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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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At least 1,063 records · Page 59
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Fundamental Factors Impacting the Stability of Phosphonate-Derivatized Ruthenium Polypyridyl Sensitizers Adsorbed on Metal Oxide Surfaces

A series of 18 ruthenium(II) polypyridyl complexes were synthesized and evaluated under electrochemically oxidative conditions, which generates the Ru(III) oxidation state and mimics the harsh conditions experienced during the kinetically limited regime that can occur in dye-sensitized solar cells (DSSCs) and dye-sensitized photo-electrosynthesis cells, to further develop fundamental insights into the factors governing molecular sensitizer surface stability in aqueous 0.1 M HClO 4 . Both desorption and oxidatively induced ligand substitution were observed on planar fluorine-doped tin oxide (FTO) electrodes, with a dependence on the E 1/2 Ru(III/II) redox potential dictating the comparative ratios of the processes. Complexes such as RuP4OMe ( E 1/2 = 0.91 vs Ag/AgCl) displayed virtually only desorption, while complexes such as RuPbpz ( E 1/2 > 1.62 V vs Ag/AgCl) displayed only chemical decomposition. Comparing isomers of 4,4'- and 5,5'-disubstituted-2,2'-bipyridine ancillary ligands, a dramatic increase in the rate of desorption of the Ru(III) complexes was observed for the 5,5'-ligands. Nanoscopic indium-doped tin oxide thin films (nanoITO) were also sensitized and analyzed with cyclic voltammetry, UV–vis absorption spectroscopy, and X-ray photoelectron spectroscopy, allowing for further distinction of desorption versus ligand-substitution processes. Desorption loss to bulk solution associated with the planar surface of FTO is essentially non-existent on nanoITO, where both desorption and ligand substitution are shut down with RuP4OMe. Finally, these results revealed that minimizing time spent in the oxidized form, incorporating electron-donating groups, maximizing hydrophobicity, and minimizing molecular bulk near the adsorbed ligand are critical to optimizing the performance of ruthenium(II) polypyridyl complexes in dye-sensitized devices.

14 SOLAR ENERGY↗
DOE OSTI2024

Temperature, Humidity, and Time-Lapse Video Data from the East River Watershed, Water Year 2024

A new version of this dataset is available at doi:10.15485/3001338 and is the first citation in the 'Related References' section. It is expands on this dataset by appending another water year of data collection and additional logger sites.This dataset contains time-lapse imagery and distributed measurements of air temperature, relative humidity, dew point, and soil temperature across the East River basin from 3 October 2023 to 12 August 2024. Instruments were deployed at 14 sites as part of the DOE Grant: Seasonal Cycles Unravel Mysteries of Missing Mountain Water organized by Jessica Lundquist (University of Washington), Rosemary Carroll (Desert Research Institute), and Ethan Gutmann (National Center for Atmospheric Research). The data are published to support studies of surface climate or hydrologic processes in complex terrain. Measurements were collected with low-cost data loggers installed 2 m high on evergreen trees or buried just below the soil surface. Time-lapse cameras were deployed at three sites. Imagery from sites AP BONUS and AP5 provides insight into large-scale seasonal snow cover variability. Imagery from site EL2 shows smaller-scale snow patterns across a nearby meadow.Dataset files are organized by site and variable (air measurements, ground measurements, or time-lapse video). Air and ground measurements are packaged in LoggerData.zip, and time-lapse imagery is compiled into short videos stored in TimelapseVideos.zip. File-level metadata contains details for each file included in the dataset. A data dictionary provides units and descriptions for column or row names in all files. The locations metadata file describes site characteristics, locations, and associated GPS methods.Dataset update 2025-03-03: Resolved header and datetime formatting inconsistencies within LoggerData.zip files KP1_Air, KP3_Air, KP3_Ground, KP6_Ground, AP3_Ground, AP4_Air, and AP6_Air.Dataset update 2025-11-18: Modified abstract and related references sections to include new version of dataset.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2024

Temperature, Humidity, and Time-Lapse Video Data from Yosemite National Park, Water Year 2024

