We describe the space observatory architecture and mission design of the Single Aperture Large Telescope for Universe Studies (SALTUS) mission, a NASA Astrophysics Probe Explorer concept. SALTUS will address key far-infrared science using a 14-m diameter <45 K primary reflector (M1) and will provide unprecedented levels of spectral sensitivity for planet, solar system, and galactic evolution studies, and cosmic origins. Drawing from Northrop Grumman's extensive NASA mission heritage, the observatory flight system is based on the LEOStar-3 spacecraft platform to carry the SALTUS Payload. The 14-m M1 is an off-axis inflatable membrane radiatively cooled by a two-layer sunshield. The SALTUS 5-year mission lifetime is driven by a two-consumable architecture: the propellant system and the inflation control system. The Core Interface Module, a multi-faceted composite truss structure, provides a load path with high stiffness, mechanical attachment, and thermal separation between the Payload and spacecraft. The spacecraft maintains an attitude off M1's boresight with respect to the Sun line to facilitate the <45 K thermal environment. SALTUS will reside in a Sun-Earth halo L2 orbit. The instantaneous field of regard provides two continuous 20° viewing zones around the ecliptic poles resulting in full sky coverage in six months.
We describe the space observatory architecture and mission design of the Single Aperture Large Telescope for Universe Studies (SALTUS) mission, a National Aeronautics and Space Administration (NASA) Astrophysics Probe Explorer concept. SALTUS will address key far-infrared science using a 14-m diameter <45 K primary reflector (M1) and will provide unprecedented levels of spectral sensitivity for planet, solar system, and galactic evolution studies and cosmic origins. Drawing from Northrop Grumman’s extensive NASA mission heritage, the observatory flight system is based on the LEOStar-3 spacecraft platform to carry the SALTUS Payload. The Payload is comprised of the inflation control system, sunshield module (SM), cold corrector module (CCM), warm instrument electronics module, and primary reflector module (PRM). The 14-m M1 is an off-axis inflatable membrane radiatively cooled by a two-layer sunshield (∼1000 m2 per layer). The CCM corrects for residual aberration from M1 and delivers a focused beam to two instruments—the High-Resolution Receiver (HiRX) and SAFARI-Lite. The CCM and PRM reside atop a truss-based composite deck that also provides a platform for the attitude control system. The SALTUS 5-year mission lifetime is driven by a two-consumable architecture: the propellant system and the inflation control system. The core interface module (CIM), a multi-faceted composite truss structure, provides a load path with high stiffness, mechanical attachment, and thermal separation between the Payload and spacecraft. The SM attaches outside the CIM with its aft end integrating directly to the bus. The spacecraft maintains an attitude off M1’s boresight with respect to the Sun line to facilitate the <45 K thermal environment. SALTUS will reside in a Sun–Earth halo L2 orbit with a maximum Earth slant range of 1.8 million km, thereby reducing orbit transfer delta-v. The instantaneous field of regard provides two continuous 20 deg viewing zones around the ecliptic poles, resulting in full sky coverage in 6 months.
The Arcus Probe mission addresses a wide range of Astro2020 Decadal and NASA Science Mission Directorate Priority science areas, and is designed to explore astrophysical feedback across all mass scales. Arcus' three baseline science goals include: (i) Characterizing the drivers of accretion-powered feedback in supermassive black holes, (ii) Quantifying how feedback at all scales drives galaxy evolution and large-scale structure, including the tenuous cosmic web, and (iii) Analyzing stellar feedback from exoplanetary to galactic scales, including its effects on exoplanet environments targeted by current and future NASA missions. These science goals, along with a robust General Observer program, will be achieved using a mission that provides a high-sensitivity soft (10-60Å) X-ray spectrometer (XRS), working simultaneously with a co-aligned UV spectrometer (UVS; 970-1580Å). Arcus enables compelling baseline science and provides the broader astronomy community a revolutionary tool to characterize the full ionization range of warm and hot plasmas - including hydrogen, helium, and all abundant metals - in the Universe, from the halos of galaxies and clusters to the coronae of stars.
HEX-P is an x-ray probe-class mission concept that will combine high angular resolution (⪅15 arcsec) with broad band spectral coverage (0.2 - 80 keV) to enable revolutionary new insights into the important astrophysical questions of the next decade identified by the 2020 Decadal Survey. Sensitivity is key to the instrument performance and estimating the background a crucial step in the development of the design and prediction of the instrument performance. The HEX-P orbit is at L1, and since L1 has hosted no prior missions with x-ray coverage that can be used to estimate the background level, the particle background has to be simulated. We present here the simulations done to evaluate the contribution to the background from charged particles, which show that the high energy background is dominated by hadronic activation in the detector mass and prompt leptons. To reduce the additional Cosmic X-ray Background (CXB), which is non-charged, the instruments are fitted with apertures and blocking plates of a graded-Z material to attenuate the CXB to a level an order of magnitude below the requirement.
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