Project Selections for ACT-20

12 Projects Awarded Under the Advanced Component Technology Program

12/16/2020 – NASA’s Science Mission Directorate, NASA Headquarters, Washington, DC, has selected proposals for the Advanced Component Technology Program (ACT-20), a technology development program managed by the Earth Science Technology Office (ESTO). With the selection of 12 new projects, ESTO is demonstrating new ways to develop the next generation of highly innovative technologies for Earth science remote sensing by forging new partnerships between industry, academia, other government agencies, and NASA Centers. This ACT-20 solicitation called for disruptive technology, which involves higher risk but also has the potential for greater impact.

While the ACT-20 solicitation did not specifically request software development, proposers were asked to show, where appropriate, how innovations in artificial intelligence, machine learning, onboard processing, etc. can augment the proposed instrument architecture and/or could be used in the initial stages of the proposed component or subsystem design. Two of the projects selected exemplify the link between hardware and software design for innovative solutions. Dr. Ben Yoo (University of California, Davis) will partner with Lockheed Martin, University of Virginia, and University of Texas to introduce compression techniques on waferscale imagers to achieve high resolution hyperspectral imaging to measure carbon dioxide, methane, and solar induced fluorescence. Mr. Jim Yamaguchi (Irvine Sensors Corporation) will partner with Northrop Grumman and NASA JPL to produce Stacked Miniaturized and Radiation Tolerant Intelligent Electronics (SMARTIE). The proposed technology could bring computation in space to near the level currently achieved on the ground and is essential for future space instruments where adaptive smart sensing capabilities and onboard processing of data are required.

The ACT program is also looking for the next generation of disruptive technologies for detection of cloud and precipitation processes. Dr. Lute Maleki (OEwaves Inc.) will partner with NASA GSFC and University of California, Davis to produce a radar on a chip by using microwave photonic integrated circuits to push state-of-the-art technology and reduce the size, weight, and power requirements for future generations of multi-frequency radars and wideband radiometers. Dr. Sonja Behnke (Los Alamos National Laboratory) will partner with NASA MSFC to advance the radio frequency payload for a 3D lightning geolocation capability with a constellation of CubeSats. This technology could provide the first 3D global scale observations of lightning from space, which would enable advances in the knowledge of thunderstorm structure, dynamics, and cloud microphysics, as well as the morphology of lightning within the changing climate.

Also, ESTO is pleased to announce that 8 of the 12 Principal Investigators are new to the technology program.

71 proposals were evaluated through the ACT-20 solicitation process, and funding for the 12 selections is expected to total nearly $14 million over a three-year period. The new ACT awards are as follows:



W-Band RF-Photonics Receiver for Compact Cloud and Precipitation Radars
Razi Ahmed, Jet Propulsion Laboratory

Climate and weather models depend on space-borne satellite measurements of clouds and precipitation over fine temporal scales (order of minutes). Current low Earth orbiting (LEO) weather satellites are limited in number and are thus unable to provide data with the necessary temporal resolution. A constellation of cloud profiling instruments in LEO would provide this essential capability, however, new instrument architectures, compatible with low-cost satellite platforms, such as CubeSats and SmallSats are needed to enable such missions. W-band radars operating at 94 GHz are particularly attractive for studying clouds because of greater sensitivity of millimeter-waves to cloud particles and the significant reduction in instrument size at W-band.

We propose to develop the first RF-photonics radar receiver subsystem to enable the next generation of ultra-compact millimeter wave radars suitable for cloud and precipitation profiling, planetary boundary layer observation, altimetry and surface scattering measurements. The improved RF-photonics architecture was first proposed for a different application, here we propose to adapt the concept specifically for a W-band (94GHz) radar, which is generally assessed to be the primary means for observing clouds in the free troposphere as well as planetary boundary layer from space. The radically different receiver architecture offers the following advantages with respect to a typical W-band RF receiver: 1) reduced number of components and interfaces and therefore reduced size, weight and power (SWaP) requirements, 2) lower system noise (and therefore improved sensitivity), 3) integrated generation of high quality 94 GHz reference frequency (and therefore reduced ground clutter contamination over the desired cloud echoes when paired with a highly linear and low phase noise amplifier). Any one of these advantages is highly desirable form a systems point of view, however a device with all these characteristics will be a true game changer for earth observing W-band radars on resource constrained platforms.

