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The INtegral Field Ultraviolet Spectroscopic Experiment (INFUSE), a sounding rocket payload under development at the University of Colorado Laboratory for Atmospheric and Space Physics, will be the first far ultraviolet (1000 - 2000 A° ) integral field spectrograph (IFS) in space. With access to part of the Lyman ultraviolet (1000 - 1216 A° ), INFUSE will study spectral emission lines such as O VI in extended objects at greater spatial resolution and grasp than has previously been possible. An F/16, 0.49 m Cassegrain telescope feeds the instrument. A 26-element image slicer provided by Canon Inc. forms the basis for the IFS. Each reflective slice acts as a long-slit, creating 26 different channels. Each channel is re-focused and dispersed by one of 26 identical holographic gratings supplied by Horiba JY onto the same 94 x 94 mm cross-strip (XS) microchannel plate detector (MCP). This MCP, provided by Sensor Sciences, will be the largest MCP of its type ever flown in space and will be advancing high event rate photon-counting detector technology for future NASA missions. We discuss the process of aligning the instrument, with a focus on the method by which the 26 gratings are aligned with the image slicer. Additionally, we examine the challenges presented by mounting and coating the large primary mirror and the steps taken to ensure that the mirror remains stable in flight. The first flight of INFUSE is projected for Spring 2023 when it will spectroscopically image the XA region of the Cygnus Loop at the interface between the supernova and the ambient ISM, studying shock fronts in the supernova remnant.

SPRITE, the first NASA-funded 12U CubeSat for astrophysics science, will use an ultraviolet light spectrograph with a photon-counting microchannel plate detector to provide spatial and spectral data on the light observed from low-redshift galaxies, active galactic nuclei, and shocked emission features of supernova remnants in the 1000Å − 1750Å bandpass. This proceedings describes recent progress on the design, implementation, and experimental evaluation of SPRITE’s electrical subsystems, particularly the high voltage power supply required to drive the microchannel plate detector. Measured experimental results for the commercial high voltage power supply module and the electronics board designed and built to control it are presented and discussed. The average voltage and voltage ripple of the high voltage power supply output when driving a resistive load that simulates the load anticipated on orbit due to the detector and a parallel voltage divider are presented. Planned revisions to the SPRITE electronics design are discussed, including modifications to be made to the high voltage power supply control board and the addition of an electronics board to handle all the interfaces between the command and data handling subsystem and the instrument electrical subsystems. SPRITE is planned to launch in early 2023 and will provide on-orbit data for the microchannel plate detector and other technologies onboard that are candidates for use on future large missions.

Slated to launch in early 2023, Supernova Remnants and Proxies for Re-Ionization Testbed Experiment (SPRITE) is the first NASA funded 12U astrophysics CubeSat payload and the first orbital astrophysics instrument to operate in the windowless Far-ultraviolet (1000 - 1750 A) since the deployment of HST-COS. SPRITE is an imaging spectrograph with 10 arcsecond angular resolution, breaking new ground with scientific observations enabled by a compact microchannel plate detector system and advanced protected eLiF mirror coatings baselined for the LUVOIR Surveyor. To provide flexibility and customizability the spacecraft bus and spectrograph are all being designed in house at the Laboratory for Atmospheric and Space Physics. SPRITE features several unique mechanical subsystems such as the pump/purge system for the hermetically sealed detector housing, the release mechanism for the detector door, the release mechanism for the solar array, the solar panel design, and compact rectangular telescope. SPRITE's mechanical design meets all science requirements, the CubeSat specific requirements of commercial 12U dispenser systems, and NASA orbital debris limits. We present an overview of the design and development of the mechanical systems and mechanisms for SPRITE prior to the comprehensive design review (CDR).

The Normal-incidence Extreme Ultraviolet Photometer (NExtUP) is a smallsat mission concept designed to measure the EUV radiation conditions of exoplanet host stars, and F-M type stars in general. EUV radiation is absorbed at high altitude in a planetary atmosphere, in the exosphere and upper thermosphere, where the gas can be readily heated to escape temperatures. EUV heating and ionization are the dominant atmospheric loss drivers during most of a planet’s life. There are only a handful of accurately measured EUV stellar fluxes, all dating from Extreme Ultraviolet Explorer (EUVE) observations in the ‘90s. Consequently, current models of stellar EUV emission are uncertain by more than an order of magnitude and dominate uncertainties in planetary atmospheric loss models. NExtUP will use periodic and aperiodic multilayers on off-axis parabolic mirrors and a prime focus microchannel plate detector to image stars in 5 bandpasses between 150 and 900°A down to flux limits two orders of magnitude lower than reached by EUVE. NExtUP may also accomplish a compelling array of secondary science goals, including using line-of-sight absorption measurements to understand the structure of the local interstellar medium, and imaging EUV emission from energetic processes on solar system objects at unprecedented spatial resolution. NExtUP is well within smallsat weight limits, requires no special orbital conditions, and would be flown on a spacecraft supplied by MOOG Industries. It draws on decades of mission heritage expertise at SAO and LASP, including similar instruments successfully launched and operated to observe the Sun.

