Here we describe the design, prototyping, testing, and simulations that were conducted to demonstrate the technology for a concept of the next generation landed planetary spectral imager, the Europa Lander Stereo Spectral Imaging Experiment (ELSSIE). The concept was developed originally for a Europa Lander mission, but the design is applicable, with simplifications, to any ocean world of the outer solar system or to non-icy bodies, including Enceladus, the Moon, Mars, or the surface of Ceres. ELSSIE's design consists of two subassemblies. A Sensor melds a high-resolution, 20 -filter, 0.4-3.65 mu m, adjustable-focus multispectral stereo imager with a 0.8-3.6 mu m point spectrometer, sharing a radiation-shielded single Teledyne H2RG 2048 x 2048 pixel focal plane array (FPA). Each camera includes two 6 -position filter wheels with 5 filters and a blank position, providing 10 bandpasses for each of the 2 stereo eyes, and uses 700 x 700 pixels of the FPA. The point spectrometer uses a 6 x350 pixel strip of the FPA. The Sensor provides stereo and imaging/spectroscopic measurements of reflected light from visible to medium wave-infrared (MWIR) wavelengths to characterize surface morphology, search for pyroclastic plumes, search for organics, identify salts and possible biominerals, characterize crystalline vs. amorphous ice and ice grain sizes, and map the distributions of key phases. In addition to addressing important geologic questions, these measurements support selection of a site for in situ sampling and analysis. A Data Processing Unit (DPU) performs mitigation of radiation that penetrates the shielding using sets of same -filter image frames or spectra of a single spot by removing image spatial pixels with radiation hits, and coadding the remainder for the same spatial pixel, improving signal -to -noise ratio (SNR). The DPU also performs onboard calibration of imager and spectrometer data, co -registration of multispectral images, and calculation of spectral index ("summary parameter") images for efficient use of lander downlink. Co-registered multispectral image sets and spectra are retained onboard and can be downlinked upon query.

A framework for additive manufacturingAdditive manufacturing aluminum alloyAluminum alloys selection was developed to determine the preferred composition and process parametersProcess parameters from which to fabricate topology-optimized optical instrument housings and light-weighted freeform mirrors for the Compact Hyperspectral Air Pollution Sensor (CHAPS). In recent years, a number of high-strength laser powder bed fusionLaser-powder bed fusion aluminum alloysAluminum alloys have become commercially available, which are attractive for aerospace applications due to their high specific strength. Three aluminum alloysAluminum alloys were selected for a three-Round experimental comparison. Each Round used a down-selected subset of alloys and parameter sets (candidates) from the previous Round. Round 1 screened a wide range of laserLaser parameter sets for those that produced the highest density and tensile yield strength. Round 2 evaluated build quality using test geometries representative of CHAPS and assessed compatibility with post-processingProcessing, including optically black coatingCoating for the optical housings and nickelNickelphosphorus plating for the mirrors. Round 3 characterized anisotropyAnisotropy in tensile and thermal properties. A rating system was developed which involved assigning priority weighting for CHAPS-specific criteria and binning test results into scoring categories to give a comparison score for each candidate which was used in the down-selection between Rounds. The framework selection process enabled a comparison of the relative strengths and weaknesses of each candidate and resulted in the selection of Scalmalloy as the preferred alloy for CHAPS. The selected candidate was used to develop designDesign allowables for the topology optimization of CHAPS prototype housings, which were then fabricated.

Adverse air quality impacts human health and climate and has implications for environmental equity. The Compact Hyperspectral Air Pollution Sensor (CHAPS) is a newly designed small imaging spectrometer for remote sensing of nitrogen dioxide (NO2) and other air pollutants from space. It incorporates two emerging technologies, to achieve the miniaturization necessary to fit within a 6U CubeSat. The first is freeform optics, which can be used to reduce the size of an imaging spectrometer without compromising optical performance. We report the science requirements; preliminary, fully freeform and fully reflective optical design of the CHAPS demonstrator, CHAPS-D; and model its performance. The second technology is additive manufacturing, coupled with topology optimization, which has a number of potential advantages over traditional subtractive manufacturing. The instrument mechanical structure, including optical mounts and integral light baffles, and two of the optical elements will be additively manufactured using a high-strength nextgeneration aluminum alloy. We show preliminary results of additive manufacturing tests. CHAPS-D is currently being developed for ground-based and airborne testing.

