This PDF file contains the front matter associated with SPIE Proceedings Volume 11131 including the Title Page, Copyright information, Table of Contents, Introduction, and Conference Committee listing.

The second generation Tiny Ionospheric Photometer (TIP) is a compact, high-sensitivity, nighttime ionospheric photometer designed for small satellites. TIP launched February 19, 2017 to the International Space Station as part of the GPS Radio Occultation and Ultraviolet Photometry—Colocated (GROUP-C) experiment to test advanced sensing objectives. The TIP optical design improves upon previously-flown photometers and employs a filter wheel to measure signals. The third generation sensor is a 1U Cubesat-compatible Triple Tiny Ionospheric Photometer (Tri-TIP), manifested to fly on the dual 6U Coordinated Ionospheric Reconstruction CubeSat Experiment (CIRCE) in early 2020. The Tri-TIP design builds upon several technologies demonstrated aboard TIP, but utilizes a beam splitter to simultaneously monitor signal, red-leak, and background signals. This paper compares the pre-flight and on-orbit performance of TIP with pre-test theoretical results for Tri-TIP.

Cloud ice play important roles in Earth’s climate and weather systems through their interactions with atmospheric radiation, dynamics, energy and precipitation processes. Submillimeter (submm) wave remote sensing at 200-1000 GHz is able to provide the sensitivity not covered by visible (VIS)/infrared (IR) and low-frequency microwave (MW) sensors (10-183 GHz), and measure cloud ice in the middle-to-upper troposphere. The IceCube 883-GHz cloud radiometer is the latest of NASA’s efforts to advance the technology readiness level (TRL) of submm-wave receiver technology for future compact, low-cost implementation of Earth observing systems. Emerging CubeSat opportunities allow a fast-track development and spaceflight demonstration of IceCube on a 3-U CubeSat. Funded by NASA’s In-Space Validation of Earth Science Technologies (InVEST) program and Science Mission Directorate (SMD), IceCube is the first CubeSat developed and flown by Goddard Space Flight Center (GSFC) in 2.5 years, using commercial off-the-shelf (COTS) components and subsystems. It was successfully released from International Space Station (ISS) in May 2017, acquired 15-month science data and produced the first global map of the 883-GHz cloud ice. It achieved all mission objectives and provided a pathway for future cost-effective cloud observations from CubeSat constellation.

Accurate, long-term solar spectral irradiance (SSI) measurements are vital for interpreting how solar variability impacts Earth’s climate and for validating climate model sensitivities to spectrally varying solar forcing. The Compact Spectral Irradiance Monitor (CSIM) 6U CubeSat successfully launched on Dec. 3rd, 2018 as part of the SpaceX SSO-A: SmallSat Express Mission ultimately achieving a sun-synchronous 575 km orbit. CSIM brings new, emerging technology advancements to maturation by demonstrating the unique capabilities of a complete SSI mission with inherent low mass and compact design. The instrument is a compact, two-channel prism spectral radiometer incorporating Si, InGaAs, and extended InGaAs focal plane photodiodes to record the solar spectrum daily across a continuous wavelength region spanning 200 – 2800 nm (>97% of the total solar irradiance). A new, novel electrical substitution radiometer (ESR) using vertically aligned carbon-nanotube (VACNT) bolometers serves as an absolute detector for periodic on-orbit spectral calibration corrections. Pre-launch component level performance characterizations and final instrument end-to-end absolute calibration achieved low combined standard uncertainty (u_c<0.5%) in irradiance. These calibrations were performed in the LASP Spectral Radiometer Facility (SRF), a comprehensive spectral irradiance calibration facility utilizing a tunable laser system tied to an SI-traceable cryogenic radiometer. On-orbit, optical degradation corrections to better than 0.05% / year uncertainty are achieved by comparing periodic, simultaneous solar measurements of the two CSIM channels operating with significantly different solar exposure duty cycles. Operational overlap of CSIM with existing SSI measurements validate concepts for maintaining critical long-term solar data records.