During this project we will advance the state-of-the-art of Whispering Gallery Mode (WGM) resonators for W-band applications using numerical simulations and lab experiments. We will also design, build and test a high-performance W-band LO. We will fabricate and package the photonics receiver and LO, and characterize its performance (system temperature, input power tolerance, gain, linearity, dynamic range etc.) over various temperature conditions and integrate in a W-band radar test-bed and compare with traditional receiver architectures to demonstrate the feasibility and advantages of the novel RF-photonics approach.

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Photonic Lantern Interferometric Receiver for Remote Sensing Applications
Rodrigo Amezcua Correa, University of Central Florida

Objectives and Benefits: A key strategic challenge for Earth Science Measurements in the era of large-scale atmospheric high spectral resolution aerosol lidar (HSRL), trace gas, and wind lidar systems is the lack of robust low cost, small size, low maintenance optical spectral discrimination components. Both high resolution aerosol, wind lidar, and trace gas mapping will continue to be scientifically crucial for responding to the challenge of climate and environment change, and for a broad range of science disciplines, including understanding planetary boundary layer processes, radiation balance, and hazardous weather events to mention a few. As noted in the National Academies 2017-2027 decadal survey for Earth science and applications from space (“ESAS 2017”), wind and aerosol observations are identified in three of the “Targeted Observable” themes. However, traditional bulk-optic HSRL and direct detection wind lidar components are very sensitive to misalignment, and require additional arrangements to either actively maintain alignment or specially designed thermally stabilized passive structures in an attempt to preserve the quality of the interference signal. This is especially challenging for spaceborne lidar interferometer components that are subjected to extreme vibration and thermal conditions prior to operational space measurements and represents a major risk factor. In addition, both bulk-optic active and passive systems add weight and size that is also undesirable. The objective of this proposal is to exploit innovative photonic component technology to develop an all-fiber telescope to detector architecture for a high spectral resolution lidar (HSRL) that can be extended to wind, trace gas lidar systems. This approach will significantly reduce optical alignment risk, size, and weight compared to traditional bulk-optics schemes. Our approach embraces the photonic lantern concept to transform the complex spatial and angular light pattern at the telescope field stop into multiple diffraction limited beams so fiber Bragg grating (FBG) spectral filters, and other single-mode components can be exploited in the detection process. The use of these notions in lidar receivers represents a transformational technology for lidar receiver architectures that traditionally cannot use single mode fiber components.

Outline of Proposed Work and Methodology: Our inter-disciplinary team will leverage UCF’s CREOL photonics component expertise with NASA Langley’s heritage in aircraft and space borne lidar systems. The work proposed here will apply optical waveguide theory to photonic lantern design and fabrication and FBG development leading to prototype system testing. High efficiency photonic lanterns will be designed using finite-element and beam-propagation methods. CO2 laser glass processing equipment and custom low index glass capillaries will be used for photonic lantern manufacturing. FBG writing will be performed using adaptive optics UV interferometry. These efforts will be continually integrated with lidar group Co-Investigators providing refinement to our receiver approach and with simulations/theory guiding device development and experimental activities. The team will develop an atmospheric lidar performance model incorporating the expected optical characteristics of the novel photonic lantern/FBG lidar receiver to provide design considerations on various application scenarios. Tests of the photonic lantern receiver in a configuration to obtain atmospheric demonstration measurements will be conducted. Laboratory and any atmospheric data collected will be evaluated for HSRL aerosol Mie/Rayleigh scattering discrimination. Results will be used to advance applications for a variety of aircraft and satellite lidar systems. This work will be carried out over a 3-year duration, entering at TRL-2 starting with a technology concept and existing at TRL-4 with a component validation in a laboratory environment.

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Advancing the Radio Frequency Payload for a 3-D Lightning Geolocation Capability with a Constellation of CubeSats
Sonja Behnke, Triad National Security, LLC

CubeSpark is a new CubeSat mission concept is under development by NASA Marshall Space Flight Center (MSFC) and Los Alamos National Laboratory (LANL) to make detailed 3-dimensional (3-D) measurements of lightning on a global scale, which would yield transformational information about the structure of thunderstorms. CubeSpark will use a small constellation of CubeSats in low Earth orbit, to make combined radio frequency (RF) and optical measurements of lightning. Each CubeSat will be equipped with an RF payload that would independently detect and record impulsive radio emissions from lightning; the synthesis of these measurements, coupled with complementary onboard optical lightning mapping observations, would provide the latitude, longitude, and most critically, altitude of the numerous individual lightning components that comprise a lightning flash. The result would be a map of the 3-D structure of a lightning flash. This 3-D structure is intimately linked to the precipitation and vertical motions of a thundercloud; thus, lightning observations are a powerful tool that can provide insight into the microphysical and dynamical processes of severe storms. CubeSpark would enable these measurements to be sampled from all over the globe over the course of many orbits, giving a rich data set covering many different environments, which is the key to understanding the underlying physical processes of storms.

