate. The coil consists of 179 turns of No. 26 AWG copper magnet wire, and when it is energized with 30-volt d.c. power it generates a magnetic field with a component parallel to the spacecraft X axis at the vector/scalar helium magnetometer location. A platinum resistance transducer is mounted in proximity to the X-MAC to measure the operating temperature of the unit.

The Y-magnetometer alignment coil (Y-MAC) is mounted parallel to the magnetometer boom axis in the perimeter of the spacecraft electronics bus Bay 4 outboard shear plate. This coil consists of 89 turns of No. 29 AWG copper magnet wire, and when it is energized with 30-volt d.c. power it generates a magnetic field with a component parallel to the spacecraft Y axis at the V/SHM location. As with the X-MAC, a platinum resistance transducer is mounted in proximity to the Y-MAC to measure the operating temperature of the unit.

The magnetometer alignment coil electronics (MAC-E) provide the circuitry to switch polarity and to power the X-MAC and Y-MAC alternately when 30-volt d.c. power from the Power and Pyrotechnic Subsystem (PPS) is applied.



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