Through an innovative public-private partnership, a new generation of high-fidelity imaging spectrometers has been designed for the detection and measurement of methane (CH4) and carbon dioxide (CO2) plumes from super-emitters to help improve accounting and enable reduction of greenhouse gases in the Earth’s atmosphere. Two identical instruments, built concurrently at NASA Jet Propulsion Laboratory (referred to by JPL as the Carbon Plume Mapper project “CPM”) and Planet Labs as part of the Carbon Mapper Coalition, will measure the spectral range of 400 – 2500 nm with a spectral sampling of 5.0 nm. The identical optical design comprises a three-mirror anastigmat (TMA) telescope and Dyson form spectrometer which reduces volume and mass for a fast (F/1.8) optical system. The instruments will be integrated into Planet-built Tanager satellites and launched into low-Earth orbit (LEO). This work describes the assembly and alignment of the two identical instruments. At the subsystem level, both instruments follow the same procedure. For telescope alignment, the mirrors are first coarsely aligned with a coordinate measuring machine (CMM) and then finely aligned in a double-pass interferometer setup. The spectrometer subsystem is aligned onaxis using a commercial lens alignment instrument for precise, non-contact measurements. The telescope and spectrometer alignment results and performance are presented and compared. At the system level, the procedures deviate due to the separate and unique optical ground support equipment (OGSE) configurations utilized by JPL and Planet to implement the same instrument design. Both end-to-end optical alignment configurations are discussed, and the final CPM performance is shown with a focus on the five key and driving imaging spectrometer performance requirements.
Through an innovative public-private partnership, a new generation of high-fidelity hyperspectral imaging spectrometers has been designed to pinpoint, quantify, and track methane (CH4) and carbon dioxide (CO2) point-source emissions from super-emitters to help enable reduction of greenhouse gases in the Earth’s atmosphere. Two identical instruments, built concurrently at NASA Jet Propulsion Laboratory (referred to by JPL as the Carbon Plume Mapper project, CPM) and Planet Labs as part of the Carbon Mapper Coalition, feature an identical design which comprises a glass-ceramic, three-mirror anastigmat (TMA) telescope, held in place via a composite metering structure, and Dyson form spectrometer which reduces volume and mass for a fast (F/1.8) optical system. The telescope has a focal length and cross-track field of view (FOV) of 400 mm and 2.6 deg, respectively. Operating in the 400 – 2500 nm spectral range with 5.0 nm sampling, this spectrometer design has the sensitivity and resolution required to meet the demanding needs of space-based detection and quantification of CO2 and CH4 emissions. This work describes the instruments’ optomechanical configuration.
The Ultra-Compact Imaging Spectrometer Moon (UCIS-Moon) instrument is a pushbroom shortwave infrared (SWIR) imaging spectrometer prototype developed at NASA’s Jet Propulsion Laboratory (JPL), California Institute of Technology under the Development and Advancement of Lunar Instrumentation (DALI) program. It is designed for integration with a lander or rover for lunar surface science missions. Operating over a 0.6 to 3.6 micron spectral range with 10 nm sampling and a 36 degree field of view, UCIS-Moon is capable of detecting spectral absorptions from common lunar materials, OH species, molecular H2O, water ice, organics, and placing mineral identifications within an established geologic context at the cm to m scale. We discuss instrument assembly, alignment, and measured laboratory optical performance, which meets or exceeds the high-uniformity and high-resolution requirements while achieving a wide spectral range, field of view, and environmental tolerance, with limited mass and power resources. As such, the UCIS-Moon imaging spectrometer is well-suited to address key science questions about lunar geology, the abundance, sources, and sinks of volatiles at the Moon, and the distribution of possible in situ resources for future human exploration.
KEYWORDS: Equipment, Gas cells, Dark current, Fabry–Perot interferometers, Signal to noise ratio, Black bodies, Vacuum chambers, Thermography, Infrared radiation
Hyperspectral infrared sounders measure the profiles of temperature and water vapor in the atmosphere and the concentration of trace gas species. Instruments such as NASA Atmospheric Infrared Sounder (AIRS) on the Aqua spacecraft have proven their value for weather and climate research, atmospheric composition research, and high impact to the operational forecast at NWP centers worldwide. Reducing the size, weight and power of these instruments is key to enabling more rapid revisit when deployed in Low Earth Orbit (LEO), enabling new measurements such as 3D Atmospheric Motion Vector (AMV) winds, and reducing the cost of these instrument for future deployment in LEO, Geostationary Earth Orbit (GEO) and aircraft platforms. NASA and NOAA have sponsored technology maturation at JPL of the CubeSat Infrared Atmospheric Sounder (CIRAS) to demonstrate the use of wide field grating spectrometer optics and large format FPA technologies included in CIRAS for infrared sounding. These include a 2D format High Operating Temperature-Barrier Infrared Detector (HOT-BIRD), a silicon Immersion Grating, and Black Silicon for the CIRAS entrance slit and blackbody. Thermal Vacuum (TVac) performance testing of CIRAS has been completed achieving TRL 5 for a full scale brassboard of the instrument. Testing included spatial, spectral, and radiometric response of the instrument including measurements of the transmission in a gas cell. Results show excellent performance from the system with the exception of a high background flux from the Integrated Dewar Cryocooler Assembly (IDCA). The IDCA is not planned for flight use and projections of the performance in the flight configuration are discussed. Through this testing the instrument has reached TRL 5. Recently, the NASA Earth Science Technology Office (ESTO) awarded JPL a contract to fly the CIRAS in an aircraft, called the Pyro-atmosphere Infrared Sounder (PIRS), to measure the convective environment around wildfires.