This dataset contains time-lapse imagery and distributed measurements of air temperature, relative humidity, dew point, and soil temperature across Yosemite National Park from October 2023 to September 2024. Instruments were deployed at 10 sites in two cross-valley transects as part of the DOE Grant: Seasonal Cycles Unravel Mysteries of Missing Mountain Water organized by Jessica Lundquist (University of Washington), Rosemary Carroll (Desert Research Institute), and Ethan Gutmann (National Center for Atmospheric Research). The data are intended to support hydrologic modeling efforts to better resolve the fate of mountain water, and are published to support studies of surface climate or hydrologic processes in complex terrain. Measurements were collected with low-cost data loggers installed 2 m high on evergreen trees or buried just below the soil surface. A time-lapse camera at one site captures valley-scale seasonal snow cover variability.Dataset files are organized by site and variable (air measurements, ground measurements, or time-lapse video). Air and ground measurements are packaged in LoggerData.zip, and time-lapse imagery is compiled into a short video stored in TimelapseVideos.zip. File-level metadata contains details for each file included in the dataset. A data dictionary provides units and descriptions for column or row names in all files. The locations metadata file describes site characteristics, locations, and associated GPS methods.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2025

Temperature, Humidity, and Time-Lapse Video Data from the East River Watershed, Water Years 2024 and 2025

This dataset contains time-lapse imagery and distributed measurements of air temperature, relative humidity, dew point, and soil temperature across the East River basin from 3 October 2023 to 8 August 2025. Instruments were deployed at 19 sites as part of the DOE Grant: Seasonal Cycles Unravel Mysteries of Missing Mountain Water organized by Jessica Lundquist (University of Washington), Rosemary Carroll (Desert Research Institute), and Ethan Gutmann (National Center for Atmospheric Research). The data are published to support studies of surface climate or hydrologic processes in complex terrain. Measurements were collected with low-cost data loggers installed 2 m high on evergreen trees or buried just below the soil surface. Time-lapse cameras were deployed at three sites. Imagery from sites AP BONUS and AP5 (Avery Picnic) provides insight into large-scale seasonal snow cover variability. Imagery from site EL2 (Emerald Lake) shows smaller-scale snow patterns across a nearby meadow. Dataset files are organized by site and variable (air measurements, ground measurements, or time-lapse video). Air and ground measurements are packaged in LoggerData.zip, and time-lapse imagery is compiled into short videos stored in TimelapseVideos.zip. File-level metadata contains details for each file included in the dataset. A data dictionary provides units and descriptions for column or row names in all files. The locations metadata file describes site characteristics, locations, and associated GPS methods.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

Lithium-Ion Battery Materials as Tunable, “Redox Non-Innocent” Catalyst Supports

The development of general strategies for the electronic tuning of a catalyst’s active site is an ongoing challenge in heterogeneous catalysis. To this end, herein, we describe the application of Li-ion battery cathode and anode materials as redox non-innocent catalyst supports that can be continuously modulated as a function of lithium intercalation. A zero-valent nickel complex was oxidatively grafted onto the surface of lithium manganese oxide (Li x Mn 2 O 4 ) to yield isolated Ni2+ occupying the vacant interstitial octahedral site in the Li diffusion channel on the surface and subsurface of the spinel structure (Ni/Li x Mn 2 O 4 ). Additionally, the activity of Ni/Li x Mn 2 O 4 for olefin hydrogenation, as a representative probe reaction, was found to increase monotonically as a function of support reductive lithiation. Simulation of Ni/Li x Mn 2 O 4 reveals the dramatic impact of surface redox states on the viability of the homolytic oxidative addition mechanism for H 2 activation. Catalyst control through support lithiation was extended to an organotantalum complex on Li x TiO 2 , demonstrating the generality of this phenomenon.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRSDate not supplied

A window on the composition of the early solar nebula: 2014MU69, Pluto, and Phoebe