RainCube (Radar in a CubeSat) is a technology demonstration mission to enable Ka-band precipitation radar technologies on a low-cost, quick-turnaround platform. The 6U CubeSat, features a Ka-band nadir pointing precipitation radar with a half-meter parabolic antenna. RainCube first observed rainfall over Mexico in August 2018 and in the following months captured the distinct structures of a variety of storms as well as characteristic signatures of Earth’s surface essential to diagnose pointing and calibration. In this presentation we will focus on the characteristics of the observed scenes, specifically to convey the potential, as well as the limitations, of a radar of this class in addressing the goal of observing weather processes from space.

To improve understanding of rapid, dynamic evolution of convective cloud and precipitation processes as well as the surrounding water vapor environment, we require fine time-resolution multi-frequency microwave sounding observations capable of penetrating inside the storm where the microphysical processes leading to precipitation occur. To address this critical observational need, the Temporal Experiment for Storms and Tropical Systems (TEMPEST) mission deploys a train of 6U CubeSats carrying identical low-mass, low-power millimeter-wave radiometers to sample rapid changes in convection and water vapor every 3-4 minutes for up to 30 minutes. These millimeter-wave radiometers observe at five frequencies from 87 to 181 GHz. By rapidly sampling the life cycle of convection, TEMPEST fills a critical observational gap and complements existing and future satellite missions. To demonstrate global, well-calibrated radiometric measurements to meet the needs of TEMPEST, the TEMPEST Technology Demonstration (TEMPEST-D) mission satellite was launched on May 21, 2018 on Orbital ATK’s CRS-9 mission to the ISS and deployed into a 400-km altitude and 51.6° inclination orbit by NanoRacks on July 13, 2018. TEMPEST-D has met all mission requirements on schedule and within budget. After achieving first light on September 5, 2018, the TEMPEST-D mission has achieved TRL 7 for both the instrument and spacecraft systems. TEMPEST-D brightness temperatures have been cross-calibrated with those of four NASA, NOAA and EUMETSAT reference sensors observing at similar frequencies. Results demonstrate that the TEMPEST-D on-orbit instrument is a very well-calibrated and stable radiometer with very low noise, rivaling that of much larger, more expensive operational instruments.

Lunar Ice Cube (LIC) is one of 13 6U cubesats that will be deployed by EM1 in cislunar space. LIC along with Lunar Flashlight and LunaH-Map, all focused on the search for volatiles but with very different payloads, will be the first deep space cubesats designed to address goals for both demonstrating new technologies and collecting scientific data. Effectively, as their developments are occurring in parallel, they are acting as prototypes for future deep space cubesats missions. One useful outcome of this ‘experiment’ is to evolve a working paradigm for the development and operation of compact, cost-capped, standardized (supporting subsystems) spacecraft to serve the needs of diverse user communities. The lunar ice cube mission was developed as the test case in a GSFC R and D study to determine whether the cubesat paradigm could be applied to deep space, science requirements driven missions, and BIRCHES was its payload. Here, we present the design and describe the ongoing development, and testing, in the context of the challenges of using the cubesat paradigm to fly a broadband IR spectrometer in a 6U platform, including a very harsh environment, minimal funding and extensive need for leveraging existing assets and relationships on development, and minimum command and telemetry bandwidth translating into simplified or canned operation and the collection of only essential data.

