This PDF file contains the front matter associated with SPIE Proceedings Volume 12729, including the Title Page, Copyright information, Table of Contents, and Conference Committee information.

Recently, ESA Member States have subscribed to funding Earth Observation activities on the scale of 2.7 billion Euros over the next 3 years. Corresponding workplans have been approved in early 2023 and numerous activities in the domain of Earth Observation satellites, ground segments, data management, science and applications are proceeding and are now open for participation.

This conference presentation was prepared for SPIE Remote Sensing, 2023

Two new systems are described to improve present capabilities for high-resolution atmospheric sensing from small satellite platforms. The NASA Time-Resolved Observations of Precipitation structure and storm Intensity with a Constellation of Smallsats (TROPICS) mission will significantly improve temporal resolution, and the NASA Configurable Reflectarray for Electronic Wideband Scanning Radiometry (CREWSR) instrument prototype will lead to significantly improved spatial resolution. TROPICS 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 60 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. The TROPICS constellation mission comprises four 3U CubeSats (5.4 kg each) in two 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. The four NASA TROPICS CubeSat constellation satellites were successfully launched into orbit on May 7 and May 25, 2023. The separate TROPICS Pathfinder mission launched on June 30, 2021, in advance of the TROPICS constellation mission, as a technology demonstration and risk reduction effort. CREWSR is a high-resolution, lightweight, low-power multiband (23, 31, and 50-58 GHz) radiometer with a deployable scanning reflectarray. It is envisioned to be fielded on an ESPA-class small satellite platform, whose stowed volume fits within 0.61m x 0.71m x 0.97m envelope. Once in orbit, the platform will deploy a large Reconfigurable Reflective Surface (RRS), as well as a multi-feed antenna connected to a multiband radiometer. These components allow for an electronically scanned beam for radiometric Earth observation. CREWSR would operate with a single, linear polarization, but fully polarimetric operation is also possible in principle. The reflectarray is also compatible with radar use, thus enabling wide-swath radar from a small satellite. This presentation will describe the on-orbit results over approximately two years for the successful TROPICS Pathfinder precursor mission and first light results from the TROPICS constellation mission and will overview the CREWSR design, prototype objectives, and recent laboratory measurement results.

The Active Cooling for Multispectral Earth Sensors (ACMES) is a 16U CubeSat technology demonstration mission funded by the NASA Earth Science Technology Office through the In-space Validation of Earth Science Technologies program. ACMES has two technology payloads for Earth IR imaging. The LWIR scientific instrument is the next generation Hyperspectral Thermal Imager (HyTI 2.0). HyTI-2.0 has 25 spectral bands between 8 μm to12.5 μm, and a ground sampling distance of 45 meters. The SWIR instrument is the Filter Incidence Narrow-band Infrared Spectrometer (FINIS) which is a compact and a lightweight instrument for measuring methane with a moderate spatial resolution (approximately 140 m) and wide field of view (approximately 10°). FINIS can both measure the methane concentration dispersed over large regions and detect point source emissions by observing individual plumes. Key to the ACMES mission is a miniature pumped fluid loop technology developed for CubeSats, the Active Thermal Architecture for removing the waste heat from this approximate 120W spacecraft. ACMES is planned to launch in late 2024 to an approximate 550 km SSO orbit with a one-year technology demonstration followed by an extended mission to collect scientific data with HyTI 2.0 and FINIS. ACMES is a joint development effort between Utah State University, Orion Space Solutions, and the Hawaii Space Flight Laboratory.

The HyTI (Hyperspectral Thermal Imager) mission, funded by NASA’s Earth Science Technology Office InVEST (In-Space 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 35 channels between 7.5-11 microns, at 13 wavenumber resolution, at a ground sample distance of approximately 60 m. Measured spectro-radiometric performance indicates narrow-band NEdTs of approximately 0.2K. 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.

Integrated active thermal control is a critical enabling technology for high-powered modern CubeSats and Small Satellites. We will discuss the design and development of the Active Thermal Architecture (ATA), a sub 1U integrated, active thermal control system based on a single-phase mechanically pumped fluid loop heat exchanger. The ATA leverages advanced Ultrasonic Additive Manufacturing (UAM) to directly incorporate the cooling channels into the spacecraft structure, creating multi-functional assemblies that help miniaturize and simplify the ATA system. The ATA also optimizes thermal rejection through a two-axis rotary fluid joint connected to an external deployable tracking radiator. The ATA is capable of bulk thermal rejection and zonal temperature control of payloads and CubeSat structures. The ATA will be featured on the upcoming Active Cooling for Multispectral Earth Sensors (ACMES) mission and will serve as payload support to the next-generation Hyperspectral Longwave IR (HyTI 2.0) instrument. HyTI is an advanced next-generation hyperspectral long-wave IR ground imager capable of producing LandSat equivalent science from a CubeSat platform. HyTI produces 25 spectral bands between 8 μm to12 μm with a ground sampling distance better than 45 meters. ACMES will also feature two student lead projects: The Filter Incidence Narrow-band Infrared Spectrometer (FINIS), a daytime Methane detector, and the Planar Langmuir Impedance Diagnostic (PLAID) instrument, a planar style RF impedance probe. ACMES is scheduled to launch to an approximate 550 km SSO orbit in late 2024. ACMES is funded by the NASA Earth Science Technology Office (ESTO) through an In-Space Validation (InVEST) grant.

This conference presentation was prepared for SPIE Remote Sensing, 2023

Imaging spectroscopy enables the observation and monitoring of surface properties thanks to the diagnostic capability of contiguous, spectral measurements from the Visible to the Shortwave Infra-Red portion of the electromagnetic spectrum. These observations of the Earth’s surface support the generation of a wide variety of new products and services, spanning across different domains relevant to various European Union (EU) policies that are currently not being met or can be substantially improved, not only for the public, but also for the private downstream sector. The Copernicus Hyperspectral Imaging Mission for the Environment (CHIME) aims to provide routine hyperspectral observations over the land and coastal zones through the Copernicus Programme in support of EU- and related policies for the management of natural resources, assets, and benefits. This unique Visible-to-shortwave Infra-Red spectroscopy based observational capability will in particular support new and enhanced services for food security, agriculture and raw materials. For the development of the Space Segment Contract (Phase B2/C/D/E1) Thales Alenia Space (France) as Satellite Prime and OHB (Germany) as Instrument Prime were selected. The contract was signed in November 2020 and the corresponding Kick-Off released the start of Phase B2. The System Requirement Review (SRR) was conducted in July 2021 and the Preliminary Design Review (PDR) is being conducted in 2022. Currently there are two satellites foreseen and each of the satellites will embark a HyperSpectral Instrument (HSI), a pushbroom-type grating Imaging Spectrometer with high Signal-to-Noise Ratio (SNR), high radiometric accuracy and data uniformity. HSI consists of a single telescope for three single-channel spectrometers covering each one-third of the total swath of approximately 130 km. The spectral range of each spectrometer is covering the entire spectral range from 400 to 2500 nm. CHIME data will be processed and disseminated through the Copernicus core Ground Segment allowing the generation of CHIME core products: L2A (bottom-of-atmosphere surface reflectance in cartographic geometry), L1C (top-of-atmosphere reflectance in cartographic geometry) and L1B (top-of-atmosphere radiance in sensor geometry). Additional higher level prototype products related to key vegetation, soil and raw material properties are also being developed. In this contribution, besides the mission requirements and planning, the main outcomes of the activities in Phase A/B1 and B2, as well as the planned activities for Phase C/D/E will be presented, covering the scientific support studies, the technical developments, and the user community preparatory activities.

