Arcus is a high-resolution soft X-ray and far-ultraviolet spectroscopy mission submitted to the National Aeronautics and Space Administration’s inaugural Astrophysics Probe solicitation. Arcus makes simultaneous observations in these two critical wavelength regimes to address a broad range of science questions highlighted by the 2020 Astronomy and Astrophysics Decadal Survey, from the temperature and composition of the missing baryons in the intergalactic medium to the evolution of stars and their influence on orbiting planets. We present the science motivation for and performance of the Arcus ultraviolet spectrograph (UVS). UVS comprises a 60-cm, off-axis Cassegrain telescope feeding an imaging spectrograph operating over the 970- to 1580-Å bandpass. The instrument employs two interchangeable diffraction gratings to provide medium-resolution spectroscopy (R>20,000 in two grating modes centered at ∼1110 and 1390 Å). The spectra are recorded on an open-face, photon-counting microchannel plate detector. The instrument design achieves an end-to-end sensitivity >10 times that of the Far-Ultraviolet Spectroscopic Explorer over the key 1020- to 1150-Å range and offers arcsecond-level angular resolution spectral imaging over a 6-arcminute-long slit for observations of extended sources. We describe the example science investigations for far-ultraviolet spectroscopy on Arcus, the resultant instrument design and predicted performance, and simulated data from potential General Observer programs with Arcus.
The National Aeronautics and Space Administration’s (NASA) first dedicated exoplanetary spectroscopy mission, the Colorado Ultraviolet Transit Experiment (CUTE), is used to search for signatures of atmospheric escape, the process by which constituent gases depart a planetary atmosphere. Through transit spectroscopy, the signs of escape driven by the high level of ultraviolet (UV) radiation from their parent stars are detectable around close-in planets. CUTE is a 6U CubeSat developed and operated by the Laboratory for Atmospheric and Space Physics (LASP) of the University of Colorado in Boulder, Colorado, United States; it looks for these signs of escape by surveying close-in extrasolar planets in the near-UV (2479 to 3306 Å) with 208×84 mm Cassegrain telescope-fed, UV-enhanced charged coupled device. Funded through a NASA ROSES proposal in 2017 and forced to deal with a worldwide pandemic during the heart of its fabrication and test program, CUTE has demonstrated the capability of small satellites to launch on schedule and perform challenging astronomical measurements. We will highlight the CUTE mission’s science objectives, implementation, and tribulations on its road to delivering a successful science program while discussing lessons learned pertaining to the development of CubeSat programs and the application of those lessons for a CUTE-style follow-on mission in the future.
The Arcus Probe is designed to measure the feedback cycle of material into and out of galaxies, and the inter-relation between these flows and the central black holes that drive many of these processes. Arcus consists of a high-resolution x-ray spectrometer (led by the Smithsonian Astrophysics Observatory; SAO) with a companion medium resolution (R ~ 24,500) far-ultraviolet imaging spectrograph covering the 970 - 1580 Å bandpass. The Arcus Ultraviolet Spectrograph (UVS) is designed in part to be a sucessor to the successful FUSE mission, with more than five-times the sensitivity in the essential Lyman UV, including rest-frame O VI 1032 ˚A, than any previous medium resolution spectroscopic instrument. The instrument consists of a 60 cm off-axis Cassegrain telescope feeding a two-channel spectrograph, with the spectra recorded on an open-face microchannel plate detector. The channels each consist of a medium resolution grating mounted to a grating selector: the G110M (970 - 1280 Å, optimized for 1000 - 1280 Å) and the G140M (1195 - 1580 Å). The Arcus UVS is led by the University of Colorado Laboratory for Atmospheric and Space Physics (LASP) and incorporates several technologies developed in the more than two decades since F USE, and matured on previous CU-LASP flight programs, including enhanced lithium fluoride protected aluminum mirror coatings (eLiF) and large-format borosilicate glass MCPs. We describe the recent development and TRL advancement of these enabling technologies, and then outline the UVS instrument and projected performance.
The Extreme-ultraviolet Stellar Characterization for Atmospheric Physics and Evolution (ESCAPE) mission is an astrophysics Small Explorer employing ultraviolet spectroscopy (EUV: 80 to 825 Å and FUV: 1280 to 1650 Å) 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 that directly impact the habitability of rocky exoplanets. In a 20-month science mission, ESCAPE will provide the essential stellar characterization to identify exoplanetary systems most conducive to habitability and provide a roadmap for NASA’s 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. The ESCAPE science instrument builds on previous ultraviolet and x-ray instrumentation, grazing incidence optical systems, and photon-counting ultraviolet detectors used on NASA astrophysics, heliophysics, and planetary science missions. The ESCAPE spacecraft bus is the versatile and high-heritage Ball Aerospace BCP-Small spacecraft. Data archives will be housed at the Mikulski Archive for Space Telescopes.
The Extreme-ultraviolet Stellar Characterization for Atmospheric Physics and Evolution (ESCAPE) mission is an astrophysics Small Explorer employing ultraviolet spectroscopy (EUV: 80 - 825 Å and FUV: 1280 - 1650 Å) 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 20 month science mission, ESCAPE will provide the essential stellar characterization to identify exoplanetary systems most conducive to habitability and provide a roadmap for NASA's 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. The ESCAPE science instrument builds on previous ultraviolet and X-ray instrumentation, grazing incidence optical systems, and photon-counting ultraviolet detectors used on NASA astrophysics, heliophysics, and planetary science missions. The ESCAPE spacecraft bus is the versatile and high-heritage Ball Aerospace BCP-Small spacecraft. Data archives will be housed at the Mikulski Archive for Space Telescopes (MAST). ESCAPE is currently completing a NASA Phase A study, and if selected for Phase B development would launch in 2025.
The University of Colorado led Extreme-ultraviolet Stellar Characterization for Atmospheric Physics and Evolution (ESCAPE) small explorer mission concept is designed to measure the extreme- and far-ultraviolet (EUV; 80 - 560 A, 600 - 825 A, FUV; 1280 - 1650 A) irradiance and are activity of exoplanet host stars; essential measurements for assessing the stability of rocky planet atmospheres in the liquid-water habitable zone. The ESCAPE design consists of a fixed optical configuration with a grazing incidence Gregorian, or "Hetterick- Bowyer", telescope feeding grazing and normal incidence spectroscopic channels. The telescope is provided by a joint NASA Marshall Space Flight Center and Smithsonian Astrophysics Observatory team. The grazing incidence gratings have a radial profile and are ruled into single-crystal silicon using electron-beam lithography in the nanofabrication laboratory at Pennsylvania State University. Normal incidence gratings have aberration correcting holographic solutions and are supplied by Horiba Jobin Yvon. Spectra are imaged onto a curved microchannel plate detector supplied by the University of California, Berkeley. ESCAPE utilizes the Ball Aerospace BCP spacecraft. The simple, fixed configuration design of ESCAPE is projected to exceed the effective area of the last major EUV astrophysics spectrograph, EUV E-DS/S, by more than a factor of 50, providing unprecedented sensitivity in this essential bandpass for exoplanet host-star characterization. We report on the ESCAPE design, projected performance and mission implementation plan, as well as the trade studies carried out over Phase A to scope the first NASA EUV astrophysics mission in nearly 30 years. If selected, ESCAPE will launch in Fall 2025.
The Extreme-ultraviolet Stellar Characterization for Atmospheric Physics and Evolution (ESCAPE) mission is an astrophysics Small Explorer employing ultraviolet spectroscopy (EUV: 80 – 825 Å and FUV: 1280 – 1650 Å) 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).
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