There has been much recent progress with CubeSat-hosted microwave instrumentation for atmospheric sensing. The Microsized Microwave Atmospheric Satellite Version 2a (MicroMAS-2a), launched on January 11, 2018 and has successfully demonstrated temperature sounding using channels near 118 GHz and humidity sounding using channels near 183 GHz. Building on the MicroMAS-2 successes, the Time-Resolved Observations of Precipitation structure and storm Intensity with a Constellation of Smallsats (TROPICS) mission, selected by NASA as part of the Earth Venture– Instrument (EVI-3) program, will provide nearly all-weather observations of 3-D temperature and humidity, as well as cloud ice and precipitation horizontal structure, at high temporal resolution to conduct high-value science investigations of tropical cyclones. TROPICS will provide rapid-refresh microwave measurements (median refresh rate of approximately 40 minutes for the baseline mission) over the tropics that can be used to observe the thermodynamics of the troposphere and precipitation structure for storm systems at the mesoscale and synoptic scale over the entire storm lifecycle. TROPICS comprises a constellation of six CubeSats in three low-Earth orbital planes. Each CubeSat will host a high performance radiometer to provide temperature profiles using seven channels near the 118.75 GHz oxygen absorption line, water vapor profiles using three channels near the 183 GHz water vapor absorption line, imagery in a single channel near 90 GHz for precipitation measurements (when combined with higher resolution water vapor channels), and a single channel at 205 GHz that is more sensitive to precipitation-sized ice particles. TROPICS spatial resolution and measurement sensitivity is comparable with current state-of-the-art observing platforms. TROPICS flight hardware development is on track for a 2019 delivery with launches anticipated no earlier than 2021.

The Naval Research Laboratory (NRL) has established a Regional Coastal Oceanography with Nanosatellites (ReCON) project which will explore the ability of high-resolution nanosatellites to monitor coastal, estuarine, riverine, and other maritime environments in support of U.S. Navy operations. The project will initially focus on using data from the almost 150+ Planet “Dove” nanosatellites which fly in “flocks” acquiring remotely sensed data from sunlight reflecting off the earth surface. The usefulness of remotely sensed data within our research and operations is determined by the ability to accurately perform atmospheric correction and compute water leaving radiances (Lw), which are then normalized (nLw) and form the basis for the generation of remote sensing reflectance and other inherent and apparent optical property products. These nanosatellites have a single infrared band, although two such bands are typically required to automatically select an appropriate aerosol model during atmospheric correction, prior to estimating nLw. While early in the project, this initial study will assess nanosatellite capabilities to accurately retrieve nLw measurements by specifying the aerosol model selection during the atmospheric correction process. Here we present nLw retrievals for a variety of Planet nanosatellite imagery covering an entire year over a northern island of Venezuela, which covers coastal and open ocean type waters. The nLw retrievals from the nanosatellites using forced aerosol models are compared to coincident nLw retrievals from the Suomi-National Polar-orbiting Partnership (SNPP) Visible Infrared Imaging Radiometer Suite (VIIRS) to gauge the potential reliability and accuracy of using nanosatellite imagery as a competent data source for ocean color optics.

A novel CubeSat payload for atmospheric research has been developed to study the temperature distribution in the mesosphere and lower thermosphere region. The payload consists of a small interferometer for the observation of airglow at 762 nm. Since the rotational structure of the O₂ A-band emission follows the Boltzmann law, the ratio of different emission lines allows for temperature retrieval without the need of a precise absolute radiometric calibration of the instrument. Integrated in a 6U CubeSat, the instrument will perform simultaneous limb measurements between 60 km and 150 km globally. The agility of a CubeSat shall be used to focus the measurements on specific regions from different viewing directions. In order to achieve high spectral resolution and high optical throughput, a spatial heterodyne interferometer was chosen for detecting the rotational structure of the O₂ A-band emission. The utilization of a two-dimensional imaging detector allows for recording these interferograms at various altitudes at the same time. Since this instrument type has no moving parts, it can be built as a solid block which makes it very attractive for atmospheric measurements especially from space. For highly spatially resolved images of the atmosphere in limb view mode, a high-quality front optics, which images the scene onto the refraction gratings of the interferometer, is required. In addition, a detector optics with minimal aberrations is needed to image the gratings onto the focal plane array. The optical design of the interferometer as well as the technical layout of front and detector optics are presented.

