The GOES-16 Spacecraft Science Magnetometer

Since their inception in the 1970s, the NOAA Geostationary Operational Environmental Satellite (GOES) system has monitored the sources of space weather on the sun and the effects of space weather at Earth. These observations are important for providing forecasts, warnings and alerts to many customers, including satellite operators, the power utilities, and NASA’s human activities in space. The GOES magnetometer provides observations of the geomagnetic field, which can be the first indication that significant space weather has reached Earth. In addition, the magnetic field observations are used to identify and forecast the severity of the space weather activity. This paper reviews the capabilities of the GOES-16 magnetometer (MAG) and presents initial post-launch calibration/validation results including issues found in the data. The GOES-16 MAG requirements and capabilities are similar to those for previously flown instruments, measuring three components of the geomagnetic field but with an improved sampling rate of 10 samples/second. The MAG data are low-pass filtered with a 2.5 Hz cutoff compared to the 0.5 Hz cutoff of previous GOES magnetometers. The MAG is composed of two magnetometers, an inboard (closer to spacecraft bus) and outboard (on tip of boom) magnetometer. Presented are the science and instrument requirements, ground and initial on-orbit instrument calibration and data validation. The on-orbit analysis found magnetic contamination along with temperature dependency effects that resulted in unexpected instrument noise and decreased accuracy, with the issues generally more significant on the inboard magnetometer. The outboard sensor was used for initial analysis of MAG performance. Preliminary comparison, excluding arcjet firing periods, between the outboard magnetometer and the GOES-14 magnetometer found a statistical difference of 5 nT at 3σ for the total field. This comparison does not consider inaccuracies in the GOES-14 magnetometer. Future studies will focus on optimizing the outboard sensor performance.