The High-resolution Volatiles and Minerals Moon Mapper (HVM3) is a pushbroom shortwave infrared (SWIR) imaging spectrometer developed at NASA’s Jet Propulsion Laboratory (JPL), California Institute of Technology, for the Lunar Trailblazer mission. The mission, a part of NASA’s Small Innovative Missions for Planetary Exploration (SIMPLEx) program, pairs HVM3 with University of Oxford’s Lunar Thermal Mapper (LTM) to determine the form, abundance, and distribution of water on the Moon, while providing a potential reconnaissance opportunity for future landed missions. The HVM3 optical design utilizes heritage from NASA’s Moon Mineralogy Mapper (M3), and maintains a compact form while extending to longer wavelengths. Operating at F/3.4 with a spatial resolution of 70 meters per pixel and a spectral resolution of 10 nm over the 0.6 to 3.6 microns spectral range, HVM3 is optimized for the detection of volatiles to map OH, bound H2O, and water ice at the Moon, including the Moon’s permanently shadowed regions (PSRs). We discuss the optical specifications, optical design, alignment, and initial measured laboratory performance of the HVM3 instrument.
The Visible Mid-wave Dyson Imaging Spectrometer (VMDIS) is a JPL-developed prototype instrument whose main goal is to address three key technical challenges for the next generation of imaging spectrometers for solar system exploration: (1) High signal-to-noise ratio (SNR) measurements for mapping of minerals and volatiles on solar system targets including comets, asteroids, rocky moons, icy moons, and planets especially Mars; (2) Miniaturization for low-cost mission platforms (reducing the size, mass, and power requirements compared to current options); and (3) excellent spectral cross-track and spectral-spatial uniformity required by todays advanced algorithms for rigorous quantitation with uncertainties. The core of VMDIS is the imaging spectrometer instrument: an optically fast F/1.8 Dyson imaging spectrometer covering a spectral range from 600 nm to 3600 nm, with a spectral sampling of 7 nm. Different telescopes can be used with different implementations of VMDIS to tailor the IFOV and FOV of the instrument. With its prototype telescope, the instrument enables a field of view (FOV) of 28°, with an instantaneous FOV of 0.5 milliradians subtended by each 18 μm cross-track pixel. The size of the VMDIS prototype including the telescope and heritage electronics is roughly equal to 3U (3 units – 1 unit measuring approximately 10×10×10 cm), with a mass < 8 kg and payload power < 40 W. With next generation electronics in development this mass falls below 3 kg. We present an overview of the optical, mechanical, and thermal design of VMDIS, which is required to fabricate this instrument within very demanding resource allocations. The design of the signal chain electronics is also detailed. In addition, preliminary alignment, characterization, and calibration measurements, obtained with the instrument operating in relevant space-type environment, are also discussed. While tested with an available 30-μm detector array, VMDIS is designed for a 18-μm digital readout detector array. VMDIS is intended to pave the way for future low-cost, small form factor imaging spectrometers with state-of-the-art performance in terms of combination of spectral range, high throughput, exceptional uniformity, as well as configuration flexibility for both orbital and landed mission, for the next decade and beyond.
We report on the design performance of a compact imaging spectrometer suitable for planetary missions with U-Class spacecraft. It is a fast (F/1.9) and wide field instrument covering the range 600-3600 nm with 10 nm sampling and a 1000 pixel by 18 μm wide slit. The spectrometer is designed for use with a digital readout focal plane array that further aids miniaturization.