The Extreme-ultraviolet Stellar Characterization for Atmospheric Physics and Evolution (ESCAPE) mission is an astrophysics Small Explorer employing ultraviolet spectroscopy (EUV: 80 – 825 A and FUV: 1280 – 1650 A) to explore the high-energy radiation environment in the habitable zones around nearby stars. ESCAPE provides the first comprehensive study of the stellar EUV and coronal mass ejection environments which directly impact the habitability of rocky exoplanets. In a 21 month science mission, ESCAPE will provide the essential stellar characterization to identify exoplanetary systems most conducive to habitability and provide a roadmap for future life-finder missions. ESCAPE accomplishes this goal with roughly two-order-of-magnitude gains in EUV efficiency over previous missions. ESCAPE employs a grazing incidence telescope that feeds an EUV and FUV spectrograph, building on experience with ultraviolet and X-ray instrumentation, grazing incidence optical systems, and photon-counting ultraviolet detectors. The instrument builds on design and hardware heritage from numerous NASA UV astrophysics, heliophysics, and planetary science missions. The ESCAPE spacecraft bus is the versatile and high-heritage Ball Aerospace BCP-Smallspacecraft. Data archives are housed at the Mikulski Archive for Space Telescopes (MAST).

Microchannel plate sensors are widely used as photon counting imagers in many applications, including, astronomy, high energy physics, and remote sensing. Potential future NASA observatories with ultraviolet instruments, such as LUVOIR and HABEX, will require large area detectors (8k × 8k pixels) with large dynamic range (≥1 kHz/resel), high quantum efficiency (75% peak), and very low backgrounds (≤0.1 cts/sec/cm2 ). New microchannel plate technology combining borosilicate glass microcapillary arrays with high efficiency materials applied by atomic layer deposition are being developed with these goals in mind. Detectors with these microchannel plates can be made in large formats (up to 400 cm2 ) with focal plane matching, have high spatial resolution ( 110 nm range). New photocathodes, such as GaN and hybrid bialkali/alkali halide, have high quantum efficiencies over broadband wavelengths. Cross-strip anodes are well suited for large format detectors with high spatial resolution and high dynamic range requirements. Improvements to detector anodes and readout electronics have resulted in better spatial resolution (10×), output event rate (100×), and temporal resolution (1000×), all the while operating at lower gain (10×). Combining these developments can have a significant impact to potential future NASA sub-orbital and satellite instruments.

The University of Colorado ultraviolet sounding rocket program presents the motivation and design capabilities of the new Suborbital Imaging Spectrograph for Transition Region Irradiance from Nearby Exoplanet host stars (SISTINE). SISTINE is a pathfinder for future UV space instrumentation, incorporating advanced broadband refl ective mirror coatings and large format borosilicate microchannel plate detectors that address technology gaps identified by the NASA Cosmic Origins program. The optical design capitalizes on new capabilities enabled by these technologies to demonstrate optical pathlengths in a sounding rocket envelope that would otherwise require a prohibitive effective area penalty in the 1020 - 1150 A bandpass. This enables SISTINE to achieve high signal-to-noise observations of emission lines from planet-hosting dwarf stars with moderate spectral resolution (R ~ 10,000) and sub-arcsecond angular imaging. In this proceedings, we present the scientific motivation for a moderate resolution imaging spectrograph, the design of SISTINE, and the enabling technologies that make SISTINE, and future advanced FUV-sensitive instrumentation, possible.

The High-ORbit Ultraviolet-visible Satellite (HORUS) is a 2.4-meter class space telescope that will conduct a comprehensive and systematic study of the astrophysical processes and environments relevant for the births and life cycles of stars and their planetary systems, to investigate and understand the range of environments, feedback mechanisms, and other factors that most affect the outcome of the star and planet formation process. HORUS will provide 100× greater imaging efficiency and combines the resolution of STIS with the throughput of COS. The HORUS mission will contribute vital information on how solar systems form and whether habitable planets should be common or rare. It also will investigate the structure, evolution, and destiny of galaxies and the universe. This program relies on focused capabilities unique to space that no other planned NASA mission will provide: near-ultraviolet (UV)/visible (200-1100nm) wide-field (14′ square), diffraction-limited imaging; and high-sensitivity, high-resolution FUV (100- 320nm) spectroscopy. From its baseline orbit at L2 HORUS will enjoy a stable environment for thermal and pointing control, and long-duration target visibility. The core HORUS design will provide wide field of view imagery and high efficiency point source far-ultraviolet (FUV) spectroscopy using a combination of spectral selection and field sharing.