The Land Surface Temperature Monitoring (LSTM), part of the expansion missions of the Copernicus programme, aims at providing data for land surface temperature and evapotranspiration at unprecedented spatio-temporal resolution, with the main objective of providing valuable data for improved water management at individual European field scale. This paper gives an overview of the instrument main requirements flowing down from the mission objectives, and the instrument design selected to fulfill them. The technical challenges are described as well as the key performances.

Quantum sensing has emerged as a promising approach for spaceborne Earth Observation (EO) with the potential to offer higher accuracy, sensitivity and stability than instruments used in EO missions so far. While several quantum sensors have been developed and successfully tested in ground-based experiments, with some of them even available as commercial devices, the identification of their potential applications in space remains a challenge. Nevertheless, there are some promising technologies, including cold-atom interferometers, Rydberg receivers, atomic vapor- and Nitrogen-Vacancy center-based magnetometers, and quantum lidar, that show potential for enhancing EO capabilities. In this presentation, we will discuss the latest developments and challenges in quantum sensing for EO at the European Space Agency (ESA), highlighting the most promising technologies and their potential applications. We will also discuss ongoing efforts at ESA to identify potential applications of these sensors and the roadmap for their deployment. Finally, we will conclude with a discussion of the future prospects for quantum sensing in EO and the wider space exploration domain.

The ALTIUS Mission (Atmospheric Limb Tracker for Investigation of the Upcoming Stratosphere) aims at the development of a limb sounder to monitor the distribution and evolution of stratospheric ozone at high vertical resolution in support of operational services and long-term trend monitoring. The ALTIUS Instrument novel concept consists of three hyperspectral channels using active tunable spectral filters to perform observations with a spectral resolution ranging between 1nm and 10nm. The spectral filters are using Acousto-Optic Tunable Filters (AOTFs) in the Visible (440-675nm) and NIR (600-1020nm) range, and a cascade of Fabry-Pérot Interferometers (FPI) in the UV (250-355nm) range. The ALTIUS Mission is currently in Phase C, with a Critical Design Review (CDR) planned in mid-2023 with Redwire Space N.V. as Mission Prime and OIP Sensor Systems N.V. as Instrument Prime. The paper presents the key technical challenges faced in the development of the ALTIUS Instrument up to its current CDR maturity level. Beyond a full system overview, detailed insight is provided of its optical concept, the choice and development challenges of its optical tunable spectral filters, the associated control electronics, the ALTIUS Instrument assembling (and alignment), its integration and testing strategy, the on-ground calibration plan and, finally, a summary of the achievable L0/L1 performances. A brief description of the ALTIUS Instrument in-flight calibration strategies will be presented too, along with a flavor of the stringent cleanliness and contamination control measures envisaged to ensure stable optical performances. Finally, the paper presents lessons learned from the subsystem qualifications activities and Instrument STM environmental test campaign, as well as an overview of the foreseen project milestones towards launch.

Currently, Japan Aerospace Exploration Agency (JAXA), Japan Meteorological Agency (JMA) and Japan Space Systems (JSS) are operating major Earth Observation Satellites. Ibuki (GOSAT) carrying TANSO-CAI and -FTS, GOSAT-2 carrying TANSO-CAI2 and -FTS2, Shizuku (GCOM-W) carrying AMSR2, Daichi-2 (ALOS-2) carrying PALSAR-2 , DPR on GPM-core satellite of NASA, and Shikisai (GCOM-C) carrying SGLI, are being operated by JAXA under cooperation with some domestic agencies, such as Ministry of Environment (MoE), National Institute of Information and Communications Technology (NICT). JMA is operating meteorological satellite Himawari-8 and -9 on geostationary orbit. Next generation of meteorological satellite is about to develop by JMA. JSS is operating ASTER on EOS-Terra satellite of NASA and HISUI on ISS. For coming satellites or instruments, JAXA is preparing CPR on EarthCARE satellite of ESA, ALOS-4 carrying PALSAR-3 and GOSAT-GW carrying TANSO-3 + AMSR-3 as follow-on mission for GOSAT-2. And the first Japanese Lidar mission MOLI on ISS is expected to entering development phase.

The Global Observing Satellite for Greenhouse gases and Water cycle (GOSAT-GW) is a polar-orbiting satellite carrying two mission instruments, the Total Anthropogenic and Natural emissions mapping SpectrOmeter-3 (TANSO-3) and Advanced Microwave Scanning Radiometer 3 (AMSR3). TANSO-3 is developed by the Ministry of the Environment as the follow-on mission of Greenhouse-gas Observation Satellite 2 (GOSAT-2) launched in 2018. AMSR3 is developed by the Japan Aerospace Exploration Agency (JAXA) as the Global Change Observation Mission-Water (GCOM-W) follow-on mission to keep continuity of the passive microwave observation. GCOM-W has been operated in almost 11 years in orbit, even after its nominal mission of five years in 2017. Continuous observation by the AMSR-series instruments and early launch of a follow-on instrument are now strongly desired both in science community and in operational fields. Specifications of the AMSR3 are almost equivalent to those of AMSR2. The characteristics and performances of existing 16 frequency channels are secured by making use of heritage design. Meanwhile, three high frequency channels (166 GHz, 183±3 GHz and 183±7 GHz) and 10-GHz channels with improved Noise Equivalent Delta Temperature (NEDT) are added for observation of solid precipitation and humidity and improvement in measurement accuracy of sea surface temperature, respectively. These additional channels will enhance data utilization in wide fields such as meteorology, water cycle studies, polar research, and fishery. Development of GOSAT-GW and AMSR3 had been officially approved in December 2019 and moved into Phase-C since March 2021. An overview and status of the mission are given in this paper.

Global carbon dioxide (CO₂) and methane (CH₄) flux distributions were derived by the inverse model analyses of CO₂ and CH₄ column-average concentration data from Greenhouse gases Observing SATellite (GOSAT) launched in 2009 and its successor (GOSAT-2) launched in 2018. GOSAT Level 4A CO₂ and CH₄ flux products are freely available from GOSAT Data Archive Service. Monthly net CO2 and CH₄ flux values are calculated for 42 land regions and 22 ocean regions for CO₂ and one ocean region for CH₄ using the inversion system with NIES TM atmospheric transport model. The preliminary version of GOSAT-2 Level 4A CO₂ product is being evaluated and will be released to the public in FY2023. GOSAT-2 Level 4A CH₄ product will be generated after the release of CO₂ product. GOSAT-2 Level 4A CO₂ product is generated using the inversion system named NICAM-based Inverse Simulation for Monitoring CO₂ (NISMON- CO₂) with about 2.5-degree grids and monthly time interval. The spatial distributions of small CO₂ sources and sinks will be shown by this product. GOSAT-GW, the third satellite in GOSAT Series to be launched in FY2024, will map CO₂ and CH₄ column concentrations with two spatial observation modes, Wide mode with 910 km swath and 10 km resolution, and Focus Mode with 90 km swath and 3 km or better resolution. Such image data will be used in the inversion analysis to obtain global and regional CO₂ and CH₄ net flux with higher spatial and temporal resolution than GOSAT and GOSAT-2.