We report on the calibration of the Compact Midwave Imaging Sensor (CMIS) which has been developed by The Johns Hopkins University - Applied Physics Lab (JHU/APL) under a grant from the NASA Earth Science Technology Office (ESTO). At the heart of the CMIS instrument is a newly-developed high operating temperature (HOT) detector made from III-V compounds in a Type II Superlattice design. The instrument is sensitive to 3 particular bands in the IR spectrum which have been noted for their usefulness in determining cloud coverage and temperatures. The bands used were centered at 2.25 μm, 3.75 μm and 4.05 μm. The focal plane array (FPA) was based on the FLIR ISC0405 640×512 pixel readout integrated circuit with 15 μm square pixels. The CMIS design included a 5 zone “butcher block” filter placed in close proximity to the FPA and refractive optical elements contained inside the barrel of the cold shield such that the optics were cooled to approximately the same temperature as the FPA. A small-size, low-power closed-cycle cooler was used to maintain the FPA and the optics at a temperature of 150 K, at which the dark current was low enough to allow integration times longer than 50 ms for cold background scenes. JHU/APL developed the camera control electronics (CCE) and data processing unit (DPU) for running the FPA, performing image processing functions on the data and storing it in memory. The CCE and DPU were designed for possible use on an orbital payload but for the airborne flight the commercial versions of some of the parts specified for spaceflight were used. This paper will describe the laboratory calibration procedures and results.

The Johns Hopkins University Applied Physics Laboratory (JHU/APL) is developing a compact, light-weight, and low-power midwave-infrared (MWIR) imager called the Compact Midwave Imaging Sensor (CMIS), under the support of the NASA Earth Science Technology Office Instrument Incubator Program. The goal of this CMIS instrument development and demonstration project is to increase the technical readiness of CMIS, a multi-spectral sensor capable of retrieving 3D winds and cloud heights 24/7, for a space mission. The CMIS instrument employs an advanced MWIR detector that requires less cooling than traditional technologies and thus permits a compact, low-power design, which enables accommodation on small spacecraft such as CubeSats. CMIS provides the critical midwave component of a multi-spectral sensor suite that includes a high-resolution Day-Night Band and a longwave infrared (LWIR) imager to provide global cloud characterization and theater weather imagery. In this presentation, an overview of the CMIS project, including the high-level sensor design, the concept of operations, and measurement capability will be presented. System performance for a variety of different scenes generated by a cloud resolving model (CRM) will also be discussed.

The Johns Hopkins University Applied Physics Laboratory (JHU/APL) has created a unique design for a compact, lightweight, and low-power instrument called the Compact Midwave Imaging Sensor (CMIS). Funded by the NASA ESTO Instrument Incubator Program (IIP), the goal of this CMIS development project is to increase the technical readiness of CMIS for retrieval of cloud heights and atmospheric motion vectors using stereo-photometric methods. The low-cost, low size, weight and power (SWaP) CMIS solution will include high operating temperature (HOT) MWIR detectors and a very low power cooler to enable spaceflight in a 6U CubeSat. This paper will provide an overview of the CMIS project to include the high-level sensor design.

Commercial space activities that utilize large space-based constellations provide a new and cost effective opportunity to acquire multi-point observations. Previously, a custom designed space-based constellation, while technically feasible, would require a substantial monetary investment. However, commercial industry has now been entertaining the concept of hosting payloads on their space-based constellations resulting in low-cost access to space. Examples include the low Earth orbit Iridium Next constellation as well as communication satellites in geostationary orbit. In some of these constellations, data distribution can be provided in real time, a feature relevant to applications in the areas of space weather and disaster monitoring. Future small-satellite constellations and hosting on commercial satellite constellations also provide outstanding opportunities for Earth remote sensing applications. In particular, we consider multi-spectral weather sensors to address gaps in future terrestrial weather needs. We will present concepts for weather sensors that are very compact, low mass, and low power, and so they can easily be accommodated on micro-satellites and hosted payloads. In this construct, compact weather sensors enable a cost effective solution to terrestrial weather requirements using small satellite or hosted payloads.