The satellite-based RF global 3-D lightning geolocation capability has been proven with operational LANL-designed RF payloads on GPS satellites in support of nuclear treaty monitoring missions; however, at medium Earth orbit the signal to noise ratio is much smaller than it would be from the low Earth orbit of CubeSpark. Additionally, the RF 3-D lightning mapping technique is also commonly used in ground-based arrays, but the range of those sensors is limited to only a few hundred kilometers. By contrast, global, optically based lightning mapping from space has been proven by MSFC’s Optical Transient Detector (OTD) and Lightning Imaging Sensor (LIS) instruments, but alone these measurements can only resolve lightning structure in 2 dimensions (latitude and longitude). By combining RF and optical lightning mapping measurements, not only do we add the altitude information essential for understanding the structure of thunderstorms, but we can also resolve lightning flashes in higher detail than with either capability alone. Thus, from low-Earth orbit, CubeSpark will provide unique dual-phenomenology 3-D measurements of lightning that will give critical insight into global thunderstorm processes. These data are important to the NASA Earth Science focus areas of Weather, Atmospheric Composition, and Climate Variability and Change, and are highly relevant to the most recent Decadal Survey.

LANL has decades of experience in the development of RF payloads on satellites for nuclear treaty monitoring, while MSFC has extensive experience in making global observations of thunderstorms from space. In order to advance the CubeSpark concept, components from existing RF payload designs need to be miniaturized for the size, weight, and power requirements of a CubeSat. We will leverage LANL’s expertise to modify the analog and digital components of the RF receiver and the amplifier for an active antenna, while MSFC will establish rigorous lightning measurement requirements that the new components will meet. The receiver and amplifier components for CubeSpark are currently at TRL 2. The proposed work to increase this TRL includes 1) identifying new subcomponents that will reduce size, weight and power of the component; 2) producing prototypes of the new components, which includes component design, layout, fabrication and assembly; and 3) initial laboratory hardware tests to verify basic functionality, power consumption and performance. This work, which is critical for enabling the CubeSpark mission, will advance these components to TRL 4.

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A Compact, High-Power 167-174.8 GHz Traveling-Wave Tube Amplifier for Planetary Boundary Layer Differential Absorption Radar
Kenneth Kreischer, Northrop Grumman Systems Corporation

Our objective is to develop a 100 W traveling-wave tube (TWT) amplifier that is tunable from 167 to 174.8 GHz to enable spaceborne profiling of planetary boundary layer (PBL) water vapor in cloudy and precipitating volumes using differential absorption radar (DAR). Such measurements are inaccessible by any current remote sensing method, and directly address the PBL targeted observable outlined in the 2017 Decadal Survey, which called for technology incubation to enable profiling of PBL water vapor and temperature from space with 200 m vertical resolution. Global-scale, high-resolution measurements of PBL thermodynamics are essential in order to improve the representation of unresolved PBL processes in climate and weather models, with impacts to several high-value science questions including low-cloud climate feedbacks and severe weather predictability. The TWT amplifier is a key component in the envisioned architecture for a spaceborne DAR that is capable of sensitively detecting clouds in a variety of cloudy PBL scenes while satisfying the 200 m vertical resolution requirement for humidity profiles. Therefore, we propose to advance the Technology Readiness Level (TRL) from 2 to 4 of a TWT-based high-power amplifier module that meets the requirements for spaceborne DAR operation. This work builds on technology heritage at Northrop Grumman Mission Systems in compact, high-power vacuum source development at millimeter and submillimeter-wave frequencies, and at the Jet Propulsion Laboratory (JPL) in DAR instrument development and measurement validation through the Vapor In-cloud Profiling Radar (VIPR, IIP-16 and AITT-19) project.