The Advanced Land Observing Satellite-4 (ALOS-4) is the following mission of the Advanced Land Observing Satellite-2(ALOS-2). ALOS-4 carries two instruments, one is Phased Array-type L-band Synthetic Aperture Radar-3 (PALSAR-3) and the other is SPace based AIS for ships Experiment (SPAISE3). PALSAR-3 is the successor of PALSAR-2 aboard ALOS-2 and SPAISE3 is the successor of SPAISE2 aboard ALOS-2. Proto Flight Tests (PFT) for the ALOS-4 satellite system and the total end-to-end test including the ALOS-4 satellite system and ground segments were already completed. The operation preparations including operation training, calibration/validation preparation and coordination with users are on-going.

Monitoring of land vegetation is one of the prime objectives for Earth Observation satellite missions. Due to the penetration capabilities of low-frequency radar signals through vegetation canopies, L-band SAR is widely considered as a valuable tool for advanced vegetation monitoring. Based on the physical backscattering properties of the above-ground vegetation strata, polarimetric SAR (PolSAR) imaging can provide detailed information on crucial plant parameters such as amounts of biomass, growth heights, water contents, crop types, etc. 9 years in orbit, ALOS-2 has pioneered as a veritable long-term L-band SAR land observation mission. ALOS-2/PALSAR-2 has acquired unprecedented L-band time-series data with seamless coverage of the entire vegetated land area. Based on the achievements of its predecessor, we discuss the potential of ALOS-4/PALSAR-3 for further breakthroughs in both agriculture and forest monitoring from meter scale to continental scale. Particularly, the cutting-edge capability to observe 200-km swaths in high-resolution Stripmap (SM) mode, achieved by Digital Beam Forming (DBF), will allow overcoming the limitations of ALOS-2’s widely used 50-m resolution ScanSAR modes. Better spatial resolution and image quality paired with higher revisit frequency is expected to improve the reliability of numerous applications ranging from land cover classifications to biomass and yield estimations.

New concepts of compact Thermal Infrared (TIR) cameras were studied as the successor to the Compact Infrared Camera (CIRC) onboard the ALOS-2 satellite launched in 2014. The CIRC, mounting an uncooled bolometer array and weighing only 3 kg, has accomplished eight-year high-resolution (GSD~200 m) TIR earth observations, mainly monitoring active volcanos and wildfires. The next-generation compact camera should have similar size, weight, and power consumption (SWaP) performances to CIRC. Ground resolutions of 30 m to 50 m or below should be needed to understand temperature distributions for crop fields or to measure temperatures for narrow waters and fish farms in Japan. Uncooled bolometer cameras could not gain high MTF from earth-centered platforms to achieve that spatial resolution because of their sizeable thermal time constants. We are choosing cooled detector arrays that are sensitive in mid-wavelength infrared (MWIR, 3 μm to 5 μm). One of the technical advantages of MWIR wavelength is that optics will be much smaller than for longer wavelengths. We are studying the conceptual design of a compact camera that mounts the cooled Type-II Superlattice (T2SL) detector array, which JAXA has developed.

Regarding crop production, which is the basis for food security, improving yields, using fewer materials through the appropriate use of nitrogen fertilizers and pesticides, and protecting the environment have become important global issues. This is part of the Green Food System Strategy announced by Japan's Ministry of Agriculture, Forestry, and Fisheries (MAFF) in May 2021. In this context, we plan to launch a miniature satellite with a hyperspectral sensor to observe Canopy Nitrogen Content (CNC) and Solar-Induced Fluorescence (SIF) in the mid-to the late 2020s. A miniature hyper spectrometer with a wide spectral range of 400 nm to 1700 nm and a narrow spectral resolution of 2nm to 10 nm, with a relatively medium Ground Sampling Distance (GSD) of 70m and Signal-to-Noise Ratio (SNR) of approximately 130 is currently under consideration. System optimization, such as the trade-off between the GSD and SNR under mass and envelope constraints, and the introduction of cutting-edge technologies, such as visible-enhanced InGaAs detectors, are both critical to the realization of specific mission objectives. A feasibility study and preliminary payload design are presented in this thesis.

Nanosatellites are proliferating as low-cost dedicated sensing systems with lean development cycles. Kyushu Institute of Technology (Kyutech) and collaborators have launched a joint venture for a nanosatellite mission, Visible Extragalactic background RadiaTion Exploration by CubeSat (VERTECS). The primary mission is to elucidate the formation history of stars by observing the optical-wavelength cosmic background radiation. The VERTECS satellite will be equipped with a small-aperture telescope and a high-precision attitude control system to capture the astronomical data for analysis on the ground. However, nanosatellites are limited by their onboard memory resources and downlink speed capabilities. Additionally, due to a limited number of ground stations, the satellite mission will face issues meeting the required data budget for mission success. To alleviate this issue, we propose an on-orbit system pipeline to autonomously classify and then compress desirable image data for downlink prioritization and optimization. The system comprises a prototype Camera Controller Board (CCB) which carries a Raspberry Pi Compute Module four which is used for classification and compression. The system uses a lightweight Convolutional Neural Network (CNN) model to classify and determine the desirability of captured image data. The model is designed to be lean and robust to reduce the computational and memory load on the satellite. The model is trained and tested on a novel star field dataset consisting of data captured by the Sloan Digital Sky Survey (SDSS). The dataset is meant to simulate the expected data produced by the 6U satellite. The compression step implements GZip, RICE or HCOMPRESS compression, which are standards for astronomical data. Preliminary testing on the proposed CNN model results in a validation classification accuracy of 100% on the star field dataset, with compression ratios of 3.99, 5.16 and 5.43 for GZip, RICE and HCOMPRESS that were achieved on tested FITS image data.

In response to the recommendations from the 2017 U.S. National Academies decadal survey for Earth science, NASA initiated the Surface Biology and Geology (SBG) designated observable with five key research and applications focus areas: climate, ecosystems and natural resources, hydrology, solid Earth, and weather. SBG includes spaceborne measurements in the visible to shortwave infrared (0.4 micron to 2.5 micron) and in the mid- and thermal infrared (4 micron to 12 micron). High-level Thermal Infrared (TIR) data products include Earth surface temperature and emissivity, evapotranspiration, substrate composition, volcanic plumes, and high-temperature features. A team of scientists and engineers from the NASA Jet Propulsion Laboratory (NASA/JPL), Agenzia Spaziale Italiana (ASI), Istituto Nazionale Geofisica e Volcanologia (INGV), and the Istituto Nazionale Astrofisica (INAF) are now collaborating on an SBG-TIR joint project. In this concept, the JPL TIR instrument is an eight-band radiometer with a Ground Sampling Distance (GSD) of ⪅60 m at nadir and ⪅3-day revisit time. A two-band ASI Visible and Near Infrared (VNIR) camera with ⪅30 m GSD at nadir complements the TIR instrument. Both will be mounted on an ASI-provided spacecraft platform and launched into space on an ASI-provided launch vehicle. A multi-year international development effort will lead to a launch in the second half of this decade. To maximize the science and applications benefits the SBG-TIR team is also collaborating with personnel from the ESA Land Surface Temperature Monitoring mission (LSTM) as well individuals from the Thermal Infrared Imaging Satellite for High-resolution Natural resource Assessment (TRISHNA), a joint mission by CNES and ISRO.