The Europa Jupiter System Mission, an international joint mission recently studied by NASA and the European Space Agency, would directly address the origin and evolution of satellite systems and the water-rich environments of icy moons. In this article, we report on the scientific goals of the NASA-led part of the Europa Jupiter System Mission, the Jupiter Europa Orbiter, which would investigate the potential habitability of the ocean-bearing moon Europa by characterizing the geophysical, compositional, geological, and external processes that affect this icy world.

The LOng-Range Reconnaissance Imager (LORRI) is the high-resolution imaging instrument for the New Horizons mission to Pluto, its giant satellite Charon, its small moons Nix and Hydra, and the Kuiper Belt, which is the vast region of icy bodies extending roughly from Neptune’s orbit out to 50 astronomical units (AU). New Horizons launched on January 19, 2006, as the inaugural mission in NASA’s New Frontiers program. LORRI is a narrow-angle (field of view=0.29°), high-resolution (4.95 μrad pixels), Ritchey-Chrétien telescope with a 20.8-cm diameter primary mirror, a focal length of 263 cm, and a three-lens, field-flattening assembly. A 1,024×1,024 pixel (optically active region), thinned, backside-illuminated charge-coupled device (CCD) detector is used in the focal plane unit and is operated in frame-transfer mode. LORRI provides panchromatic imaging over a bandpass that extends approximately from 350 nm to 850 nm. LORRI operates in an extreme thermal environment, situated inside the warm spacecraft with a large, open aperture viewing cold space. LORRI has a silicon carbide optical system, designed to maintain focus over the operating temperature range without a focus adjustment mechanism. Moreover, the spacecraft is thruster-stabilized without reaction wheels, placing stringent limits on the available exposure time and the optical throughput needed to satisfy the measurement requirements.

Long-term measurements of the global distributions of clouds, trace gases, and surface reflectance are needed for the study and monitoring of global change and air quality. The Geostationary Imaging Fabry–Perot Spectrometer (GIFS) instrument is an example of a next-generation satellite remote sensing concept. GIFS is designed to be deployed on a geostationary satellite, where it can make continuous hemispheric imaging observations of cloud properties (including cloud top pressure, optical depth, and fraction), trace gas concentrations, such as tropospheric and boundary layer CO, and surface reflectance and pressure. These measurements can be made with spatial resolution, accuracy, and revisit time suitable for monitoring applications. It uses an innovative tunable imaging triple-etalon Fabry–Perot interferometer to obtain very high-resolution line-resolved spectral images of backscattered solar radiation, which contains cloud and trace gas information. An airborne GIFS prototype and the measurement technique have been successfully demonstrated in a recent field campaign onboard the NASA P3B based at Wallops Island, Virginia. In this paper, we present the preliminary GIFS instrument design and use GIFS prototype measurements to demonstrate the instrument functionality and measurement capabilities.

Long-term measurements of the global distributions of clouds, trace gases, and surface reflectance are needed for the study and monitoring of global change and air quality. The Geostationary Imaging Fabry–Perot Spectrometer (GIFS) instrument is an example of a next-generation satellite remote sensing concept. GIFS is designed to be deployed on a geostationary satellite, where it can make continuous hemispheric imaging observations of cloud properties (including cloud top pressure, optical depth, and fraction), trace gas concentrations, such as tropospheric and boundary layer CO, and surface reflectance and pressure. These measurements can be made with spatial resolution, accuracy, and revisit time suitable for monitoring applications. It uses an innovative tunable imaging triple-etalon Fabry–Perot interferometer to obtain very high-resolution line-resolved spectral images of backscattered solar radiation, which contains cloud and trace gas information. An airborne GIFS prototype and the measurement technique have been successfully demonstrated in a recent field campaign onboard the NASA P3B based at Wallops Island, Virginia. In this paper, we present the preliminary GIFS instrument design and use GIFS prototype measurements to demonstrate the instrument functionality and measurement capabilities.