The initial chemical composition of any solar nebula will depend upon the degree to which 1) organic and ice components form on dust grains, 2) organic and molecular species form in the gas phase, 3) organics and ices are exchanged between the gas and solid state, and 4) the precursor and newly formed (more complex) materials survive and are modified in the developing planetary system. Infrared and radio observations of star-forming regions reveal that complex chemistry occurs on icy grains, sometimes before stars even form. Additional processing, through the protosolar disk and within the solar nebula further modifies most, but probably not all, of the initial materials. In fact, the modern Solar System still carries a fraction of its interstellar inheritance [Alexander et al., 2017]. Here we focus on three examples of small bodies in our Solar System, each containing chemical and dynamical clues to its origin and evolution: the small, cold-classical Kuiper Belt object (KBO) 2014MU69 , Pluto and Saturn’s moon, Phoebe. The New Horizons flyby of 2014 MU69 has given the first view of an unaltered body composed of material originally in the solar nebula at ~45 AU. The spectrum reveals methanol ice (not commonly found), a possible detection of water ice (Stern et al. 2019). Pluto’s internal and surface inventory of volatiles and complex organics, together with active geological processes including cryo-volcanism, indicate a surprising level of activity on a body in the outermost region of the Solar System, and the fluid that emerges from subsurface reservoirs may contain material inherited from the solar nebula (Cruikshank et al. 2019). Meanwhile, Saturn's captured moon, Phoebe, carries high D/H in H2O [Clark et al. 2018)], and complex organics (Cruikshank et al. 2008), both consistent with its formation in, and inheritance from, the outer solar nebula. Together, these objects provide windows on the origin and evolution of our Solar System and constraints to be considered in future chemical and physical models of PPDs. The Spitzer Space telescope discovered the ring of dust around Saturn that emanated from the bombardment of Phoebe in the recent past, dislodging primitive Solar System material from deep within that satellite. In addition, Spitzer has provided detailed studies of the chemistry of star forming regions where methanol and other ices are readily observed. As a result of these and other observations, protoplanetary disk models are beginning to combine both dynamical and chemical complexities into their codes, resulting in new insights for exoplanetary systems.

Yvonne J. Pendleton↗
DOE OSTI2025

Tuning 3-D Nanomaterial Architectures Using Atomic Layer Deposition to Direct Solution Synthesis

The ability to synthesize nanoarchitected materials with tunable geometries provides a means to control their functional properties, with applications in biological, environmental, and energy fields. To this end, various bottom-up and top-down synthesis processes have been developed. However, many of these processes require prepatterning or etching steps, making them challenging to scale-up to complex, nonplanar substrates. Furthermore, the ability to integrate nanomaterials into hierarchical arrays with precise control of feature spacing and orientation remains a challenge. One approach to overcome these patterning challenges is the use of surface modification layers to guide the resulting geometry of nanomaterial architectures grown from the substrate. A powerful strategy to accomplish this is what we will refer to as “surface-directed assembly,” where the resulting geometric parameters (feature size, shape, orientation) are predetermined by the initial surface layer. In particular, the use of Atomic Layer Deposition (ALD) to form a surface layer, followed by solution-based growth processes, has the ability to synthesize architected structures with tunable geometries on complex, nonplanar surfaces. Over the past decade, we have reported a series of studies where surface-directed assembly is used to synthesize ZnO nanowires (NWs) on top of a variety of substrates. In this case, a thin film of ZnO is deposited onto the substrate using ALD, which can guide the NW diameter, spacing, and angular orientation with respect to the substrate by controlling epitaxial relationships. Furthermore, we have shown that by depositing a submonolayer overcoat of a secondary material (e.g., amorphous TiO 2 ), nucleation sites are partially blocked, which can further tune the spacing between nanowires while minimizing changes to their other geometric properties. This approach can be used to generate multilevel hierarchical structures, such as hyperbranched NW arrays with tunable control of each level of hierarchy using ALD. Finally, we have demonstrated that the tunable control of geometric parameters can be scaled-up to curved, nonplanar substrates. This highlights the power of ALD to conformally and uniformly deposit the seed layers on complex substrates with subnanometer precision. To complement these seeded hydrothermal approaches, we expanded this strategy to include conversion chemistry of the initial ALD seed layers. For example, by replacing ZnO with Al 2 O 3 as the seed layer without changing the hydrothermal growth conditions, Al–Zn layered-double hydroxide nanosheets can be formed instead of nanowires. In another example of conversion chemistry, a solution anion-exchange process was used to incorporate sulfur into ALD metal oxide films. In both of these conversion processes, the properties of the initial ALD film enabled tuning of the resulting nanostructure geometry. In this Account, we describe the use of ALD to guide the growth of diverse nanomaterial systems, with tunable control over their geometry and composition. We further show how these approaches can be used to tune functional properties for a range of applications, including superomniphobic surfaces, antibiofouling coatings, and photocatalysis. In conclusion, we conclude with an outlook on how the combination of ALD and solution synthesis can enable future directions in scalable nanomanufacturing to overcome the limitations of traditional top-down and bottom-up approaches.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS2022

Titan In-situ Resource Utilization (ISRU) Sample Return (TISR)