The TWT-based high-power amplifier proposed here represents a state-of-the-art, compact solution to the problem of efficient high-power generation at unconventionally high radar frequencies. The TWT design will be based on a proven narrowband component at 233 GHz developed for a DARPA-initiated airborne radar program, but under this effort significant innovations will be incorporated into the source design to make it specifically relevant to deployment in an orbital DAR system. Relative to previous G-band high-power amplifier modules, this subsystem will feature a 10x reduction in both volume and mass, achieved by using a periodic permanent magnet instead of a solenoid to confine the vacuum source electron beam; the TWT circuit design will have higher gain to ensure 100 W operation despite lower available input power levels from solid-state 167-174.8 GHz drive sources; and the cathode high-voltage supply will be able to switch at the microsecond time scale between two states in order to tune the TWT center frequency between the online (174.8 GHz) and offline (167 GHz) DAR frequencies at a rate much faster than the radar pulse repetition frequency. During the first two years of this three-year effort, multiple TWT amplifier prototypes will be designed, fabricated, and evaluated to ensure that the final integrated module meets the performance requirements of 100 W output power, 25% duty cycle, 5% tuning bandwidth, and 10 kHz frequency-switching speed. In the final year, the VIPR system will serve as a testbed for verifying the TWT performance in realistic atmospheric measurement scenarios and for demonstrating its in-cloud profiling capability.

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Ultra-Wideband Photonic Spectrometer for PBL Sensing
Thomas Dillon, Phase Sensitive Innovations, Inc.

Within the Planetary Boundary Layer (PBL) most of the Earth’s energy exchange occurs, yet remote sensing observations of the PBL are severely lacking. PBL is notoriously difficult to measure via traditional measurement techniques. The key to PBL characterization is maximizing spectral information to enable accurate atmospheric retrievals near the PBL. For a space-based microwave radiometry application, much narrower channel widths over much wider overall bandwidths are desired in order to measure the upwelling microwave radiance of the sky over varying PBL depths and shapes. Channel widths of 1 GHz or less are desirable over 40-50 GHz bandwidth in order to increase altitude resolution of microwave sounders.

To improve our understanding of PBL phenomenon, we will develop an advanced arrayed waveguide grating (AWG) device based on photonic integrated circuit (PIC) technology, which we’ll use to construct an RF photonic spectrometer for a millimeter wave radiometer back-end. The high spectral resolving power of the AWG will enable unprecedented sampling and wideband operation for improved retrieval accuracy across the temperature and humidity sounding bands, allowing never achieved before ability to spectrally resolve the shape and magnitude of the sounding channel lines.

The AWG is a dispersive integrated photonic device commonly employed to spectrally separate optical signals in telecommunications applications. Commercial devices are available with typical channel widths in the range of 50 to 200 GHz. In partnership with Sandia National Lab and JPL we propose a silicon based photonic AWG that allows channelization of a 40 GHz RF bandwidth into less than 1 GHz channels in a compact footprint. Sandia National Labs has recently demonstrated a silicon photonic arrayed waveguide grating that allowed channelization of an 11 GHz RF bandwidth into 1 GHz channels in a compact (1.1 cm2) footprint. The high index contrast of silicon waveguides allows for tight waveguide bends which enables this compact footprint. To achieve high cross-talk suppression, we will combine this technology with active tuning of the optical phase of each waveguide, using integrated thermal phase shifters. The resultant technology will provide capabilities to perform microwave spectrometry over unprecedented bandwidths in a small form-factor and extremely low power.

PSI has developed high speed, electro-optic phase modulators as a core product, with extremely wide bandwidth operation from DC to 500 GHz, limited only by test capability. By using these modulators to “optically upconvert” millimeter wave signals, we have demonstrated passive, video-rate W-band imaging receivers using optical back-end processing for real-time image reconstruction. Our modulator provides the bridge between the RF front-end and the spectrometer back-end, converting RF signals in the range of 118 – 183 GHz to optical signals for processing and detection. The upconversion is efficient and low-noise, and allows powerful coherent processing to be performed with optical lenses and filters. We possess considerable experience implementing phase locking techniques for such coherent optical systems, which we’ll leverage to provide phase locking and phase tuning of the arrayed waveguide grating and thus generate the desired filter functions for the spectrometer.

JPL through its Micro Devices Laboratory will lend its expertise in testing the Photonic chip. JPL will also perform system integration and testing with a front-end low noise 183 GHz radiometer HAMSR as well as phase modulator. Testing will also involve upward looking atmospheric sounding using the wideband photonic spectrometer. JPL has a long and successful heritage in millimeter wave radiometry, and has several low noise millimeter wave radiometers in lab such as HAMSR, GeoSTAR, and MASC.

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Visible to SWIR Fast eAPDs for Panchromatic FTS Instrument
Arvind D’Souza, DRS Network & Imaging Systems, LLC

This proposal focuses on advancing sensors used for air quality forecasting by observing ozone and trace gases via imaging spectrometers such as the Panchromatic Fourier Transform Spectrometer (PanFTS) instrument. Solar reflected radiances of these trace molecules vary over 2 orders of magnitude between 350 nm to 2500 nm wavelength range, and over high and low albedo scene variations. Typically, two or more imaging spectrometers are required to do these measurements. An imaging spectrometer generally has either large dynamic range or small flux sensitivity, but not both. To reduce system Size, Weight and Power (SWaP) and cost, we propose a large dynamic range Focal Plane Array (FPA) with an in-flight programmable 1 – 300x gain, capable of observing combined ozone, water vapor, CO, NO2, methane, and N2O in one imaging spectrometer.