cosine Remote Sensing is leading the first ever demonstration of on-board Artificial Intelligence (AI) applied to the combination of hyperspectral and thermal imaging. The sensing device is a miniaturized reflective optical instrument equipped with unprecedented processing capabilities. The European Space Agency (ESA) has contracted cosine Remote Sensing to highly integrate Thermal Infrared (TIR) technologies into a miniaturized Visible-Near-InfraRed (VNIR) hyperspectral imager and to fit the combined spectral channels in a volume of less than two litres. The imager is named HyperScout-2 as it will use the HyperScout-1 platform, that has flight heritage, as building block to further integrate spectral channels. HyperScout-2 is equipped with a hybrid processing platform composed of a CPU, GPU and VPU. The VPU is a state of art vision processing unit developed by Intel and is for the first time flew in space as part of HyperScout-2. HyperScout-2 will enable experimental programs to investigate the use of Artificial Intelligence for a variety of applications in the field of object detection and data inference. The first application that will be run on is cloud screening. HyperScout-2 will be used as in-orbit test-bed to benchmark the performance of such a miniaturized class of systems as well as to perform hands-on investigations to forecast the benefits of combining frequent coregistrated measurements in the VNIR and TIR from nanosatellites, with less frequent but very accurate measurements performed by institutional satellites such as the Copernicus fleet. This initiative is named PhiSat-1 and is part of the ESA EOP initiative to leverage small satellites to foster technology breakthrough developments. This contribution reports on a general description of HyperScout-2 as well as about the fast track program in which is implemented. We will also highlight the way the space asset will be exploited especially regarding the understanding of the potential of small systems deployed within small satellites constellation if integrated into ecosystems made of small and large systems. The PhiSat-1 is implemented as an enhancement of the FSSCat mission in a 6U cubesat based on Tyvak International platform integrating cosine Remote Sensing hyperspectral/thermal system. The cloud screening application is led by cosine Remote Sensing and supported by Sinergise, Ubotica and University of Pisa.

The long-term balance between Earth’s absorption of solar energy and emission of radiation to space is a fundamental climate measurement. Total solar irradiance (TSI) has been measured from space, uninterrupted, for the past 40 years via a series of instruments. The Compact Total Irradiance Monitor (CTIM) is a CubeSat instrument that will demonstrate next-generation technology for monitoring total solar irradiance. It includes novel silicon-substrate room temperature vertically aligned carbon nanotube (VACNT) bolometers. The CTIM, an eight-channel 6U CubeSat instrument, is being built for a target launch date in late 2020. The basic design is similar to the SORCE, TCTE and TSIS Total Irradiance Monitors (TIM). Like TSIS TIM, it will measure the total irradiance of the Sun with an uncertainty of 0.0097% and a stability of <0.001%/year. The underlying technology, including the silicon substrate VACNT bolometers, has been demonstrated at the prototype-level. During 2019 we will build and test an engineering model of the detector subsystem. Following the testing of the engineering detector subsystem, we will build a flight detector unit and integrate it with a 6U CubeSat bus during late 2019 and 2020, in preparation for an on-orbit demonstration in 2021.

The Coordinated Ionospheric Reconstruction Cubesat Experiment (CIRCE) is a joint US/UK mission consisting of two 6U CubeSats actively maintaining a lead-follow configuration in the same low Earth orbit with a launch planned for the 2020 timeframe. These nanosatellites will each feature multiple space weather payloads. From the US, the Naval Research Laboratory will provide two 1U Triple Tiny Ionospheric Photometers (Tri-TIPs) on each satellite, observing the ultraviolet 135.6 nm emission of atomic oxygen at nighttime. The primary objective is to characterize the twodimensional distribution of electrons in the Equatorial Ionization Anomaly (EIA). The methodology used to reconstruct the nighttime ionosphere employs continuous UV photometry from four distinct viewing angles in combination with an additional data source, such as in situ plasma density measurements, with advanced image space reconstruction algorithm tomography techniques. From the UK, the Defence Science and Technology Laboratory (Dstl) is providing the In-situ and Remote Ionospheric Sensing suite consisting of an Ion/Neutral Mass Spectrometer, a triple-frequency GPS receiver for ionospheric sensing, and a radiation environment monitor. We present our mission concept, simulations illustrating the imaging capability of the Tri-TIP sensor suite, and a range of science questions addressable via these measurements.

