Improved GOES-17 Magnetometer Zero Offset Electronics Unit Thermal Calibration

The Geostationary Operational Environmental Satellite-R (GOES-R) is a series of four NOAA weather satellites. Each spacecraft flies a Magnetometer instrument which includes two boom mounted fluxgate sensors housed in Sensor Units (SUs) located 6.3 and 8.5 meters from the spacecraft. Each SU is connected to an Electronics Unit (EU) in the body of the spacecraft. The GOES-R Magnetometers provide critical magnetospheric data for space weather applications.

The GOES-17 observatory, which is part of the NOAA GOES-R Series constellation of weather satellites, was launched on 1 March 2018. Comparisons of the calibrated data from the two GOES-17 Magnetometers shows a bias error correlated to events where the EUs are subjected to a highly dynamic thermal environment. To characterize the error, spacecraft heaters were used to quickly elevate the EU temperatures at the same time GOES-17 was co-located with GOES-15 during a drift maneuver. This allowed the GOES-15 Magnetometer data to be used as a baseline. The test indicated that the GOES-17 bias error is largely due to a significant delay between when the temperature is measured and when the bias is affected. This time delay in the response was characterized using time periods immediately following North-South maneuvers during which the EUs rapidly cool. As a result a mitigation method for the bias error was developed.