Titan is unique in the outer solar system in that it is the only moon with a thick atmosphere, and the only body in the solar system outside the Earth with liquid seas on its surface. The Titanian oceans, however, are seas of liquid hydrocarbons, and the rocks on the surface are solid water ice. Like other icy Moons of the outer solar system, beneath the ice crust, Titan also has a subsurface ocean. Rodriguez et al. refer to it as the “world with two oceans”, an organic-rich body with interior-surface-atmosphere interactions that are comparable in complexity to the Earth. [1] Titan is scientifically fascinating in many ways [2], [3], [4]. The Compass Team will emphasize just one here: Titan is a high priority target for astrobiology [4] [5] [6] [7] [8] [9] [10] [11]. It is a world with a surface and atmosphere rich in the complex organic compounds known as tholins. A detailed understanding of the nature of these complex compounds will require an analysis using a full laboratory on Earth. Because of its value to understanding the organic compounds of the outer solar system which may be the primordial building-blocks of life, return of samples from Titan to laboratories on Earth will be the primary goal of this mission. While this would give unprecedented science return, returning even a small sample from Titan using conventional technology would be tremendously difficult. Saturn is almost a billion miles from the Earth, about thirteen times farther than Mars. A return mission to Saturn requires such a large total-mission ∆V that, with conventional technology, the mass ratios required are prohibitive. Such a sample return would truly be “mission incredible.” But to date, a sample return mission from so distant a target has been assumed to be, not merely incredible, but mission impossible. The Compass Team has proposed [2] [12] that by manufacturing the propellant for the return to Earth using the resources available on Titan, such a mission becomes possible. The task of this report is to show that it is reasonable with credible space technology.

Titan↗
DOE OSTI2021

Surface Reconstruction of Halide Perovskites During Post-treatment

Postfabrication surface treatment strategies have been instrumental to the stability and performance improvements of halide perovskite photovoltaics in recent years. However, a consensus understanding of the complex reconstruction processes occurring at the surface is still lacking. Here, we combined complementary surface-sensitive and depth-resolved techniques to investigate the mechanistic reconstruction of the perovskite surface at the microscale level. We observed a reconstruction toward a more PbI 2 -rich top surface induced by the commonly used solvent isopropyl alcohol (IPA). We discuss several implications of this reconstruction on the surface thermodynamics and energetics. Particularly, our observations suggest that IPA assists in the adsorption process of organic ammonium salts to the surface to enhance their defect passivation effects.

14 SOLAR ENERGY↗
DOE OSTI2022

Volumetric additive manufacturing of silica glass with microscale computed axial lithography

Glass is increasingly desired as a material for manufacturing complex microscopic geometries, from the micro-optics in compact consumer products to microfluidic systems for chemical synthesis and biological analyses. As the size, geometric, surface roughness, and mechanical strength requirements of glass evolve, conventional processing methods are challenged. We introduce microscale computed axial lithography (micro-CAL) of fused silica components, by tomographically illuminating a photopolymer-silica nanocomposite that is then sintered. We fabricated three-dimensional microfluidics with internal diameters of 150 micrometers, free-form micro-optical elements with a surface roughness of 6 nanometers, and complex high-strength trusses and lattice structures with minimum feature sizes of 50 micrometers. As a high-speed, layer-free digital light manufacturing process, micro-CAL can process nanocomposites with high solids content and high geometric freedom, enabling new device structures and applications.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Common Photo-oxidative Decarboxylation Mechanism in Iron Hydroxy Carboxylate Complexes

Photochemical oxidation of dissolved organic matter is a crucial component of carbon cycling in surface waters. Photo-oxidation of iron(III)-carboxylate complexes is of particular interest because complexation with iron(III) can sensitize this functional group to photodecarboxylation. Further, the photo-oxidation mechanism of ferrioxalate has been extensively characterized, but it is unclear whether the mechanism or timing is similar for other more complex carboxylates. In this study, we use time-resolved infrared spectroscopy to demonstrate that Fe(III)-citrate, an aliphatic carboxylate, and Fe(III)-salicylate, an aromatic carboxylate, follow the same photo-oxidation kinetics as ferrioxalate. Hence the data suggest a common mechanism for decarboxylation of iron hydroxy carbonates. Differences in the CO 2 yield within 50 ps are qualitatively similar to the long-time-scale quantum yield for Fe(II) production.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1995

The development of concentration gradients in a suspension of chemotactic bacteria