Ball Aerospace has developed CIRiS (Compact Infrared Radiometer in Space), a versatile multispectral, infraredimaging radiometer with on-orbit calibration capability. CIRiS generates images in three spectral bands between 7.5 um and 13.5 um. On-board calibration employs views to two flat-panel, high-emissivity carbon nanotube calibration sources and a third view to deep space. Image processing capabilities of the single electronics board include frame shifting and co-adding, binning and windowing, all with parameters selectable on orbit. An uncooled microbolometer focal plane enables CIRiS to operate without a cryocooler, thereby eliminating the associated power draw, complexity, and mission-life limitation. Total instrument power consumption measured in vacuum is < 10 Watts, including instrument heater power. A modular architecture that permits independent changes to CIRiS subsystems facilitates customization for Earth and planetary science missions. Constellations of 8 to 12 spacecraft carrying CIRiS instruments achieve global coverage from Low Earth Orbit (LEO) with daily revisit times, and varying spatial resolution. Among the potential Earth Science applications are measurements of evapotranspiration, plant health, volcano activity, sea surface and inland water body temperature, and vertical atmospheric profile of temperature and trace gas concentration. Lunar CIRiS, or “L-CIRiS” is a modified implementation for lunar surface mineralogy and thermophysical measurements from a lander or rover on the Moon’s surface. The present CIRiS flight model has completed all testing in preparation for an upcoming demonstration mission in LEO on a 6U CubeSat.

The HyTI (Hyperspectral Thermal Imager) mission, funded by NASA’s Earth Science Technology Office InVEST (InSpace Validation of Earth Science Technologies) program, will demonstrate how high spectral and spatial long-wave infrared image data can be acquired from a 6U CubeSat platform. The mission will use a spatially modulated interferometric imaging technique to produce spectro-radiometrically calibrated image cubes, with 25 channels between 8-10.7 μm, at a ground sample distance of ~70 m. The HyTI performance model indicates narrow band NEΔTs of <0.3 K. The small form factor of HyTI is made possible via the use of a no-moving-parts Fabry-Perot interferometer, and JPL’s cryogenically-cooled HOT-BIRD FPA technology. Launch is scheduled for no earlier than October 2020. The value of HyTI to Earth scientists will be demonstrated via on-board processing of the raw instrument data to generate L1 and L2 products, with a focus on rapid delivery of data regarding volcanic degassing, land surface temperature, and precision agriculture metrics.

Technological advancements in detectors, cryocoolers, infrared spectrometers and optical materials enables hyperspectral infrared atmospheric sounding in a CubeSat. Legacy instruments such as NASA Atmospheric Infrared Sounder (AIRS) and the Cross-track Infrared Sounder (CrIS) measure the upwelling spectrum to retrieve temperature profiles and atmospheric water vapor. These data are assimilated by National Weather Prediction (NWP) centers worldwide and had significant positive impact to the operational forecasts. NASA and NOAA have sponsored technology demonstration of a hyperspectral IR sounder packaged in a 6U CubeSat at JPL. The instrument is called the CubeSat Infrared Atmospheric Sounder (CIRAS). Like AIRS, CIRAS uses a grating spectrometer that senses spatial information in one dimension and spectral in the other, but CIRAS uses a 2-dimensional Focal Plane Assembly (FPA), while AIRS uses multiple linear arrays to produce one spectrum. For CIRAS, if the dispersion direction is not aligned with the rows and columns of the detectors, spectral and spatial mixing can cause radiometric errors if uncorrected. This paper discusses a method to resample the signals from the detector array while viewing a spectral and spatial calibration source and produce a spectrally and spatially corrected image. The correction, or ‘Electronic Alignment’ can be performed pre-flight during Integration and Test, or in-flight using a combination of on-board and ground processing systems. Results are presented for simulated misalignments and errors consistent with design requirements using real scenes from the legacy sounders. The method works reasonably well with highest errors around sharp absorption features for cold scenes. Residual radiance errors from the simulation can be used in a larger simulation of the retrieval of geophysical parameters from hyperspectral IR instruments.

