Mission Status and Calibration/Validation Updates for the Tomorrow.io Pathfinder Radar Satellites

Tomorrow.io is the first commercial entity to successfully launch radar satellites capable of precipitation profiling. The two identical Pathfinder Ka-band precipitation radar satellites, Tomorrow-R1 and Tomorrow-R2 (TR1/2), are the first phase in the deployment of an operational precipitation mapping constellation of Ka-band precipitation radars and millimeter-wave sounders. The Pathfinders are non-scanning, pencil-beam radar systems based on a 1.2 m solid Cassegrain antenna and serve as an engineering and science testbed building towards a second-generation, precipitation-mapping radar system that will constitute one-third of the approximately 30-satellite radar-radiometer constellation and provide high-revisit-rate, global weather radar observations. In anticipation of the first scanning radar deployment in the second half of 2024, the Pathfinder radar mission goals are to demonstrate critical aspects of the radar electronics, waveform sampling techniques, instrument calibration, and precipitation retrieval methods. Utilizing a state-of-the-art solid-state radar front-end and highly-reconfigurable software-defined radar digital IF transceiver, TR1/2 are the most sensitive Ka-band precipitation radars ever deployed in space with a sensitivity below 8 dBZ. Furthermore, they feature unprecedented sampling capabilities including very high duty cycle pulse compression (30%), frequency-diverse waveform sampling, a high-precision (<1 K NEdT) Ka-band radiometric mode of operation, and wideband (>400 MHz) ocean altimetry capabilities.

Here we present results from the first half-year of operations, including critical assessment of the system measurement sensitivity, precipitation rate profile retrieval development, and near-surface precipitation detection capabilities. We highlight the performance of the transceiver electronics to ensure a range-sidelobe-limited surface clutter detection floor, and discuss early validation of the calibrated reflectivity and precipitation products. Finally, we outline the capabilities of the second-generation Tomorrow.io radar system slated for initial launch in late 2024, which utilizes an electronic cross-track scan to access a 400 km ground swath with 5 km horizontal resolution, 250 m range resolution, and 12 dBZ sensitivity.