Overview of the imaging spectrometer instrument for NASA’s Surface Biology and Geology mission. Following the 2017 release of the National Academies of Science, Engineering and Medicine’s Earth Science and Applications Decadal Survey (ESAS 2017), the National Aeronautics and Space Administration (NASA) announced the development of an Earth System Observatory (ESO), a series of missions designed to observe processes across the Earth’s interior, surface and atmosphere. One of the key identified investigation in the ESO series is the Surface Biology and Geology (SBG) mission. SBG will measure the composition and properties of Earth’s land, inland waters, and coastal oceans. The architecture of this mission consists of 2 satellites one covering the Visible Shortwave Infrared (VSWIR) and the Thermal Infrared (TIR) spectrum respectively and is slated for launch in the later part of the decade. This talk will focus on the new global coverage observation that will be made from space by the VSWIR Wide Swath (VSWIR-WS) imaging spectrometer instrument. This measurement is part of the Surface Biology and Geology (SBG) mission.

SMOS and SMAP radiometers have demonstrated the ability to monitor soil moisture and sea surface salinity and continue to provide high quality radiometric measurements to this day in extended mission operations. It is important to maintain data continuity for these science measurements. The proposed instrument concept (Global L-band active/passive Observatory for Water cycle Studies - GLOWS) will enable low-cost L-band data continuity (that includes both L-band radar and radiometer measurements). The objective of this project is to develop key instrument technology to enable L-band observations using an Earth Venture class satellite. Specifically, a new deployable reflectarray lens antenna is being developed that will enable a smaller EELV Secondary Payload Adapter (ESPA) Grande-class satellite mission to continue the L-band observations at SMAP and SMOS resolution and accuracy at substantially lower cost, size, and weight.

The Ocean Color Instrument (OCI) on NASA’s Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) mission is a hyperspectral Earth imager with a spatial resolution of 1 km x 1 km and a spectral resolution of 5 nm in 2.5 nm steps over 342 nm to 887 nm. In addition, OCI provides seven discrete bands in the 940 nm to 2260 nm Short-Wave InfraRed (SWIR) range. The front-end optical imager is a rotating mirror-based system that images the ground scene onto a slit with an instantaneous field of view of 16 km x 1 km. For the SWIR bands, the slit-image is re-imaged onto a 16x1 micro-lens array that effectively acts as the focal plane since each lens element is fiber coupled to wavelength filtered InGaAs and HgCdTe Photo Diodes (PDs). The pulse response of the detection system is critical to OCI SWIR performance. We find that PDs introduce an inherent slow tail in the pulse response due to slow diffusion moving carriers in their n and p regions. We show that this introduces response errors ranging from 1 down to 0.01 % for up to tens of science pixels after the pulse depending on the PD design and materials. It is shown that the response is distinctly different for the InGaAs and HgCdTe PDs. We explain how the front-end design can further increase this error. Finally, we detail the cause of the slow pulse response tail, how to model it, its impact on OCI performance and how it is characterized and corrected to meet OCI requirements.

Scheduled for launch in January 2024, the PACE mission represents NASA’s next investment in ocean biology, clouds, and aerosol data records. A key feature of PACE is the inclusion of an advanced satellite radiometer known as the Ocean Color Instrument (OCI), a global mapping radiometer that combines multispectral and hyperspectral remote sensing. A critical requirement for OCI is the high-contrast or spatial crosstalk specification (also referred to as in-field stray-light response). The requirement states that for global top-of-atmosphere radiances based on measured MODIS radiances, the global average residual contamination shall be less than 0.4% for 350 nm, 360 nm, 385 nm, 555 nm, 583 nm, 820 nm and 865 nm and less than 0.20% for all other multispectral bands. Accurate resolution of high contrast in TOA radiance images is important to estimate stray light contamination due to clouds, for studying small scale features like ocean fronts and for working in coastal and estuarine areas where the scales are 1km. This occurs in all wavelengths in the spatial direction. Knowledge of high contrast resolution makes up part of the artifact budget. Accurate measurement of the high-contrast performance of OCI requires laboratory Ground Support Equipment (GSE) that projects a scene of sufficient quality that the unwanted stray light of the GSE itself is not confused with the stray light response of the telescope. This paper concerns the development, analyses and test of the GSE to ensure the quality of the projected image is sufficient to verify the OCI requirements. Optical models were developed for both the instrument as well as the GSE and laboratory environment. Simulation of various non-ideal parameters were critical to accurately predict performance. Measurements using COTS cameras and lenses were also made of the projected GSE image to reasonably verify the optical model predictions. Measured and modelled results from OCI are discussed.

In this presentation, we will report our recent efforts in achieving high performance in Antimonides type-II superlattice (T2SL) based infrared photodetectors using the Barrier Infrared Detector (BIRD) architecture. The High Operating Temperature (HOT) BIRD Focal Plane Arrays (FPAs) offer the same high performance, uniformity, operability, manufacturability, and affordability advantages as InSb. However, Mid-Wavelength Infrared (MWIR) HOT-BIRD FPAs can operate at significantly higher temperatures (⪆150K) than InSb FPAs (typically 80K). Moreover, while InSb has a fixed cutoff wavelength (approximately 5.4 μm), the HOT-BIRD offers a continuous adjustable cutoff wavelength, ranging from approximately 4 μm to ⪆15 μm, and is therefore also suitable for long wavelength infrared (LWIR) as well. The LWIR detectors based on the BIRD architecture has also demonstrated significant operating temperature advantages over those based on traditional p-n junction designs. HyTI (Hyperspectral Thermal Imager) and c-FIRST (compact Fire Infrared Radiance Spectral Tracker) based on JPL’s T2SL BIRD FPAs. Based on III-V compound semiconductors, the BIRD FPAs offer a breakthrough solution for the realization of low cost (high yield), high-performance FPAs with excellent uniformity and pixel-to-pixel operability.

As part the phase A study for the GeoXO Lightning Mapper (LMX) Teledyne e2v has been contracted by NASA to develop and characterize an Engineering Demonstrator Unit (EDU). The full-size detector specification is under consolidation; however the format should be in the region of 1500 x 1500 pixels of about 24μm pitch. The key features and requirements are high Full Well Capacity (FWC) above 500ke- with a frame rate target above 500fps, 14 bits ADC resolution in Global Shutter mode is one of the modes considered for performance demonstration. This device must be highly sensitive at 770 nm with a QE above 80% while maintaining good MTF. This is achieved via a combination of thick silicon and reverse bias HiRho technology. The demonstrator consists of a representative reduced format of 600 x 500 of the full-size detector. This demonstrator unit has been designed, manufactured and fully characterized. In this presentation, the architecture approach to the full-size detector and the EDU will be presented along with the key silicon results from the Engineering Demonstrator Unit.