MISTiC Winds is an approach to improve short-term weather forecasting based on a miniature high resolution, wide field, thermal emission spectrometry instrument that will provide global tropospheric vertical profiles of atmospheric temperature and humidity at high (3-4 km) horizontal and vertical ( 1 km) spatial resolution. MISTiC’s extraordinarily small size, payload mass of less than 15 kg, and minimal cooling requirements can be accommodated aboard an ESPAClass (50 kg) micro-satellite. Low fabrication and launch costs enable a LEO sun-synchronous sounding constellation that would provide frequent IR vertical profiles and vertically resolved atmospheric motion vector wind observations in the troposphere. These observations are highly complementary to present and emerging environmental observing systems, and would provide a combination of high vertical and horizontal resolution not provided by any other environmental observing system currently in operation. The spectral measurements that would be provided by MISTiC Winds are similar to those of NASA’s Atmospheric Infrared Sounder. These new observations, when assimilated into high resolution numerical weather models, would revolutionize short-term and severe weather forecasting, save lives, and support key economic decisions in the energy, air transport, and agriculture arenas–at much lower cost than providing these observations from geostationary orbit. In addition, this observation capability would be a critical tool for the study of transport processes for water vapor, clouds, pollution, and aerosols. Risk reduction investments by NASA ESTO and BAE Systems have supported an airborne demonstration of this hyperspectral observing method from a NASA ER2, as well as laboratory testing of the spectrometer. The purpose of these airborne tests is to examine the potential for improved capabilities for tracking atmospheric motion-vector wind tracer features, and determining their height using hyper-spectral sounding and imaging methods. Some of the hyperspectral observations from flights in December 2017 will be described, together with satellite and radiosonde observations similar in time and location. Critical laboratory test results will also be described.

Remote sensing radar instruments rely typically on active transmitters that have a power demand, which is difficult to cope with on CubeSats due to their size limitations. A passive reflectometer overcomes this problem by receiving the reflected beam from a known precise signal source in space. Due to the used frequency band, the signal modulation and the availability of their transmitter’s ephemerides, GNSS signals are perfectly usable for this purpose. The PRETTY (Passive REflecTometry and dosimeTrY) satellite is currently developed by TU Graz, RUAG Space and Seibersdorf Laboratories under a contract with ESA. PRETTY hosts two payloads: The first payload is a passive GNSS based reflectometer. The main scientific goal is the precise altimetric determination of ocean and sea-ice surfaces using the interferometric phase-delay altimetry approach. The interferometric approach avoids the local generation of the original signal by additionally receiving of the direct (not reflected) signal from the signal source, which subsequently is correlated with the reflected beam. This methodology will be applied for the first time in space. The second payload is a dosimeter for analysis of the space radiation environment in the PRETTY orbit by collecting data from different sensors. The dosimeter is capable of providing information on the total ionizing dose (TID) as well as on the linear energy transfer (LET) of the space radiation environment. The satellite mission has entered the detailed design phase and a launch is scheduled for early 2021, with a nominal operational lifetime of one year. In the present publication, we introduce the mission and observation concept, as well as the current status of the project.

