The STP-H8 COWVR and TEMPEST-H8 Sensors: Two Years of On-orbit Operations

On December 21, 2021, SpaceX CRS-24 launched the DoD Space Test Program – Houston 8 (STP-H8) sensor pallet to the International Space Station (ISS) hosting two microwave radiometers: the Compact Ocean Wind Vector Radiometer (COWVR) and the Temporal Experiment for Storms and Tropical Systems – H8 (TEMPEST-H8). Sponsored by Space Systems Command (SSC), these sensors are to augment DoD remote sensing capabilities in ocean surface wind vector (OSVW) and atmospheric retrievals, at a fraction of the cost of heritage sensors. The primary mission objective is to characterize and demonstrate the end-to-end COWVR performance relative to WindSat on-orbit performance and mission requirements. A successful COWVR mission will demonstrate a lower-cost sensor architecture for providing imaging passive microwave data, including OSVW products for the DoD.

The COWVR technology demonstration is a fully polarimetric, conically-scanning imaging microwave radiometer for measuring the OSVW. The novel COWVR design features include 1) the use of a single multi-frequency feed horn enabling a simple antenna rotating about the feed axis design (as opposed to spinning the entire radiometer system); 2) internal calibration sources which eliminate the need for an external warm load and cold sky reflector simplifying the mechanical design and enabling fully-polarimetric calibration; and 3) a compact MMIC receiver implementation, lowering the system mass and power making the system well suited as a payload on smaller satellites. COWVR operates at 18.7 GHz, 23.8 GHz, and 33.9 GHz using a single stationary multi-frequency feed horn that illuminates the rotating reflector generating a 360-degree un-blocked conical scan at a spatial resolution <30km and a swath width of ~890km from the mission orbit altitude of 400km.

The COWVR is to be utilized by US Navy Fleet Numerical and Meteorology and Oceanography Center (FNMOC) which converts raw instrument data to OSVW data and other legacy microwave imager data products. Once the novel sensor concept is demonstrated with complete calibration/validation, COWVR data will be processed operationally at FNMOC using the JPL provided sensor Ground Data Processing Software (GDPS) and disseminated to end users in the form of Raw Data Records (RDRs), Temperature/Sensor Data Records (TSDRs), and Environmental Data Records (EDRs) (collectively, referred to xDRs).

This presentation will describe the mission’s sensors radiometric and geophysical retrieval performances, and impact to space-based environmental monitoring derived from 2 years of on-orbit observations.