Tropospheric water and cloud ICE (TWICE) millimeter and submillimeter-wave radiometer instrument for 6U-Class nanosatellites

Global measurements of cloud ice particle size, total ice water content and water vapor content in the upper troposphere are critically needed to improve knowledge of the role of ice clouds in Earth's climate, precipitation and cloud processes. Such observations will enable improvement in cloud and moisture simulations in global climate models as well as precipitation forecasts on a global basis. Measurements at a range of frequencies in the millimeter- and submillimeter-wave frequency range provide sensitivity to ice particle size distribution in the range of tens to hundreds of micrometers. To perform this measurement on a global basis, a new millimeter- and submillimeter-wave instrument is currently under development with suitable mass, power and volume to be deployed on 6U-Class nanosatellites. To achieve miniaturized receivers in this frequency range, InP MMIC technology has been scaled to 25-nm gate length transistors, enabling demonstration of low-noise amplifiers with sufficient gain at frequencies up to 1 THz. This technology is being applied to develop direct-detection submillimeter-wave receivers at 240 GHz, 310 GHz and 670 GHz. InP MMIC technology has also enabled multipliers for local oscillators and subharmonic mixers for temperature and humidity sounding channels near atmospheric absorption lines at 118.75, 183.31 and 380.20 GHz.