This paper describes a measurement method for characterizing the reflectivity of blackbodies used as calibration devices in spaceborne instruments. The fundamental measurement principle is based on the scattering matrix theory. A monostatic apparatus has been developed to implement the reflectivity measurements up to 220 GHz. A few blackbody emitters made of metamaterials were measured at a number of radiometric frequencies. The results demonstrated the feasibility of using metamaterial blackbodies on miniaturized satellite platforms.

The Smart Ice Cloud Sensing (SMICES) is an active/passive sensor. SMICES is sponsored by NASA Earth Science Technology Office (ESTO) under Instrument Incubator Program 19 (IIP-19) awarded to Northrop Grumman Corporation (NGC) and Jet Propulsion Laboratory (JPL). The instrument is designed to measure upper tropospheric and lower stratospheric cloud ice and water vapor. SMICES uses a suite of passive radiometers that are constantly conically scanning to locate ice clouds. The ice clouds are located using an artificial intelligence controller that identifies key labels related to the ice cloud. Once an ice cloud is identified, the artificial intelligence controller activates and targets the on-board radar. While the SMICES instrument is currently being developed for an airborne demonstration, the final goal is to deploy it as a small satellite (SmallSat) instrument in low-Earth orbit (LEO). The onboard AI controller will significantly reduce DC power consumption of the satellite mission. This will enable the SMICES system to be hosted on a smaller platform with fewer solar cells and significantly drive down mission costs while maintaining the quality of scientific data. This work presents the latest development on the SMICES microwave radiometer.

In this work, we present metamaterial-based microwave absorbers fabricated on organic-based printed circuit boards as promising alternatives to traditional, bulky microwave absorbers for the calibration of microwave radiometers for atmospheric remote sensing. Their use is particularly attractive for onboard calibration of sensors on CubeSats and other small satellites. Planar metamaterials can be fabricated with near-unity absorption over a very broad frequency range, and are scalable by tuning the unit cell geometry. Specifically, we describe an approach and initial measurements toward designing a broadband metamaterial emitter operating at millimeter wave sounding channels from 50 GHz 230 GHz, enabling a thin, cost-effective calibration target for millimeterwave atmospheric remote sensing.

The Smart Ice Cloud Sensing (SMICES) instrument aims at providing onboard smart autonomous observation of upper tropospheric water vapor and ice particle size distribution in clouds at various local times. SMICES is an active/passive combined sensor with sounding channels at 380 GHz, radiometric channels at 250, 310 and 670 GHz, and a radar instrument operating at 239 GHz. A low-noise, low-power radiometer command and data handling (C&DH) subsystem has been designed to acquire the 24 analog radiometer channels and 8 analog thermistor data. A radiometric power regulation system provides the required power supplies for the other radiometric subsystems of the SMICES instrument. An on-board FPGA provides command and control of other instrument subsystems, performs synchronous data acquisition. The radiometer electronics are designed to fit into less than 2U horizontal dimensions of a CubeSat instrument. An AI controller unit directly interfacing with radar and radiometer C&DH subsystems performs on-board artificial intelligence operations for full system autonomy. The AI unit will control the radar instrument depending on the system health conditions, including the battery level, and based on the observed scene through the radiometer instrument.

Global observations with information content on water vapor content, ice water content and ice particle size distribution are needed to enhance knowledge of the impact of ice clouds on Earth's weather and climate. These observations may also help to reduce the uncertainty of global climate models. The Tropospheric Water and Cloud Ice (TWICE) microwave radiometer instrument has been designed to perform temperature and humidity sounding of the atmosphere near the 118.75, 183.31 and 380.20 GHz atmospheric absorption lines, as well as to retrieve ice cloud particle size information from radiometric measurements at 240, 310, 670 and 850 GHz. To acquire high-quality data, the TWICE instrument performs end-to-end, on-orbit calibration of all radiometer channels during each scan. The TWICE instrument is designed to fit within the mass, volume and power constraints of the 6U CubeSat platform.

The Tropospheric Water and Cloud ICE (TWICE) millimeter and sub-millimeter radiometer instrument is being developed to enable global observations of upper tropospheric/lower-stratospheric water vapor and ice particle size distribution in clouds. Global observations using the TWICE instrument are critically needed to reduce uncertainties in weather and climate models. A low-noise, power-efficient command and data handling (C&DH) subsystem has been designed and tested to control TWICE data acquisition and other subsystems. Considering the limited power resources available on such platforms, a highly-efficient power regulation board has been designed to minimize power losses and reduce system noise. Furthermore, heavy-ion radiation testing has been performed for some critical commercial-off-the-shelf components to analyze radiation tolerance in low-Earth orbit. The C&DH prototype board meets the functional, noise and size, weight and power (SWaP) requirements for deployment on a 6U -Class satellite.

Global measurements of upper tropospheric/lower-stratospheric water vapor and ice particle size distribution in clouds are critically needed to reduce uncertainties in global weather and climate models. To address this need, the conically scanning Tropospheric Water and Cloud ICE (TWICE) millimeter and submillimeter radiometer instrument is being developed. A low-noise, power-efficient command and data handling (C&DH) subsystem has been designed to control TWICE data acquisition and other subsystems. The C&DH prototype board meets functional, noise and size, weight and power (SWaP) requirements for deployment in a 6U-class satellite. Considering the limited power resources available on such platforms, a highly-efficient power regulation board has been designed to minimize power losses and reduce system noise. Furthermore, all of the components have been tested for radiation tolerance in low-Earth orbit.

With the advent and fast-paced development of ultrahighspeed digital interconnects for next-generation computing systems, low-latency broadband wireless communications for fifth generation and beyond, high-resolution imaging techniques and emerging parametric sensing systems for medical/biomedical and security applications, material and structure analyses and evaluations, and deep-space radio astrophysics, and so on, the search for system solutions with larger bandwidth has sparked a growing research in expanding the electromagnetic spectrum into the terahertz (THz) regime. Generally, the THz frequency covers 300 GHz through 10 THz, which presents the most fundamental spect rum gap between elect ronics and photonics.