We propose to hybridize a high dynamic range 16-bit Digital ROIC (DROIC) with an electron avalanche photodiode (eAPD) FPA. The eAPD feature enables us to adjust the gain and effective least significant bit (LSB) continuously over 2+ orders of magnitudes, vs the binary high and low gain settings (~10x) of a traditional FPA. This eAPD technology was invented for Astrophysics Science and we will extend this technology to Earth Science applications and our wavelength range. The eAPD gain is in-flight programmable, which enables a broadband imaging Fourier transform spectrometer to adjust its flux sensitivity over the UV-to-SWIR wavelength range when measuring different species.

The detector proposed is a significant advancement in the development of eAPD FPAs for JPL’s PanFTS instrument, where the FPA needs to run at 1 kHz frame rate. This task leverages existing eAPD FPAs used on other NASA programs. However, the existing eAPD FPA’s cut-on wavelength starts at 800 nm, due to the CdTe buffer layer through which photons have to transduce prior to reaching the HgCdTe absorber layer. This task extends eAPD cut-on wavelength into visible and/or UV wavelength range, which requires removal of the GaAs substrate and the CdTe buffer layer. The most challenging portion of the project is the development of a passivation layer at the illuminating surface that transmits photons between visible and/or UV wavelength range to 2500 nm, while minimizing surface recombination velocity at the surface to maintain low dark current at 120 K. Our baseline is to demonstrate an eAPD FPA with 500 nm cut-on wavelength,
with a goal of extending the cut-on wavelength into the ultraviolet (UV) for the ozone measurement.

The FPA will employ a proven 640 x 480 DROIC with 20-micron pixel pitch fabricated in a 65 nm foundry process. The photocurrent from the detector charges the input capacitance of the front-end of the DROIC pixel (~ 1fF) until the voltage trips a comparator which produces a pulse and resets the input. The front-end is configured to accommodate both n-on-p and p-on-n detector polarities and can be switched on command. The pulse corresponds to an LSB that can be varied from 1000 to 2300 e-. These pulses trigger a 16-bit ripple counter that can be globally set for up/down operation which is useful for some operating modes. Integration time is set by stopping the counters at the specified interval, not by resetting the detector capacitance as in an analog readout.

The first year of the program includes the detector design, material growth of eAPD wafers, processing of detector arrays, characterization of test arrays and test hardware prep for the digital FPAs. The second year will be the hybridization of eAPD detector arrays to digital ROICs, integration and assembly of the digital FPAs into the prototype instrument followed by test. Entry level for this technology is TRL2; exit level TRL at the end of the program after two years will be TRL4. Upon completion, this effort will enable smaller, lighter instruments with lower power consumption capable of addressing Atmospheric Composition focus area.

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Bandstructure Engineered Type-II superlattice Antimonide Avalanche Photodiodes (BETA-APD) for Space Lidar Instruments
Sanjay Krishna, Ohio State University

The goal of this Advanced Component Technology (ACT) proposal is to develop next-generation detectors using emergent antimonide superlattice technology for space lidar instruments in support of ESTO’s mission of measuring natural earth phenomenon, crossing most of the Focus Areas outlined in the 2017 Decadal Survey. Primary applications will include swath mapping and vegetation profiles, but the detectors can be used for many other science applications, including atmospheric backscatter and absorption measurements. There is a need for new lidar detectors with high quantum efficiency, sensitivity and dynamic range. Recently, HgCdTe avalanche photodiode (APD) arrays have provided a major breakthrough in space and airborne lidar detectors with high quantum efficiency, low dark current, high multiplication gain and low excess noise factors. However, these detectors need to be cooled to low temperatures (~100K) because the dark current increases at higher temperatures and becomes unstable. Moreover, production of detectors based on II-VI alloys is hampered by low yield, limited fabrication of large format arrays, and high cost.

