The Astro2020 decadal survey designated a large ultraviolet (UV)/optical/infrared strategic mission, the Habitable Worlds Observatory (HWO), as the top priority for space-based astronomy in the coming decade. HWO will pursue an ambitious program of exoplanetary discovery/characterization and cosmic origin astrophysics. The decadal survey report recognized that many of HWO’s galactic ecosystem, exoplanet, and stellar science goals require high-throughput imaging and spectroscopy at ultraviolet through optical wavelengths (100 to 1000 nm). Early conceptual designs for the UV spectrograph on HWO are based on the LUVOIR and HabEx concept study reports, with a multi-object spectrograph incorporating multiple grating modes at the core of the instrument, and a high-resolution echelle mode and UV imager also under study (collectively referred to as the HWO UltraViolet Instrument, UVI). Recently, the HWO project office has also initiated the study of a secondary integral-field spectrograph. Taken together, the HWO UV spectrographs require gratings of several types spanning from low-resolution, low-blaze-angle modes to the highest-resolution echelle types. It is necessary to develop advanced, aberration-correcting, high-efficiency, low-scatter diffraction gratings to support HWO’s need for a wide range of grating characteristics. These efforts leverage recent APRA and SAT programs that developed viable fabrication techniques for improving echelle gratings, realizing ultralow blaze angles, creating custom groove shapes on curved surfaces, and infusing these technologies into suborbital demonstration missions. The continuation of these studies will increase the performance and technology readiness level of UV gratings through improved fabrication processes and performance verification, thus directly addressing top-priority technology gaps. In addition, the gratings will be studied for incorporation into intermediate-scale missions for demonstration in a mission framework (e.g., class D) that exists between the suborbital and HWO level.

The MANTIS (Monitoring Activity of Nearby sTars with uv Imaging and Spectroscopy) observatory is a compact, multi-instrument small satellite designed for simultaneous extreme- (EUV; 100 - 560 Angstrom), far- (FUV; 1150-1800 Angstrom) and near-ultraviolet/visible (NUV/VIS; 2000-6400 Angstrom) spectroscopy of low-mass stars. The EUV optical system consists of a first-of-its-kind Hettrick-Bowyer grazing incidence telescope contributed by the Italian National Institute for Astrophysics (INAF) feeding an advanced e-beam lithographic etched variable line spacing grating developed at Pennsylvania State University (PSU). The resulting low-resolution spectrum is imaged on an advanced microchannel plate detector with a potassium iodide (KI) photocathode for extremely low background noise, resulting in a limiting sensitivity for MANTIS that exceeds that of the last EUV-sensitive astrophysics point-source spectrograph, the Deep Survey/Spectrometer (DS/S) on EUVE. The FUV and NUV/Optical channels are fed by a compact rectangular telescope that focuses onto a series of point-source apertures. The diverging beam is refocused and the FUV band dispersed by a holographic grating, then folded back onto the same detector as the EUV channel by a toroidal fold mirror. The zero-order light is picked off by a flat NUV grating, with the NUV/Optical spectrum recorded on an e2v CCD 42-10 detector. The MANTIS spacecraft is a custom build that leverages the experience derived from prior University of Colorado - LASP SmallSats for avionics, power, communications, and mechanical structure. MANTIS is projected to be completed in 2027 with an anticipated 2028 launch as an ESPA-class payload on a rideshare opportunity.

We present here the current state of a collection of promising ultraviolet technologies in preparation for the Habitable Worlds Observatory. Working with experts representing a significant number of groups working in the ultraviolet, we summarize some of the leading science drivers, present an argument for a 100-nm blue wavelength cutoff, and gather the current state of the art of UV technologies. We present the state of the art of contamination control, a crucial piece of the UV instrument plan. We explore next steps with individual technologies, as well as present paths forward with system-level testing and development.

