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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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330 records · Page 19
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Numerical Modelling of Sublimation Losses During Sample Handling Within the Light WAVE Lunar Water Prospecting Instrument

NASA’s focus of exploring the Moon’s south pole under the Artemis program has placed new emphasis on characterizing the quantity and distribution of water ice and other volatiles present within the Moon’s permanently shadowed regions (PSRs), first measured during the 2009 LCROSS mission. NASA’s VIPER rover is the first of a series of prospecting missions to characterize this water ice resource. NASA’s Johnson Space Center (JSC) has developed the Light Water Analysis and Volatiles Extraction (Light WAVE) instrument shown in Figure 1 for a follow-on prospecting mission, designed to be a rover payload for water ice prospecting at various depths and locations within PSRs. A key source of error for lunar water prospecting instruments, including Light WAVE, is the loss of water in an icy regolith sample to the lunar vacuum via sublimation due to heating above its ice-stable temperature. This abstract and conference presentation discuss a sublimation model for Light WAVE’s sample crucible using COMSOL Multiphysics to assess the sublimation losses that would occur between sample collection from an external drill and sealing the sample within Light WAVE’s boiler.

Lunar Polar Water↗
NASA NTRSDate not supplied

Acoustic Emission Methods for the Health Evaluation of Integrated Pressure Components

At the request of the Pressure Systems Senior Discipline Expert, to overcome the access and detectable flaw size limitations of other nondestructive evaluation (NDE) methods for integrated components, a technique akin to seismology was advanced to perceive the earliest signs of cracking in titanium components before they escalate into serious issues. In this project we achieved a landmark in Acoustic Emission (AE) testing with the first NASA Probability of Detection (POD) study. This is an important first step to the certification of the AE method for flight components and was based on the testing of notched panels. By working closely with industry allies and employing approved methods from the boiler and pressure vessel sector, we not only met but surpassed all POD benchmarks with our test and acceptance criteria. In experiments involving solution heat-treated and aged 6Al-4V-Ti alloy tested with broadband sensors, we recorded a 96% success rate, with zero false positives reported. Our research shows that in some cases, AE testing can locate smaller cracks than other NDE methods. An industry tool for scaling results to full pressure vessels is highlighted. However, before applying our findings to NASA components, tests to validate the transfer functions are advised.

acoustic↗
NASA NTRSDate not supplied

Evaluating Diurnal Ozone Emissions: A Comparative Analysis of DSCOVR EPIC, PANDORA, and TOLNet Data for Space-Based Monitoring Assessment: A Case Study by ASDC

Stratospheric ozone occurs naturally in the upper atmosphere, forming a protective layer that shields us from the sun's harmful ultraviolet rays. Tropospheric ozone is not emitted directly into the air but is created by chemical reactions between nitrogen oxides (NOx) and volatile organic compounds (VOC). This reaction happens when pollutants emitted by cars, power plants, industrial boilers, refineries, chemical plants, and other sources chemically react in sunlight [1]. Therefore, increased levels of tropospheric ozone indicate the presence of pollutants in the air. While daily anthropogenic activity causes an increase of ground-level ozone, variation of stratospheric ozone changes happens much slower, so that variation of the total ozone column reflects the variation of the tropospheric column due to natural, e.g., wildfires and anthropogenic air pollution. Both total and tropospheric ozone column products are used in this study. The reflectance spectra measured by the Earth Polychromatic Imaging Camera (EPIC) instrument aboard the Deep Space Climate Observatory (DSCOVR) spacecraft are compared with a set of radiative transfer-derived lookup tables for the EPIC filter transmission functions and a wide range of ozone values to retrieve ozone with a maximum resolution of 18 km at the sub-satellite point [2]. EPIC provides total column ozone in level 2 and level 4 products and tropospheric column ozone in level 4 products. Both EPIC Ozone products [2] are available at the Atmospheric Science Data Center (ASDC) at NASA Langley Research Center [3, 4]. Pandora spectrometer instrument measures columnar amounts of trace gases in the atmosphere. These gases (O3, NO2, CH2O) absorb light from the sun at specific wavelengths in the ultraviolet-visible spectrum [5]. Using the theoretical solar spectrum as a reference, Pandora determines trace gas amounts using differential optical absorption spectroscopy (DOAS). Pandora ozone retrievals are available from the Pandonia Global Network [6]. Pandora data from North American major metropolitan areas, New York, NY, Washington DC, Los Angeles, CA, and Mexico City. Tropospheric Ozone Lidar Network (TOLNet) was established in 2012 to provide high spatiotemporal observations of tropospheric ozone to (1) better understand physical processes driving the ozone budget in various meteorological and environmental conditions and (2) validate the tropospheric ozone measurements of space-borne missions [7]. TOLNet data are available at ASDC [8]. While EPIC provides global coverage of ozone retrievals several times daily, temporal resolution may miss some features in daily ozone variations. Ground-based sensors such as Pandora spectrometers and TOLNet lidars provide better temporal resolution while missing continuous spatial coverage. The forthcoming ozone retrieval from the TEMPO mission [9] will provide better spatial and temporal coverage of air quality (including ozone) over North America. This study investigates whether EPIC ozone products can detect diurnal air quality variations and compare ozone temporal development with retrieval by ground-based instruments.

diurnal ozone emissions, DSCOVR EPIC, PANDORA, spa↗