A team of scientists and engineers from academia (The Ohio State University/University of Illinois Chicago), small business (SK Infrared LLC), and a NASA center (Goddard Space Flight Center) propose to develop novel Bandstructure Engineered Type-II superlattice Antimonide (BETA) APDs using mature III-V semiconductor materials on InP substrates. The proposed approach will remove the need for cryogenic cooling and provide a manufacturable path using III-V compound semiconductor foundries. The project will combine robust theoretical and experimental research and development to demonstrate small format (4×4) linear-mode APD arrays with the goal of operating at T > 240 K with a 50% cut-off wavelength > 2.05 micron. This cut-off wavelength will support a variety of lidar systems based on fiber lasers operating at 1.03, 1.55, and 2 micron. The target specifications for the APD will be a high multiplication gain, low excess noise factor and low dark current density at the operating bias. The key innovation is to separately engineer the electron and hole impact ionization coefficients using strained layer superlattices and digital alloys of III-V quaternary semiconductors on InP substrates. The final deliverable will be a functioning small format array that is demonstrated at high operating temperatures and tested in a laboratory environment (TRL 4). The technical plan focuses on rapid iterations of modeling, material growth, device fabrication, and characterization of multiplier as well as separate absorption and charge multiplication candidates to demonstrate the desired performance goals. This technology can be rapidly transitioned to large format focal plane arrays beyond the scope of this ACT project to support the development of new lidar instruments with capabilities that greatly exceed the current state of the art. Therefore, the proposed technology will be disruptive because it enables operation close to room temperature, which will lead to a reduction in the size, weight, power consumption, risks, cost, and development time of future Earth remote sensing systems.

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Radar on a Chip
Lute Maleki, OEwaves Inc.

Technical area and Objectives:
This proposal is a collaboration between OEwaves, UC-Davis, and NASA Goddard for design, development, and demonstration of a radar on chip based on photonics technology. Recent demonstration of a high performance widely tunable photonic local oscillator (LO) at OEwaves is the basis for an architecture to realize a radar receiver/transmitter system on a photonic integrated circuit (PIC). Photonic Integrated Circuit (PIC) technology provides the most competitive opportunity to reduce the size, weight and power (SWaP) for future generations of multi-frequency radars and wideband radiometers, which are the most effective sensors for measuring key parameters in the Earth’s atmospheric composition, hydrological cycle, and surface deformation and changes. Our vision is to tailor this technology for cloud (W-band) and precipitation (Ku-/Ka-band) radar, active and passive water vapor measurements (G-band), active atmospheric pressure radar (V-band), and passive temperature sounding (V-band).

The proposed architecture consists of two ultra-narrow linewidth lasers to generate the LO via photo-mixing on a photodetector. The carrier frequency is set by the frequency interval difference of the two lasers. By modulating the light output of one of the lasers the waveform of interest will be imprinted on the (microwave) carrier. This microwave output of the detector will be amplified and introduced to the antenna for transmission. The received microwave signal will be used to modulate the laser light before photo-mixing with LO in a second photodetector for production of the baseband signal, which can subsequently fed to the digital signal processing subsystem of radar.

There are several unique benefits of this architecture:1) Ultra-narrow line lasers result in generation of highly spectrally pure microwave carriers, beyond what is achievable with electronic oscillators; 2) it can operate in coherent or direct detection mode with any waveform of interest; 3) heterogeneous chip integration significantly reduces size, weight and power by multiple orders of magnitude; 4 ) compatibility with semiconductor manufacturing process significantly reduces future production costs; 5) any frequency between 10GHz- 350 GHz can be supported for operation, limited only by the bandwidth of the photo-mixer and the high power amplifier, and the antenna; 6) a PIC radar transmitter/receiver supports the work already underway at NASA for realization of a low SWAP phased array radar for ultimate application on all space vehicles, including mini – satellites.

In this project we propose developing a PIC for coherent frequency up-/down-conversion compatible with operating frequencies up to W-band. This device would replace multiple radar components providing improved performance and significantly reducing size, weight, power, and cost (SWaP-C) by removing the need for multiple RF phase-locked oscillators, multipliers and mixers. The PIC will operate on a probe station with external drive electronics, amplifiers and antenna to demonstrate its functionality and verify its performance.

The collaboration includes system design and integration and components tests by OEwaves, chip design and fabrication and fabrication of the radar PIC at UC-Davis, and system Test and verification of performance at Goddard. This concept will begin at TRL level 1-2, and will end at TRL3-4, at the end of the three-year (36 months) program.