The Meteosat Third Generation (MTG) Programme is a EUMETSAT geostationary satellite mission developed by the European Space Agency (ESA). It will ensure the future continuity with, and enhancement of, operational meteorological (and climate) data from Geostationary Orbit as currently provided by the Meteosat Second Generation (MSG) system. The MTG satellites series is composed of 4 MTG-I and 2 MTG-S to bring to the meteorological community a continuous Imagery and Sounding capabilities with high spatial, spectral, and temporal resolution observations including geophysical parameters of the Earth based on state-of-the-art sensors. The first satellite (MTG-I1) was launched on 13th December 2022 by an Ariane 5 rocket. The commissioning of the whole system is expected to span over 2023. As part of the space segment of the mission, ESA and EUMETSAT performed the commissioning phase with the support of the Prime Contractor and the main unit's sub-contractors and suppliers. The recurrent satellites are being integrated and stored awaiting the availability of launchers, with a plan to launch MTG-S1 in Q1/2025 and MTG-I2 in Q1/2026. The main elements of the MTG-S1 satellite are now integrated and undergoing module level on-ground testing. This paper will address the overall mission and its instruments high level design features. It will introduce the MTG-I1 satellite performances as measured in-orbit and processed during the commissioning phase, before entering the routine operations and will discuss the future.

Future space missions of Earth Observation propose to use night-time remote sensing to target new observables that represent a long-standing observational gap or address urgent scientific and societal research questions. The key challenges to enable such missions are related to the capability of the payload to measure very low radiances and with an extremely large dynamic range, ranging from night-time radiances to day-time radiances. In this paper, we derive the flow-down for such missions: from the scientific objectives, we derive the measurement requirements, on which we perform trade-offs based on mission analysis and radiometric budget. Subsequently, we identify potential detectors for these missions, and we identify the gaps in current state-of-the-art technology.

The European Space Agency (ESA), in collaboration with the European Commission (EC) and EUMETSAT, is developing as part of the EC’s Copernicus programme, six new missions to strengthen the already existing family of six Sentinels missions. The six new Sentinel Expansion missions cover four themes: Safeguarding the Artic, Monitoring Land and Natural Resources, Food Security and Management and Combating Climate Change. For this last theme, a space-borne observing system for quantification of anthropogenic carbon dioxide (CO₂) emissions is in development. The anthropogenic CO₂ monitoring (CO2M) mission will be implemented as a constellation of identical Low Earth Orbit satellites, to be operated over a period of more than seven years. Each satellite will continuously measure CO₂ concentration in terms of column-averaged dry air mole fraction (denoted XCO2) along the satellite track on the sun-illuminated part of the orbit, with a swath width of 250 km. Observations will be provided at a spatial resolution of 4 km², with high precision (⪅0.7 ppm) and accuracy (bias ⪅0.5 ppm), which are required to resolve the small atmospheric gradients in XCO2 originating from anthropogenic activities. The demanding requirements necessitate a payload composed of three instruments, which simultaneously perform co-located measurements: a push-broom imaging spectrometer in the Near Infrared (NIR) and Short-Wave Infrared (SWIR) for retrieving XCO2 and in the Visible spectral range (VIS) for nitrogen dioxide (NO2), a Multi Angle Polarimeter (MAP) and a three-band Cloud Imager (CLIM). Following the Satellite PDR, the industrial activities have concentrated in consolidating the design of the three instruments and the platform as well as completing the different development models. The paper presents the status of these activities which are leading to the Critical Design Review before entering into the flight manufacturing and assembly phase.

In this contribution, the detector-characterization results and some of the on-ground calibration plans are presented for an adjusted and improved SPEXone satellite instrument. SPEXone is a highly compact multi-angle space spectro-polarimeter developed by a Dutch consortium for the NASA PACE observatory scheduled for launch early 2024. This instrument will enable detailed characterization of the microphysical properties of fine particulate matter or aerosols in the atmosphere from low Earth orbit, which is essential for climate, ecosystem, and human-health science. A successor to the SPEXone instrument is currently being developed, with a wider swath as the main change (250 km instead of 100 km), and with several design improvements to reduce straylight. The detector firmware was adjusted to enable the required higher frame rate, and to make the readout more robust. The detector was characterized in a similar way as for PACE, though even more extensively based on lessons learned. In particular, full illumination measurements were complemented with partial illumination measurements, where parts of the detector are covered using dedicated detector masks, to investigate peculiar signal-induced offset effects that were observed only late for PACE. Additionally, direct memory measurements were performed using time-dependent illumination generated using a fast electronic shutter. Following the detector characterization, instrument-calibration preparations have started. The instrument will be fully calibrated in ambient, complemented with a highly selective set of measurements in vacuum. The approach followed will be similar to PACE, but modifications will be made to deal with the increased swath. Important improvements will be implemented to improve the data quality, such as increased number of wavelengths for straylight measurements.

Remote sensing of aerosols requires spectropolarimetric information over different viewing angles with demanding polarimetric accuracy and growing interest for smaller designs. In this paper, we investigate an instrument design that implements a metasurface filter which enables both functions simultaneously, allowing further miniaturization and integrability. The instrument offers 1 km ground sampling distance over its entire field of view, in Low Earth Orbit, and the concept makes use of six modules to cover the wide field of view requested for aerosol retrieval with a total of seven radiation-resistant lenses. This choice enables an optical volume per module under 50mm × 50mm × 150mm and smaller relative angles of incidence. The filters are designed to cover six spectral bands from 443 nm to 870 nm with a spectral resolution of 2 nm to 5 nm. The wide spectral band is achieved by using three distributed Bragg reflectors with bandpass filters, integrated in one double-cavity structure that can be glued on a CCD/CMOS sensor. The two cavities, operating as a metasurface, contain scatterers of different dimensions enabling the fine-tuning of the spectral resonance and the polarization filtering. Multiscale forward modeling techniques are employed for the estimation of the polarimetric accuracy with optical aberrations and realistic coatings. Using radiance values from the PACE mission, polarimetric errors and SNR at each pixel are estimated and compared to requirements of state-of-the-art missions.

This work reports on the design, manufacturing and experimental validation of a highly compact waveguide bandpass filter intended for use in future earth observation applications. The low weight, small volume and reduced cost of the filter make it well suited for use with commercial cubesat platforms, enabling the deployment of THz EO instruments at scale and commercial exploitation of this largely untapped spectral region. Passive radiometry and spectroscopy from space-borne instruments are two of the mainstays of weather modelling, climate analysis and Earth Observation (EO). Passive instruments rely on the use of highly accurate bandpass filters to limit the observed spectrum to specific bands or frequencies of interest and to prevent saturation of the sensitive receiver electronics. Of these, the terahertz spectrum (100 GHz to 3 THz) is of great interest due to the unique interaction between THz radiation and various kinds of matter. However, commercial passive EO systems are currently limited to the microwave and visible/IR spectral regions due to the extreme cost, size, and complexity of developing THz EO payloads. As a result, THz EO is currently not deployed at large-scale, limiting its application to niche scientific and governmental contexts. This filter for radiometry at 183 GHz was developed and manufactured using TeraSi facilities, and it represents a first step towards the development of complete THz EO Microsystems-in-package (MSiP). The scalable technology platform being developed at TeraSi combines silicon micromachining, heterogeneous integration, and system-in-package techniques for the realization of highly accurate, compact and low-loss THz components and sub-systems. The design and manufacturing of the filter will be presented, as well as an analysis of the expected RF performance across a set of manufacturing tolerances.

