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- Lillis, Robert J., et al.
(author)
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MOSAIC: A satellite constellation to enable groundbreaking mars climate system science and prepare for human exploration
- 2021
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In: Planetary Science Journal. - : Institute of Physics (IOP). - 2632-3338. ; 2:5
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Journal article (peer-reviewed)abstract
- The Martian climate system has been revealed to rival the complexity of Earth's. Over the last 20 yr, a fragmented and incomplete picture has emerged of its structure and variability; we remain largely ignorant of many of the physical processes driving matter and energy flow between and within Mars' diverse climate domains. Mars Orbiters for Surface, Atmosphere, and Ionosphere Connections (MOSAIC) is a constellation of ten platforms focused on understanding these climate connections, with orbits and instruments tailored to observe the Martian climate system from three complementary perspectives. First, low-circular near-polar Sun-synchronous orbits (a large mothership and three smallsats spaced in local time) enable vertical profiling of wind, aerosols, water, and temperature, as well as mapping of surface and subsurface ice. Second, elliptical orbits sampling all of Mars' plasma regions enable multipoint measurements necessary to understand mass/energy transport and ion-driven escape, also enabling, with the polar orbiters, dense radio occultation coverage. Last, longitudinally spaced areostationary orbits enable synoptic views of the lower atmosphere necessary to understand global and mesoscale dynamics, global views of the hydrogen and oxygen exospheres, and upstream measurements of space weather conditions. MOSAIC will characterize climate system variability diurnally and seasonally, on meso-, regional, and global scales, targeting the shallow subsurface all the way out to the solar wind, making many first-of-their-kind measurements. Importantly, these measurements will also prepare for human exploration and habitation of Mars by providing water resource prospecting, operational forecasting of dust and radiation hazards, and ionospheric communication/positioning disruptions.
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- Chuang, Yi-De, et al.
(author)
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Modular soft x-ray spectrometer for applications in energy sciences and quantum materials
- 2017
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In: Review of Scientific Instruments. - : AIP Publishing. - 1089-7623 .- 0034-6748. ; 88:1
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Journal article (peer-reviewed)abstract
- Over the past decade, the advances in grating-based soft X-ray spectrometers have revolutionizedthe soft X-ray spectroscopies in materials research. However, these novel spectrometers are mostlydedicated designs, which cannot be easily adopted for applications with diverging demands. Here wepresent a versatile spectrometer design concept based on the Hettrick-Underwood optical scheme thatuses modular mechanical components. The spectrometer’s optics chamber can be used with gratingsoperated in either inside or outside orders, and the detector assembly can be reconfigured accordingly.The spectrometer can be designed to have high spectral resolution, exceeding 10 000 resolvingpower when using small source (∼1 µm) and detector pixels (∼5 µm) with high line density gratings(∼3000 lines/mm), or high throughput at moderate resolution. We report two such spectrometers withslightly different design goals and optical parameters in this paper. We show that the spectrometer withhigh throughput and large energy window is particularly useful for studying the sustainable energymaterials. We demonstrate that the extensive resonant inelastic X-ray scattering (RIXS) map of batterycathode material LiNi1/3Co1/3Mn1/3O2 can be produced in few hours using such a spectrometer.Unlike analyzing only a handful of RIXS spectra taken at selected excitation photon energies across theelemental absorption edges to determine various spectral features like the localized dd excitations andnon-resonant fluorescence emissions, these features can be easily identified in the RIXS maps. Studyingsuch RIXS maps could reveal novel transition metal redox in battery compounds that are sometimeshard to be unambiguously identified in X-ray absorption and emission spectra. We propose that thismodular spectrometer design can serve as the platform for further customization to meet specificscientific demands.
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