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Miniaturized Microwave Absolute Calibration (MiniMAC) for Sounders and Imagers on SmallSat and CubeSat Platforms
Steven Reising, Colorado State University

Successful demonstration of the Temporal Experiment for Storms and Tropical Systems Technology Demonstration (TEMPEST-D) mission has proven that microwave imagers and sounders on CubeSats are capable of well-calibrated, stable, low-noise observations. For 22 months, TEMPEST-D has successfully performed global passive microwave observations at 5 frequency channels from 87 to 181 GHz, focusing on clouds, precipitation and humidity profiling. Additionally, the Tropospheric Water and Cloud Ice (TWICE) IIP-13 task successfully demonstrated a multi-frequency, wide-band millimeter/sub-millimeter wave instrument measuring at 16 frequencies from 118 to 850 GHz with size, weight and power for 6U CubeSat deployment. TWICE science goals focus on ice cloud particle size and humidity & temperature profiling, key for the NASA Earth Science strategic areas of Climate Variability and Change and Weather. TWICE was selected for feasibility studies for Aerosols, Clouds, Convection and Precipitation (ACCP) in the 2017 NAS Earth Science Decadal Survey.

A combined version of the water vapor profiling channels of TEMPEST-D and the temperature profiling channels of TWICE is ideal to address NOAA’s goals for next-generation LEO weather satellite systems. NOAA envisions a new generation of operational LEO constellations of small satellite sensors, to provide global coverage with 2-3 hour repeat times. Advantages of small satellite constellations include: (1) increased temporal sampling globally; (2) reduced cost and scalable sensor deployment depending on available resources, launch opportunities and satellite longevity; and (3) capability for rapid infusion of new technology.

To accomplish a well-calibrated small satellite constellation, we envision one microwave sounder with SI-traceable brightness temperature calibration, complemented by many lower-cost small satellites with microwave sounders to accomplish 2-3 hour sampling. In collaboration with NIST and Duke University, we propose a three-year task to develop a NIST-traceable Miniaturized Microwave Absolute Calibrator based on metamaterials on organic-based printed-circuit boards (PCBs) at millimeter-wave sounding channels from 50 to 220 GHz.

Metamaterial-based microwave absorbers fabricated on thin, organic-based PCBs hold promise for microwave sounders on CubeSats. The thin, conformal surface represents a significant weight improvement in ferrite-loaded epoxy absorbers and provides a uniform physical temperature for improved calibration accuracy. Commercial vendors supply multilayer PCBs with core thicknesses less than 25 microns with moderate permittivity and low dielectric loss tangents.

Currently, these thin substrates are used in high-speed digital and mixed-signal applications, but good microwave properties have recently been demonstrated well above 200 GHz. A critical task is to develop a metamaterial pattern capable of broadband operation at millimeter-wave sounding channels from 55 to 220 GHz. This task will be carried out through both analytical and numerical modeling, and results will be supported by fabricated prototypes and experimental validation. The metamaterials will be tested in an anechoic chamber at NIST to validate both brightness temperature and reflectance. The entry TRL of the microwave absorbers is 2, and due to testing of these calibration subsystems in a laboratory environment, the exit TRL is 4.

The technologies developed for MiniMAC will significantly benefit the microwave remote sensing community. First, the NIST brightness temperature target will enable SI traceability of various microwave sounding sensors. This will enhance instrument evaluation, increase data repeatability among instruments, and enhance the historical record of microwave sounding data. Second, the physically thin metamaterial absorber will improve system SWaP and physical temperature homogeneity and knowledge for CubeSat microwave calibration targets.

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Stacked Miniaturized And Radiation Tolerant Intelligent Electronics (SMARTIE)
James Yamaguchi, Irvine Sensors Corporation

With the desire of many current and future Space missions to utilize advanced artificial neural networks, high data bandwidth sensors, and perform real-time, on-board automated decisions new technology is needed to make available state-of-the-art compute capabilities. Irvine Sensors proposes a Stacked Miniaturized And Radiation Tolerant Intelligent Electronics (SMARTIE) technology that uses advanced packaging to integrate three, high performance, compute tiles into a folded-flex module consisting of an off-the-shelf multi-core processor, graphics processing unit (GPU), and memory; and combines these together with a system controller providing adaptive redundancy, background data management, and inter-tile communication to mitigate radiation effects. Each compute tile consists of a SnapDragon 855 system-on-chip, low power DDR4 with built-in ECC, and MRAM with side-channel access for data scrubbing, synchronization, and triple-modular redundancy support. The compute tiles are connected using an adaptive redundancy controller that provides the system with the capability of instantly enabling redundancy across compute tiles for critical computations or exploiting the redundant modules for peak compute power. Non-volatile MRAM reduces start-up and shut-down cycles of each compute tile to provide very high peak compute capabilities for extremely intensive, real-time decision algorithms while consuming minimal average power. Each compute tile achieves performance of over 100GFlops processing capability, nearly 2TFlops of FP16 GPU performance, and 7TOPS of AI engine compute consuming less than 10W.