The Pluto Energetic Particle Spectrometer Science Investigation (PEPSSI) comprises the hardware and accompanying science investigation on the New Horizons spacecraft to measure pick-up ions from Pluto’s outgassing atmosphere. To the extent that Pluto retains its characteristics similar to those of a “heavy comet” as detected in stellar occultations since the early 1980s, these measurements will characterize the neutral atmosphere of Pluto while providing a consistency check on the atmospheric escape rate at the encounter epoch with that deduced from the atmospheric structure at lower altitudes by the ALICE, REX, and SWAP experiments on New Horizons. In addition, PEPSSI will characterize any extended ionosphere and solar wind interaction while also characterizing the energetic particle environment of Pluto, Charon, and their associated system. First proposed for development for the Pluto Express mission in September 1993, what became the PEPSSI instrument went through a number of development stages to meet the requirements of such an instrument for a mission to Pluto while minimizing the required spacecraft resources. The PEPSSI instrument provides for measurements of ions (with compositional information) and electrons from 10 s of keV to ∼1 MeV in a 160°×12° fan-shaped beam in six sectors for 1.5 kg and ∼2.5 W.

NASA’s MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) mission will further the understanding of the formation of the planets by examining the least studied of the terrestrial planets, Mercury. During the one-year orbital phase (beginning in 2011) and three earlier flybys (2008 and 2009), the X-Ray Spectrometer (XRS) onboard the MESSENGER spacecraft will measure the surface elemental composition. XRS will measure the characteristic X-ray emissions induced on the surface of Mercury by the incident solar flux. The Kα lines for the elements Mg, Al, Si, S, Ca, Ti, and Fe will be detected. The 12° field-of-view of the instrument will allow a spatial resolution that ranges from 42 km at periapsis to 3200 km at apoapsis due to the spacecraft’s highly elliptical orbit. XRS will provide elemental composition measurements covering the majority of Mercury’s surface, as well as potential high-spatial-resolution measurements of features of interest. This paper summarizes XRS’s science objectives, technical design, calibration, and mission observation strategy.

The Mercury Dual Imaging System (MDIS) on the MESSENGER spacecraft will provide critical measurements tracing Mercury’s origin and evolution. MDIS consists of a monochrome narrow-angle camera (NAC) and a multispectral wide-angle camera (WAC). The NAC is a 1.5° field-of-view (FOV) off-axis reflector, coaligned with the WAC, a four-element refractor with a 10.5° FOV and 12-color filter wheel. The focal plane electronics of each camera are identical and use a 1,024×1,024 Atmel (Thomson) TH7888A charge-coupled device detector. Only one camera operates at a time, allowing them to share a common set of control electronics. The NAC and the WAC are mounted on a pivoting platform that provides a 90° field-of-regard, extending 40° sunward and 50° anti-sunward from the spacecraft + Z -axis—the boresight direction of most of MESSENGER’s instruments. Onboard data compression provides capabilities for pixel binning, remapping of 12-bit data into 8 bits, and lossless or lossy compression. MDIS will acquire four main data sets at Mercury during three flybys and the two-Mercury-solar-day nominal mission: a monochrome global image mosaic at near-zero emission angles and moderate incidence angles, a stereo-complement map at off-nadir geometry and near-identical lighting, multicolor images at low incidence angles, and targeted high-resolution images of key surface features. These data will be used to construct a global image base map, a digital terrain model, global maps of color properties, and mosaics of high-resolution image strips. Analysis of these data will provide information on Mercury’s impact history, tectonic processes, the composition and emplacement history of volcanic materials, and the thickness distribution and compositional variations of crustal materials. This paper summarizes MDIS’s science objectives and technical design, including the common payload design of the MDIS data processing units, as well as detailed results from ground and early flight calibrations and plans for Mercury image products to be generated from MDIS data.