The Φsat-2 mission from the European Space Agency (ESA) is part of Φsat mission lineup aimed to address innovative mission concepts making use of advanced onboard processing including Artificial Intelligence. Φsat-2 is based on a 6U CubeSat with a medium-high resolution VIS/NIR multispectral payload (eight bands plus NIR) combined with a hardware accelerated unit capable of running several AI applications throughout the mission lifetime. As images are acquired, and after the application of dTDI processing, the raw data is transferred through SpaceWire to a payload pre-processor where level L1B will be produced. At this stage radiometric and geometric processing are carried out in conjunction with georeferencing. Once the data is pre-processed, it is fed to the AI processor through the primary computer and made available to the onboard applications; orchestration is done via a dedicated version of the NanoSat MO Framework. The following applications are currently baselined and additional two will be selected via dedicated AI Challenge by Q3 2023: SAT2MAP for autonomous detection of streets during emergency scenarios; Cloud Detection application and service for data reduction; the Autonomous Vessel Awareness to detect and classify vessel types and the deep compression application (CAE) that has the goal of reducing the amount of acquired data to improve the mission effectiveness.

We propose an innovative miniaturized calibration stimulus, based on a hybrid tunable laser, combining a semiconductor optical source and a highly integrated photonics chip. This enabling technology allows the fabrication of calibration stimuli of extremely small size and high spectral resolution, in the Visible (VIS), Near Infrared (NIR) and Short-Wave Infrared (SWIR) ranges. We developed a calibrator breadboard, based on a tunable laser, with a central wavelength of 850 nm and a tunability range of approximately 50 nm. The breadboard integrates an electronics system, which drives the laser and provides the calibrator with electrical and data interfaces, and a back-end optical system, which shapes the calibrator output optical beam and defines its polarization. The breadboard passed performance and environmental testing. Results exhibit a linewidth of less than 0.1 pm, a tuning accuracy of less than 1 pm, an absolute wavelength drift of less than 1 pm/h, and continuous tunability over the full spectral range from 825 to 875 nm. Peak output power is higher than 2 mW. The obtained results are extremely promising and open a wide range of applications of the proposed system as on-board calibrator for both small and large optical instruments.

HYPSO-1 was launched in January 2022, equipped with a novel hyperspectral imaging payload with the main objective of performing marine research. In 2024, HYPSO-2, with an enhanced capture capacity, will be launched. The satellites can point their cameras off-nadir, a capability that is used to achieve a high temporal resolution over target areas. HYPSO-2 will have over ten times increased downlink capacity compared to HYPSO-1. Therefore, the ground system needs to be adjusted in order to accommodate more data. The main obstacles to overcome are tied to target areas being in geographically close vicinity of each other, estimating when captures are downlinked, and data handling onboard the satellites. In this article, we describe the systems that have been developed to handle the payload operations of the HYPSO-1 satellite and show the technical advances made in the development of the HYPSO-2 satellite. The elements needed for the automatic operation of the HYPSO-2 satellite are introduced and a system to integrate most of these elements is proposed. The system that is designed is deemed to be implementable and can become a fully automated planning and uplink pipeline, but operators would still be required to monitor the satellites’ health and perform troubleshooting.

The Institute of Optical Sensor Systems (OS) at the Robotics and Mechatronics Center of the German Aerospace Center (DLR) has more than 40 years of experience in high-resolution imaging and imaging technology. This paper presents the current status of the institute’s work on next-generation CMOS-TDI detector development. Together with the partners IHP (Leibniz Institute for High Performance Microelectronics), IMS (Fraunhofer Institute for Microelectronic Circuits and Systems), and JOP (Jena-Optronik GmbH), a new test detector was designed consisting of an embedded charge-coupled device (eCCD) and a readout integrated circuit (ROIC), combined as a silicon-bonded design. This approach enables operation at a line rate up to 150 kHz and a full well capacity above 150 ke-, thus making it very promising for high-spatial-resolution imaging systems. An FPGA-based engineering model environment with high design flexibility distributes all eCCD clocking and ROIC control signals. The unidirectional eCCD design is optimized for electrical charge injection tests and is used to verify in-orbit initialization approaches, including eCCD signal reconstruction. The paper will outline this procedure. Due to the accessible detector building blocks, this setup is ideally suited for future evaluation and verification of accumulative radiation effects on the eCCD and ROIC structures and determining possible corrective actions to contain overall radiation-related performance degradation over the mission lifetime. The evaluated method is intended to estimate the sensor’s behavior under space environmental conditions during the entire mission by introducing a detector initialization phase.

This high-resolution satellite is equipped with a push-broom high-resolution camera (PMS) that consists of panchromatic, blue, green, red, and near-infrared bands. The Moon is considered an stable light source, unaffected by atmospheric conditions, making it an ideal reference for absolute and relative radiation calibration of remote sensors. To utilize the Moon for calibration purposes, the satellite implemented two specific imaging modes: lunar push broom for absolute radiation calibration and lunar side-slither for relative radiation calibration. The lunar observations conducted by this satellite in orbit were highly successful. In 2019, the satellite conducted lunar observations at various lunar phase angles, while in 2021 and 2022, observations were specifically conducted during the full moon. These observations yielded many effective full lunar disk images. The stability of the PMS camera was analyzed using the band ratio irradiance method. Analysis of the satellite's four-year lunar observation data revealed a strong correlation between the lunar irradiance measured by PMS and the lunar phase angle. The analysis of the band ratio indicated that the multi-spectral bands are stable. However, the PAN band exhibited a tendency to attenuate, with a decay rate of approximately 0.0086 per year.

Cataloguing and recognition of space targets is becoming one of the important research contents of Space Situational Awareness (SSA). As is known that spectral feature is one important method for spatial targets classification and recognition. Based on the facts that objects have unique spectral distributions, characteristic spectra of objects can be used to classify and recognize objects. In order to acquire data cube of targets in both spatial and spectral dimensions by a snapshot, a hyper-spectral computing imaging technology with double channels was proposed in this paper. The imager can quickly acquire and reconstruct spectral data of space targets and then confirm the type of targets by comparing with prior spectral databases of different space targets. Sensitivity of the imager affects the longest detection distance and the spectral resolution of targets. In order to enhance its sensitivity, SPAD array with detection sensitivity to single-photon level can greatly enhance systems' performances.

The third VIIRS instrument, launched onboard the JPSS-2 satellite (also referred to as the NOAA-21) on November 10, 2022, is currently operated in a fleet that includes the S-NPP and NOAA-20 satellites that were launched on October 28, 2011, and November 18, 2017, respectively. In this paper, we provide an overview of NOAA-21 VIIRS initial on-orbit operation and calibration activities and a comprehensive assessment of its early on-orbit performance, including analyses made during its initial post-launch testing phase as well as under current nominal operations. The instrument performance examples presented in this paper include but are not limited to its detector signal-to-noise ratios for the reflective solar bands, the noise equivalent temperature difference for the thermal emissive bands, on-orbit changes of its spectral band responses, and the performance of its on-board calibrators, such as solar diffuser on-orbit degradation and blackbody temperature stability and uniformity. Also discussed in this paper are comparisons of NOAA-21 VIIRS on-orbit performance with its predecessors on-board the S-NPP and NOAA-20 satellites over the same operating period, as well as potential improvements for NOAA-21 VIIRS as its mission continues.

