Maintaining gradiometer accuracy on-orbit

This paper discusses the utility of slew manoeuvres and multiple magnetometers for reducing three types of magnetometer measurement error, i.e. biases, spacecraft fields and misalignments. Observability is discussed to establish what quantities can be solved for and when. Covariance estimates are then used to predict solution accuracy, and geostationary satellite data are used to corroborate the predictions. With slews and two magnetometers, it should be possible to keep ambient field errors under a few nanoteslas even on high geomagnetic activity days.