Spacecraft Magnetometer - Configurations of Magnetometers - Dual Technique

Dual Technique

Each type of magnetometer has its own built in 'weakness'. This can result from the design of the magnetometer to the way the magnetometer interacts with the spacecraft, radiation from the sun, resonances, etc. Using completely different design is a way to measure which readings are the result of natural magnetic fields and the sum of magnetic fields altered by spacecraft systems. In addition each type has its strengths. The fluxgate type is relatively good at providing data that finds magnetic sources. One of the first Dual technique systems was the abbreviated Explorer 10 mission which used a rubidium vapor and biaxial fluxgate magnetometers. Vector helium is better at tracking magnetic field lines and as a scalar magnetometer. Cassini spacecraft used a Dual Technique Magnetometer. One of these devices is the ring-coil vector fluxgate magnetometer (RCFGM). The other device is a vector/scalar helium magnetometer. The RCFGM is mounted 5.5 m out on an 11 m boom with the helium device at the end.

Explorer 6 (1959) used a search coil magnetometer to measure the gross magnetic field of the Earth and vector fluxgate., however because of induced magnetism is the space craft the fluxgate sensor became saturated and did not send data. Future missions would attempt to place magnetometers further away from the space craft.

Magsat Earth geological satellite was also Dual Technique. This satellite and Grm-A1 carried a scalar cesium vapor magnetometer and vector fluxgate magnetometers. The Grm-A1 satellite carrier the magnetometer on 4 meter boom. This particular spacecraft was designed to hold in a precised equi-gravitational orbit, while taking measurements. For purposes similar to Magsat, the Ørsted satellite, also used a dual technique system. The Overhauser magnetometer is situated at the end of an 8 meter long boom, in order to minimize disturbances from the satellite's electrical systems. The CSC fluxgate magnetometer is located inside the body and associated with a star tracking device. One of the greater accomplishments of the two missions, the Magsat and Orsted missions happen to capture a period of great magnetic field change, with the potential of a loss of dipole, or pole reversal.