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Advanced SAPHIRA HgCdTe APD Arrays for NASA Space Lidar Applications
Guangning Yang, NASA Goddard Space Flight Center

In its 2017 Earth Science Decadal Survey report, the National Academy of Sciences recommended that NASA conduct missions to acquire data for nine Explorer- and Incubation-class observables. A next generation lidar system being developed at Goddard Space Flight Center, the Concurrent Artificially-intelligent Spectrometry and Adaptive Lidar System (CASALS), will be able to acquire data for five of these nine: terrestrial ecosystem structure, ice elevation, snow depth and water equivalent, surface topography and vegetation structure, and the surface-atmosphere boundary layer. The CASALS lidar will have a fast wavelength scanning transmitter which can position the laser beam at 960 footprint locations scanned across a 5.8 km wide swath. The 960 footprint locations on the ground will be mapped to an HgCdTe APD array detector in the lidar receiver. At any time, the lidar can arbitrarily point at tens to hundreds of the 960 possible footprint locations by wavelength tuning. At the receiver, to cover all 960 locations, a large linear detector array with close to 100% fill factor is required. We are demonstrating the scanning concept using a linear APD array developed by DRS in collaboration with Goddard. However, its small number of pixels (30 in the current device) and small fill factor (14%) are insufficient for full implementation of the wide-swath mapping. The detector capability is CASALS’s limiting performance factor. To overcome this limitation, we propose a planar linear array HgCdTe APD detector with 100% fill factor. This APD array will have a large array size (320 pixels), high APD gain (>300), high speed (~350MHz), low dark current (<1fA/pixel/rtHz) and high quantum efficiency (~70%). The final packaging of the device will have a matched transimpedance amplifier array, one per detector cell, inside the silicon fan-out underneath the HgCdTe APD chip. The amplifier will have bandwidth matching that of the HgCdTe APD with low noise (~1.5 pA/rtHz).

The proposed device is based on the Leonardo SAPHIRA HgCdTe 320×256 planar APD imaging array developed for astronomy. Our initial test results under ESTO QRS-17 have demonstrated performance with very low dark currents, 1ns pulse response time and greater than 70% quantum efficiency in the near infrared spectral range. This detector will provide a significant performance advance for future NASA space lidar, including the CASALS 3D imaging lidar and CO2 and CH4 trace-gas lidar for Earth and planetary remote sensing, as well as hazard avoidance imaging lidar for NASA landers.

We propose a three-year work program with the first two years concentrating on assessing, adapting and optimizing the Leonardo detector technology development. In Year 3, we will assess the performance of a delivered detector array at Goddard and demonstrate its performance with the CASALS instrument. Our entry TRL is estimated to be at 2 and we expect to exit at TRL 4.

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Hyperspectral Imaging on Photonic-Integrated-Circuits for Future GeoCARB Missions
Ben Yoo, University of California, Davis

We propose to pursue very compact and integrated hyperspectral imagers for future NASA GeoCARB missions covering 0.76, 1.61, 2.06, and 2.32 micron wavelength bands to achieve observation of the concentrations of carbon dioxide, methane, carbon monoxide and solar-induced fluorescence of the earth at extremely high sensitivity and high spectral resolutions while occupying extremely small size, weight, and power (SWaP). The proposed hyperspectral imagers utilize 3D photonic integrated circuits consisting of strongly dispersive photonic components to spectrally resolve the greenhouse gas lines while offering high spatial resolution supported by wafer-scale baselines. Extremely sensitive avalanche photodetector (APD) arrays achieve detection at low light levels, thanks to the internal photomultiplication gain available within the photodetector elements. In addition, we will introduce innovative compressive imaging techniques to achieve high-resolution hyperspectral imaging in the spectral and spatial domains utilizing very compact standard 2D readout circuits, realizing 100x reduction in both the number of detector pixels and the amount of data transmission. NASA’s currently planned GeoCARB missions utilize Lockheed Martin’s Tropospheric Infrared Mapping Spectrometers (TIMS) consisting of relatively large bulk optics, while the proposed hyperspectral imaging exploits 3D photonic integrated circuits with APD arrays for compressive imaging of simultaneous spectral and spatial imaging. The proposed project aims at realizing the new compressive hyperspectral imaging subsystem with 100x-1000x reduction in SWaP, 100x-1000x reduction in measurement time, and 100x less amount of data transfer communications compared to the specifications of the currently planned NASA GeoCARB mission using TIMS.