Cryogenic Magnetic Gradiometers for Space Applications

This article proposes the use of superconducting magneticgradiometer, magnetometer sensors based on SQUID technology as sensorsfor space-borne magnetic investigations. The existing state of theart of such sensors is described. Estimates of their performance as spacesensors is made; in particular, it is shown that they will provide magneticdata of improved sensitivity and accuracy over conventional magneticsensors. It is also found that gradiometers of the sensitivity proposedhere will aid in the analytic continuation of field data, will allowseparation of magnetic field temporal variations from field changes dueto flight past fixed magnetic sources, will provide the ability to makemeaningful measurements of fixed anomalies on magnetosphericallyactive days, and will allow increased spatial resolution of magneticsources. The requirements for a high-performance space gradiometersensor are described as well as current progress aimed at achievingsuch a sensor. Satellite system requirements are also addressed. Particularattention is given to magnetic noise sources in the sensor environmentand to the problems associated with reducing this noise to thedesired sensor noise levels.