The Rockets for Extended-source X-ray Spectroscopy (tREXS) grating spectrograph uses modules of reflection gratings to collect spectroscopic data from extended astronomical sources of soft X-rays. Two blazed master gratings were produced on silicon substrates with electron-beam lithography (EBL) and complementary nanofabrication processes that include KOH etching. Substrate-conformal imprint lithography (SCIL) was then used to create 191 replicas of the two grating masters for use in the flight instrument. Diffraction efficiency was measured for several replica gratings, which achieve a peak of $$ \varvec{>} $$ > 70% absolute efficiency near 0.22 keV and an average of $$ \varvec{\approx } $$ ≈ 50% absolute efficiency across the measured band, from 0.18 – 0.8 keV. Here we detail the nanofabrication of the grating masters, including the EBL parameters and tREXS-specific fabrication considerations, and the SCIL replication process used to generate the final instrument gratings. A discussion of grating characterization and areas for future improvement is also presented.

The next generation of reflection gratings for future high-energy space observatories needs a high degree of customization. Making such gratings will require the use of increasingly complex nanofabrication techniques. One of the current challenges we are investigating is the precise patterning of grooves onto curved substrates, which is needed for effective aberration-correction. We report on our use of electron-beam lithography to pattern large-format gratings on cylindrical substrates. We will discuss the fabrication steps involved, from the alignment of the substrate to the actual writing strategy, and we will summarize our characterization efforts based on interferometric measurements. Future steps will be discussed, including the patterning of a segmented X-ray mirror.

We experimentally observe photonic Landau levels that arise due to a strain-induced pseudomagnetic field in a silicon photonic crystal slab. The Landau levels are dispersive (i.e., they are not flat bands) due to the distortion of the unit cell by the strain. We employ an additional strain which induces a pseudoelectric potential to flatten them.

Improved X-ray/UV spectroscopy is needed for studies of exoplanet host systems, the evolution of galaxies, and the physics of extreme astrophysical conditions. Efficient, high-resolution X-ray / UV spectrometers would meet this need, but realizing such instruments, particularly in compact formats like SmallSats, are often gated by the fabrication of a grating that meets the size, shape, diffractive design, and performance requirements of the spectrometer. We report on an effort to make custom, high performance gratings on curved surfaces using electron-beam lithography (EBL). We have made modestly-sized gratings (39 mm X 20 mm) on cylindrical surfaces with sag comparable to that of a grazing-incidence optic (> 1 mm). Our approach uses interferometric measurements of diffracted orders to assess the fidelity of EBL in realizing the desired grating, providing a direct measurement of the technology's current capabilities and informing development efforts. We also report on the fabrication and testing of a diffractive silicon mirror operating at grazing incidence, as well as an optical design for a test of a novel, two-element spectrometer system.

The MANTIS (Monitoring Activity of Nearby sTars with uv Imaging and Spectroscopy) 16U CubeSat mission, led by the Laboratory for Atmospheric and Space Physics (LASP) at the University of Colorado Boulder, plans to characterize the high-energy stellar radiation that drives atmospheric photochemistry and escape on extrasolar planets by conducting simultaneous observations of exoplanet host stars at extreme-ultraviolet (100–1200A; EUV), far-ultraviolet (1300–2200A; FUV), near-ultraviolet (2200–3500A; NUV), and visible (3500–10000A; VIS) wavelengths. The science payload's two-telescope design enables simultaneous coverage over the entire UV passband and the first EUV astrophysics capability in over 20 years. An 8.5cm diameter grazing incidence telescope feeds a low-resolution EUV spectrograph while a 14x9cm rectangular Cassegrain telescope feeds a dichroic beamsplitter to divide the light into both an NUV/VIS and FUV channel. The MANTIS design, detector systems, spacecraft bus and mission operations build off of the heritage of the CUTE and SPRITE CubeSats developed by the MANTIS team. This proceeding overviews the design of the MANTIS instrument and general mission concept.