Calibration and Validation of the TEMPEST-D Radiometer

The TEMPEST-D satellite is a 6U CubeSat technology demonstration mission with a five-frequency cross-track scanning millimeter-wave radiometer as its payload. It was launched on board the Orbital ATK (OA-9) commercial resupply mission for the International Space Station on May 21, 2018 and successfully deployed from the station on July 13. One of the primary goals of the TEMPEST-D mission is to demonstrate that the calibration of the millimeter-wave radiometer is sufficient for Earth science applications, specifically to meet the science requirements for constellation of five or more identical satellites/radiometers flying in formation at three- to five-minute intervals to observe the onset and evolution of convective storm systems. Validation of the TEMPEST-D calibration is performed using coincident overpasses with GPM GMI, as well as MHS on board the operational NOAA and MetOp polar orbiting satellites. The TEMPEST-D channels are very similar to those of the MHS instrument, which is very well calibrated and consistent among the four currently operating sensors. After deployment of the TEMPEST-D satellite, a series of on-orbit maneuvers will be performed, including pitching the spacecraft to view deep space over the Earth view portion of the scan and rolling the spacecraft to scan across the transition from Earth to space. Data from these maneuvers will be used to characterize the instrument antenna pattern, including spillover effects as a function of scan position. Results on the consistency of the radiometer calibration across the scan and over time will be discussed, along with comparisons with the GMI and MHS instruments, focusing on the capabilities and limitations of the TEMPEST-D millimeter-wave radiometer relative to the much larger operational instruments for Earth science applications.