The Moderate Resolution Imaging Spectroradiometer (MODIS) on board the Terra and Aqua spacecrafts were launched in 1999 and 2002, respectively. To maintain climate quality data, each instrument performs calibration operations on-orbit using both on-board calibrators and observations of external targets, such as the Moon. For calibration consistency, the Moon is viewed during regularly scheduled spacecraft roll maneuvers in order to keep the lunar phase angle within a specified range. Changes in the view geometry are accounted for by the USGS ROLO model. However, starting in 2022, orbital maintenance maneuvers for both instruments are no longer being performed. Each instrument orbit has begun to drift to a higher beta angle, which changes the achievable phase angle range of the lunar observations. In this work, we investigate the impact of the orbital drift on the MODIS lunar calibration. We predict that the optimal phase angle range will change by approximately 20° (towards a full Moon) by the end of 2026. While differences in the view geometry can be accounted for using ROLO, phase angle residuals are seen in the model corrected results which can cause bias in the trending as the orbit drifts. Using the unscheduled Moon data, we develop a correction to these phase residuals in both instruments which shows that we expect drifts in the trends up to 1% for most bands by 2026 if left uncorrected.

The VIIRS Day/Night Band (DNB) is a panchromatic band ranging in wavelength from 500-900 nm. The DNB uses three gain stages to span over seven orders of magnitude of dynamic range and can observe scenes as dim as city lights at night up to sunlight reflected off clouds during the day. While the space-view port is typically used to measure the background signal for most VIIRS bands, for the DNB, it has been shown that the High-Gain Stage (HGS) is able to observe bright stars down to magnitude +7 with good sensitivity. The star observations have been used to assess the gain trending, spectral response, and for intercomparison of the DNB between sensors on different platforms (such as SNPP and NOAA-20 VIIRS). In this work, we extend our previous methodology to perform calibration assessments of the DNB Mid-Gain Stage (MGS). For the MGS, stars brighter than approximately magnitude +3 generate sufficient signal for our assessments. In addition to gain stability and instrument intercomparisons, these observations can also be compared to the HGS star observations on the same platform. This allows us to derive the MGS/HGS gain ratio independently from the solar diffuser observations.

Scheduled to launch in 2024, the Ocean Color Instrument (OCI) onboard the Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) mission will collect hyperspectral data from 315 nm to 895 nm via two grating spectrometers (in both the blue and red spectral regions) and 9 multi-spectral bands in the short-wave infrared (940 nm to 2260 nm). The increased spectral resolution and radiometric accuracy is expected to improve upon data collected by heritage sensors such as SeaWiFs, MODIS, and VIIRS, allowing new applications in ocean color, aerosol, and cloud science. During ground testing, higher than expected spatial-spectral crosstalk was measured for the hyperspectral bands in the blue spectrograph. Using a monochromatic-collimated light source, light from a single science pixel (1km x 1km) was found to produce crosstalk signals over 31 pixels in the cross-track direction. This spatial augmentation is caused by the spectral crosstalk’s asynchronous spatial movement during Time Delay Integration (TDI). To fully characterized the magnitude and spectral dependency from this, a crosstalk model was developed by synthesizing data collected from monochromatic-collimated light and monochromatic light that filled the OCI optical aperture. The model was validated by showing good agreement between predicted values and other relevant test data collected using both monochromatic and white light sources.

The ALTIUS (Atmospheric Limb Tracker for the Investigation of the Upcoming Stratosphere) Earth observation mission is an atmospheric limb sounder with three independent hyperspectral imagers. A spectrally tunable Fabry-P´erot Interferometer cascade in the ultraviolet (250 nm to 355 nm), and two Acousto-optic tunable filters covering the visible (440 nm to 675 nm) and near-infrared (600 nm to 1020 nm) respectively perform measurements to obtain atmospheric ozone data. This paper addresses the ALTIUS Instrument numerical model developed in MATLAB by the European Space Agency to confirm the compliance status regarding the Instrument Level zero requirements, perform sensitivity analyses, assist in design trade-off exercises, and monitor the industrial instrument development progress. The model employs a modular approach, whereby the optical assembly is separated into individual functions representing the optical units within the instrument channels, including the modeling of less conventional spectral tunable filters adopted within the ALTIUS Mission. The model is designed to be versatile to follow the hardware driven input along with the project life cycle. Finally, this paper provides examples of how this model has contributed to instrument design decision confirmation, presents a selection of current Level zero performance results of the ALTIUS instrument channels (signal-to-noise ratio, spectral response function, full width half maximum, etc.).

The increasing intensity and frequency of wildfires necessitate novel approaches in understanding and monitoring vegetation fuel flammability. Here we introduce OzFuel, a multi-year project that aims to develop a constellation of hyperspectral Earth Observation (EO) instruments to monitor vegetation fuel flammability at the global scale. To achieve this, the roadmap initiates with the launch of a technology demonstrator by 2026, equipped with four distinct passbands in the Short-Wave Infrared (SWIR) range of the electromagnetic spectrum, and coverage over regional Australia will capture flammability data at monthly intervals approximately. This specific instrument is currently being designed and prototyped. By 2028, a refined iteration of the OzFuel, featuring enhanced spectral resolution (15 to 25 spectral bands), will offer improved differentiation among vegetation fuels with varying levels of flammability. This advancement will stem from its heightened sensitivity to a broader array of traits that contribute to flammability. Moreover, a comprehensive coverage across Australia and focused acquisitions over the Americas and Europe will be achieved. In 2030 a global-scale monitoring system that offers weekly global updates on vegetation fuel flammability is planned. Unlike other satellite missions, OzFuel aims to monitor vegetation fuel flammability to inform where fires are likely to occur before ignition occurs enabling proactive management strategies to reduce the impact of wildfires and improve natural disaster preparedness and resilience.

With recent advances in large-scale space telescope missions, new sensors and technologies are made available for use in space for the first time. With the recent developments for the Coronagraph Instrument (CGI) instrument of the Nancy Grace Roman Space Telescope (NGRST), Electron Multiplying CCD (EMCCD) readout electronics and sensors are being qualified for extended use in space. To make this new remote sensing technology available for a wider range of missions, a new space camera version has been developed, with the first units outfitted with the Teledyne-e2v CCD201-20 EMCCD sensor. This novel camera, equipped with proprietary Camera Proximity Electronics (CPE), is built with a balance of space-qualified components and commercial off the shelf components with flight heritage to optimize cost, performance, and reliability. In addition to direct imaging and characterization of exoplanets, the sensitivity of this camera is also enabling Space Situational Awareness applications. The first imaging, random vibration and TVAC testing results of this new 1U camera platform named nüSpace will be presented.

The evolution of UAV and the great development of micro-satellites pose a number of challenging problems all related to minimize the needed resource on board and to maximize the amount of information obtained from the remote and close sensing activities. What usually happens is to have quite specialized sensors onboard depending on the most required characteristic of the images, high spatial resolution, high spectral resolution, high radiometric accuracy, etc. The authors developed an advanced approach able of minimizing the resources on board while maximizing the amount of information obtained out of them applying AI base post-processing. The on-board equipment and the corresponding ground post-processing provide Spectral and Colorimetric Imaging with notable spectral resolution, accuracy and precision starting from only two acquired images. The result is a Spectral and Colorimetric Imaging System with 13 bands per pixel with precision in the order of 98%, and CIELAB colorimetric coordinates per pixel with a precision of dE2000 ⪅2, starting from only two RAW images.