The GLO instrument concept is a VNIR/MWIR solar occultation sensor designed to measure (all at < 1 km vertical resolution) O3, H2O, CH4, CO, HF, HCN, HCl, HDO, N2O, CO2 (for temperature), and aerosol from orbital altitudes. The vertical measurement range spans the entire middle atmosphere, but the sensor has been designed to particularly target transport and composition in the UTLS. With its small form factor and modest spacecraft requirements, GLO is well suited for constellation applications. We will describe one such implementation of GLO. The instrument concept, measurement and data acquisition approach, and potential applications will be discussed.

Target detection is one of the more popular applications of hyperspectral remote sensing. To enhance the detection rate, it is common to do preprocessing to reduce the effects of noise and other forms of undesired interference with the observed spectral signatures. In current earth observing systems, in particular small satellite systems, data rate limitations can make the utilization of sensors with high spectral dimensionality undesirable and even unobtainable. In this paper, the effect of different methods for dimensionality reduction and noise removal has been observed on multiple classical methods for signature matched target detection often used in hyperspectral imaging. The dimensionality reduction differs from resampling in the sense that the original spectral range and resolution can be restored via a linear transformation. This paper suggests that by combining dimensionality reduction and target detection, the resulting data cube has a reduced dimensionality and suppressed undesired effects. The ability to correctly detect spectral phenomena has improved while also achieving reduce data volume. Combining dimensionality reduction and target detection can also reduce the number of computational operations needed in later stages of processing, when operating on the projected space. The observed effects are demonstrated by using simulated and real-world hyperspectral scenes. The real-world scenes are from well-calibrated sensors e.g. AVIRIS, ROSIS, and Hyperion, of classified agricultural and urban areas. The simulated scene is generated using the ASTER library.

With the goal of landing crewed missions on the Moon and Mars in the next decade, mineral deposits on asteroids represent a potentially important resource for emerging space colonies. Deep-space missions can contemplate in-situ resource utilization, should suitable compounds be present. A necessary step for eventual resource exploitation is characterization of material abundances within candidate asteroids. Mineral maps could be generated by deploying CubeSat spacecraft to targeted asteroids, using Remote Laser Evaporative Molecular Absorption (R-LEMA) spectroscopy. In the R-LEMA scheme, a directed energy beam is used to probe molecular composition of a remote target. The laser-heated spot serves as a high-temperature blackbody source and ejected molecules create a plume of surface materials in front of the spot. Molecular composition is investigated by using a spectrometer to view the heated spot through the plume. Laboratory experiments allow comparison between predicted and measured profiles. Preliminary experiments described in this paper make use of solid-state samples so as to develop a library of spectra for comparison to future spectra obtained from samples in the gas phase.

We describe the design of the μBBR (micro Broad Band Receiver), a VLF receiver for the VPM mission. VPM is an AFRL CubeSat mission that will be launched into a 500 km circular orbit with a 45° inclination where it will continuously sample the VLF electromagnetic spectrum from 300 Hz to 30 kHz. These waves largely control the state of the radiation belts and improved understanding of them will lead to improved radiation belt predictive models. The µBBR consists of a single-axis electric dipole antenna, or dipole antenna assembly (DAA), a single-axis magnetic field search coil antenna, or search coil boom assembly (SCBA) and a payload electronics module (PEM). It is designed for high reliability by using radiation-tolerant components. The dipole antenna and search coil are aligned perpendicular to each other and the spacecraft is operated so as to keep both perpendicular to the background magnetic field as much as possible. All signal processing is implemented in an FPGA, using fixed-point arithmetic, without any volatile onboard firmware. Data is sampled at 80 kHz using a GPS-disciplined clock. Two date products are delivered: a reduced-bandwidth survey mode with 6.5, 13.1, or 26.2 second resolution, and a commandable full-resolution burst mode. Burst data can be taken in the time or frequency domain, can be selectively windowed along the time or frequency axes, and can be decimated by a factor of 2, 4, 8, or 16. Such capability is included because of anticipated data download rate limitations. The VPM spacecraft is scheduled for launch before the end of 2019.