High-pressure oxygen is an integral part of fuel cell systems, many NASA in situ resource utilization concepts, and life support systems for extravehicular activity. Due to the limited information available for system designs over wide ranges of temperature and pressure, volumetric methods are applied to measure adsorption isotherms of O(2) and N(2) on NaX and NaY zeolites covering temperatures from 105 to 448 K and pressures up to 150 bar. Experimental data measured using two apparatuses with distinctly different designs show good agreement for overlapping temperatures. Excess adsorption isotherms are modeled using a traditional isotherm model for absolute adsorption with a correction for the gas capacity of the adsorption space. Comparing two models with temperature-dependent coefficients, a virial isotherm model provides a better description than a Toth isotherm model, even with the same number of parameters. With more virial coefficients, such as a cubic form in loading and quadratic form in reciprocal temperature, the virial model can describe all data accurately over wide ranges of temperature and pressure.
For NASA applications, high-pressure oxygen is an integral part of portable life support systems (PLSSs) for Extravehicular Activities (EVAs), some fuel cell systems and potential In Situ Resource Utilization (ISRU) systems. New high-pressure oxygen generation systems will be needed on the International Space Station (to enable EVAs after the Shuttle is retired), on a Lunar Lander (to use lower pressure cryogenic tanks as a source of high pressure oxygen for EVAs) and on a planetary habitat (to generate and store high pressure oxygen for extended periods of time). One of the candidate technologies for producing high-pressure oxygen, temperature swing adsorption (TSA) compression, offers many advantages but has a low technology readiness level. Evaluation of technical feasibility and safety issues, and specification of operating parameters of the compressor require the availability of fundamental equilibrium adsorption data. A cryogenic, highpressure volumetric equilibrium adsorption apparatus has been developed at NASA Ames Research Center to facilitate collection of the needed data. The apparatus incorporates cryogenic and vacuum surrounds, and a high-pressure oxygen circuit. In this paper, lowtemperature equilibrium isotherms of oxygen on various sorbent materials are presented. The data presented will aid the development of a space qualified TSA system.
The mid-infrared spectrometer and camera transit spectrometer (MISC-T) is one of the three baseline instruments for Origins Space Telescope (Origins) and provides the capability to assess the habitability of nearby exoplanets and search for signs of life. MISC-T employs a densified pupil optical design, and HgCdTe and Si:As detector arrays. This optical design allows the instrument to be relatively insensitive to minor line-of-sight pointing drifts and telescope aberrations, and the detectors do not require a sub-Kelvin refrigerator. MISC-T has three science spectral channels that share the same field-of-view by means of beam splitters, and all channels are operated simultaneously to cover the full spectral range from 2.8 to 20 μm at once with exquisite stability and precision (<5 ppm between 2.8 to 11 μm, <20 ppm between 11 and 20 μm). A Lyot-coronagraph-based tip-tilt sensor located in the instrument fore-optics uses the light reflected by a field stop, which corresponds to 0.3% of the light from the target, to send fine pointing information to the field steering mirror in the Origins telescope. An additional MISC Wide Field Imager (WFI) is studied as an upscope option for the Origins. MISC-WFI offers a wide field imaging (3 0 × 3 0) and low-resolution spectroscopic capability with filters and gratingprisms (grisms) covering 5 to 28 μm. The imaging capability of the MISC-WFI will be used for general science objectives. The low-resolution spectroscopic capability in MISC-WFI with a resolving power R (¼ λ∕Δλ) of a few hundreds will be used to measure the mid-infrared dust features and ionic lines at z up to ∼1 in the Origins mission's Rise of Metals and Black Hole
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