The aim of this paper is to present the specifications of the EarthDaily Constellation, a scientific-grade EO mission, and the first results produced using a simulated dataset covering the September 2018 to August 2020 period over the Toulouse area in South of France. Two launches are scheduled in 2024 to put into orbit the ten satellites of the constellation. With an expected lifespan of over ten years, the constellation will collect daily imagery of the planet using a unique combination of 22 spectral bands in the VNIR, SWIR and TIR, many of which will be up to 5m GSD. The EarthDaily Constellation is a systematic acquisition mission, i.e., always-on over land, always nadir looking, with targeted geometric and radiometric quality aligned with Sentinel-2. In our paper, we will provide first details on the space segment main characteristics and bands specifications. We will also present the creation process of a simulated dataset based on actual Venµs, Landsat, MODIS and Sentinel-2 observations, that provides a realistic simulation of a higher revisit time. Eventually we will address an example of perspective on agricultural applications, especially focusing on the first scientific results we obtained on evaporative fraction estimation from thermal infrared, and irrigation events detection. Those first results demonstrate the added value that will be brought by ED constellation.

The NOAA-21 VIIRS instrument has successfully operated since its launch on November 10, 2022. A panchromatic channel onboard VIIRS, referred to as the Day-Night Band (DNB), was designed with multiple gain stages resulting in a large dynamic range and high sensitivity such that its detectors can make observations during both spacecraft day and spacecraft night. An onboard Solar Diffuser (SD) panel provides a well-understood calibration source for the Low Gain Stage (LGS). While there is no direct, onboard calibration source for the Mid Gain Stage (MGS) or High Gain Stages (HGS), measurements of the SD during times of indirect solar illumination can provide relative gain ratios between the LGS/MGS and MGS/HGS. Results from an early mission pitch maneuver and regular new moon observations are used in combination with onboard calibrator trends to determine the DNB dark offset (DN0) levels. In this paper, we present details for the NOAA-21 VIIRS DNB on-orbit calibration and highlight its early mission performance. Calibration coefficients look up tables (LUTs) are calculated by the NASA VIIRS characterization support team (VCST) for the latest NASA Level 1B (L1B) Collection 1 products. DNB straylight contamination has been observed to differing degrees for earlier VIIRS instruments currently on both the SNPP and NOAA-20 spacecraft. We discuss the impact of straylight on the NOAA-21 VIIRS DNB in comparison to the previous instruments and the performance of our current straylight correction for L1B radiance products.

Spectral imaging is a method to acquire the spectrum of the light for each point in the image of a scene. By combining classical imaging with Fourier-transform spectrometry it is possible to acquire hyperspectral images with higher spectral accuracy and lower times compared to standard dispersive optical systems. The technique is based on interferometry and is hence technically challenging as it requires to generate field replicas with delay controlled within a small fraction (1/100 or better) of the optical cycle. Standard FT spectrometers are heavy, cumbersome and too sensitive to mechanical and thermal perturbations for use in portable devices or for deployment in space applications. Here we propose and experimentally validate a compact FT-based hyperspectral camera, in which the FT module is an innovative ultra-stable birefringent common-path interferometer (the Translating-Wedge-Based Identical Pulses eNcoding System, TWINS). TWINS has intrinsic interferometric stability, it is lightweight and is ultracompact, making our FT-based hyperspectral camera an ideal device for portable on-field and spaceborne applications. Our prototype camera is able to measure absolute reflectance and fluorescence with very high spectral accuracy in the visible and near-infrared spectral range and can be extended to the spectroscopically rich thermal infrared range (3 mu;m to 14 μm) using suitable birefringent materials and detectors. We present some examples of application in the visible and TIR ranges.

The Visible Infrared Imaging Radiometer Suite (VIIRS) instrument is currently operating onboard the NOAA-21 (or JPSS-2) satellite, which was launched successfully from the Vandenberg Space Force Base in California on November 10, 2022. This is the third VIIRS instrument flying on a series of Joint Polar Satellite System (JPSS) satellites, including S-NPP and NOAA-20 (or JPSS-1), along with other Earth observing instruments on board. The measurements collected by VIIRS are used for weather forecasting and environmental science research. Among 22 spectral bands of VIIRS, there are seven mid- and long-wave infrared Thermal Emissive Bands (TEB) ranging from 3.7 to 12.2 microns at two different spatial resolutions; imagery resolution bands (I-bands) I4 and I5 are 375 m per pixel at nadir, and moderate resolution bands (M-bands) M12 - M16 are 750 m. The VIIRS TEB detectors are calibrated by an On-Board Calibrator (OBC) blackbody (BB) at controlled temperatures with a deep Space View (SV) for background signal measurement. Prior to launch, the TEB went through rigorous pre-launch calibration and characterization tests in ambient and thermal vacuum environments. During the initial post-launch testing (PLT) period, a comprehensive set of tests and spacecraft maneuvers were performed to ensure the health of the satellite and all sensors. The PLT results help the understanding of instrument response and performance, and to bridge the calibrations between pre-launch and post-launch for traceability. This paper provides an overview of NOAA-21 VIIRS TEB PLTs with their results and follow-on on-orbit performance. Comparisons with NOAA-20 and S-NPP VIIRS TEB are also made in various categories including noise characterization, blackbody stability, and detectors response.

In recent years, small satellites have been utilized for remote sensing from Low Earth Orbit (LEO) with a spatial resolution of several meters. However, improving the temporal resolution for LEO remote sensing is challenging because of the short orbital period. Observation techniques using remote sensing from a Geostationary Orbit (GEO), or its nearby orbit are becoming increasingly crucial, particularly in disaster monitoring, due to their ability to provide high-temporal resolution. To improve both temporal and spatial resolutions from GEO, it is necessary to use an optical system with a diameter of several meters due to the diffraction limit. We propose the Formation Flying Synthetic Aperture Telescope (FFSAT). One of the key issues is realizing the optical system with an accuracy of less than 1/10 of the observation wavelength to get synthesized images. We propose a method for estimating and correcting misalignment and optical aberrations using adaptive optics.

Coded aperture imaging spectrometer is a new type of hyperspectral imaging instrument. The space-borne hyperspectral imager makes images by pushing and sweeping. In the ideal imaging model, it is assumed that one pixel is separated between two adjacent frames so that the target information can be accurately reconstructed. When coding aperture imaging is performed under motion compensation, the moving distance of the object image on the focal plane at each imaging time is different, and there is an amount of dislocation, resulting in decoding error of the decoded and restored data along the direction of the orbit, and the phenomenon of ground object "double shadow" and spectral decoding distortion appear in the simulation image. The amount of misalignment under different compensation modes is different, resulting in different decoding errors. The mathematical model of target data encoding and decoding in push-sweep coded aperture imaging and the mathematical model of field of view optical axis angular velocity in motion compensation mode were constructed. The simulation method of coded aperture imaging hyperspectral data under motion compensation was established, and the simulation data quality was analyzed. Through data quality analysis, it can be seen that under the uniform angular velocity mode, the uniform ground velocity mode and the uniform integral time mode, the cumulative amount of dislocation decreases successively, which is 5.7 m, 0.7 m and 0 m, respectively. The "double shadow" phenomenon of the simulated image becomes less and less obvious, and the image quality becomes clearer and clearer. Meanwhile, the restoration and reconstruction accuracy of the coding aperture imaging improves successively.