The Snow and Water Imaging Spectrometer (SWIS) is a science-grade imaging spectrometer designed for CubeSat integration, spanning a 350- to 1700-nm spectral range with 5.7-nm sampling, a 10-degree field-of-view, and 0.3-mrad spatial resolution. The system operates at F / 1.8, providing the high throughput for low-reflectivity (<1 % ) water surfaces, while avoiding saturation over bright snow or clouds. The SWIS design utilizes heritage from previously demonstrated instruments on airborne platforms while advancing the state of the art in compact sensors of this kind in terms of size and spectral coverage. Compared with airborne campaigns, the CubeSat platform allows for more frequent and regular sampling, while maintaining intermediate to high resolution relative to heritage global sensors. Through frequent repeat observations from space at a moderate spatial resolution, SWIS can address key science questions concerning aquatic and terrestrial ecosystem changes, cryosphere warming and melt behavior, cloud and atmospheric science, and potential impacts of climate change and human activities on the environment.
The Snow and Water Imaging Spectrometer (SWIS) is a science-grade imaging spectrometer and telescope system suitable for CubeSat applications, spanning a 350-1700 nm spectral range with 5.7 nm sampling, a 10 degree field of view and 0.3 mrad spatial resolution. The system operates at F/1.8, providing high throughput for low-reflectivity water surfaces, while avoiding saturation over bright snow or clouds. The SWIS design utilizes heritage from previously demonstrated instruments on airborne platforms, while advancing the state of the art in compact sensors of this kind in terms of size and spectral coverage. We provide an overview of the preliminary spacecraft configuration design for accommodation in a 6U CubeSat platform.
Mapping and quantifying lunar water ice addresses one of NASA’s Strategic Knowledge Gaps to understand the lunar resource potential for future human exploration of the Moon. Lunar Flashlight is an innovative NASA CubeSat mission dedicated to mapping water ice in the permanently-shadowed and occasionally-sunlit regions in the vicinity of the lunar South Pole. Lunar Flashlight will acquire these measurements from lunar orbit using a multi-band laser reflectometer composed of an optical receiver aligned with four lasers emitting different wavelengths in the shortwave infrared spectral region between 1 μm and 2 μm. The receiver measures the laser radiance reflected from the lunar surface in each spectral band and continuum/absorption reflectance band ratios are then analyzed to quantify water ice concentration in the illuminated spot. The receiver utilizes a 70×70-mm, aluminum, off-axis paraboloidal mirror with a focal length of 70 mm, which collects the incoming light onto a single, 2 mm diameter InGaAs detector with a cutoff wavelength of 2.4 μm. We present the optical and mechanical designs of the receiver, including its optimization for rejection of solar stray-light from outside its intended field of view. This highly mass- and volume-constrained instrument payload will demonstrate several firsts, including being one of the first instruments onboard a CubeSat performing science measurements beyond low Earth orbit and the first planetary mission to use multi-band active reflectometry from orbit.
The Snow and Water Imaging Spectrometer (SWIS) is a fast, high-uniformity, low-polarization sensitivity imaging spectrometer and telescope system designed for integration on a 6U CubeSat platform. Operating in the 350-1700 nm spectral region with 5.7 nm sampling, SWIS is capable of simultaneously addressing the demanding needs of coastal ocean science and snow and ice monitoring. New key technologies that facilitate the development of this instrument include a linear variable anti-reflection (LVAR) detector coating for stray light management, and a single drive on-board calibration mechanism utilizing a transmissive diffuser for solar calibration. We provide an overview of the SWIS instrument design and potential science applications and describe the instrument assembly and alignment, supported by laboratory measurements.
The Snow and Water Imaging Spectrometer (SWIS) is a fast, high-uniformity, low-polarization sensitivity imaging spectrometer and telescope system designed for integration on a 6U CubeSat platform. Operating in the 350-1700 nm spectral region with 5.7 nm sampling, SWIS is capable of simultaneously addressing the demanding needs of coastal ocean science and snow and ice monitoring. New key technologies that facilitate the development of this instrument include a linear variable anti-reflection (LVAR) detector coating for stray light management, and a single drive on-board calibration mechanism utilizing a transmissive diffuser for solar calibration. We provide an overview of the SWIS instrument design, spacecraft configuration design, and potential science missions.
The Snow and Water Imaging Spectrometer (SWIS) is a fast, high-uniformity, low-polarization sensitivity imaging spectrometer and telescope system designed for integration on a 6U CubeSat platform. Operating in the 350-1700 nm spectral region with 5.7 nm sampling, SWIS is capable of simultaneously addressing the demanding needs of coastal ocean science and snow/ice monitoring. We discuss progress in the SWIS optomechanical design, thermal analysis, and mission plan. We also describe an innovative single drive on-board calibration system capable of addressing the stringent radiometric stability and knowledge these missions require. The spectrometer features a new Teledyne CHROMA array, optimized for high temperature operation, with a linear variable anti-reflection coating to enhance quantum efficiency and minimize backscatter.
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