When a suspension of bacterial cells of the species Bacillus subtilis is placed in a chamber with its upper surface open to the atmosphere complex bioconvection patterns are observed. These arise because the cells: (1) are denser than water; and (2) usually swim upwards, so that the density of an initially uniform suspension becomes greater at the top than the bottom. When the vertical density gradient becomes large enough, an overturning instability occurs which ultimately evolves into the observed patterns. The reason that the cells swim upwards is that they are aerotactic, i.e., they swim up gradients of oxygen, and they consume oxygen. These properties are incorporated in conservation equations for the cell (N) and oxygen (C) concentrations, and these are solved in the pre-instability phase of development when N and C depend only on the vertical coordinate and time. Numerical results are obtained for both shallow- and deep-layer chambers, which are intrinsically different and require different mathematical and numerical treatments. It is found that, for both shallow and deep chambers, a thin boundary layer, densely packed with cells, forms near the surface. Beneath this layer the suspension becomes severely depleted of cells. Furthermore, in the deep chamber cases, a discontinuity in the cell concentration arises between this cell-depleted region and a cell-rich region further below, where no significant oxygen concentration gradients develop before the oxygen is fully consumed. The results obtained from the model are in good qualitative agreement with the experimental observations.

NASA Discipline Cell Biology↗
NASA NTRS1992

Multi-resolution processing for fractal analysis of airborne remotely sensed data

Fractal geometry is increasingly becoming a useful tool for modeling natural phenomenon. As an alternative to Euclidean concepts, fractals allow for a more accurate representation of the nature of complexity in natural boundaries and surfaces. Since they are characterized by self-similarity, an ideal fractal surface is scale-independent; i.e. at different scales a fractal surface looks the same. This is not exactly true for natural surfaces. When viewed at different spatial resolutions parts of natural surfaces look alike in a statistical manner and only for a limited range of scales. Images acquired by NASA's Thermal Infrared Multispectral Scanner are used to compute the fractal dimension as a function of spatial resolution. Three methods are used to determine the fractal dimension - Schelberg's line-divider method, the variogram method, and the triangular prism method. A description of these methods and the results of applying these methods to a remotely-sensed image is also presented. Five flights were flown in succession at altitudes of 2 km (low), 6 km (mid), 12 km (high), and then back again at 6 km and 2 km. The area selected was the Ross Barnett reservoir near Jackson, Mississippi. The mission was flown during the predawn hours of 1 Feb. 1992. Radiosonde data was collected for that duration to profile the characteristics of the atmosphere. This corresponds to 3 different pixel sizes - 5m, 15m, and 30m. After, simulating different spatial sampling intervals within the same image for each of the 3 image sets, the results are cross-correlated to compare the extent of detail and complexity that is obtained when data is taken at lower spatial intervals.

Jaggi, S.↗
DOE OSTI2018

Development of Broadband Microwave Absorber and Measurement of Its Magnetic and Microwave Properties

Toroid shape Co-doped barium hexaferrites of composition (BaFe{sub 11}CoO{sub 19}) are prepared by standard sintering technology as a sample. In this work, XRD is used to identify the structure of synthesized sample. Vibrating sample magnetometer is used to obtain magnetic hysteresis loop of sample. Scanning electron microscope is used for surface morphology of sample. The complex permeability and permittivity are measured with commercial automation measurement set up in the 2–18 GHz frequency range. As a result of measurement, the calculation of reflection loss of the synthesized samples has been carried out. Investigation of microwave absorption properties revealed that the maximum reflection loss of Co-doped barium hexaferrite sample is around −20 dB and almost flat in the measurement frequency band. From these results, it was concluded that Co-doped barium hexaferrites of composition had a good potential as microwave absorber in the broadband frequency range.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2022

Performance of New Near-Real-Time PERSIANN Product (PDIR-Now) for Atmospheric River Events over the Russian River Basin, California

Most heavy precipitation events and extreme flooding over the U.S. Pacific coast can be linked to prevalent atmospheric river (AR) conditions. Thus, reliable quantitative precipitation estimation with a rich spatiotemporal resolution is vital for water management and early warning systems of flooding and landslides over these regions. At the same time, high-quality near-real-time measurements of AR precipitation remain challenging due to the complex topographic features of land surface and meteorological conditions of the region: specifically, orographic features occlude radar measurements while infrared-based algorithms face challenges, differentiating between both cold brightband (BB) precipitation and the warmer nonbrightband (NBB) precipitation. It should be noted that the latter precipitation is characterized by greater orographic enhancement. In this study, we evaluate the performance of a recently developed near-real-time satellite precipitation algorithm: Precipitation Estimation from Remotely Sensed Information Using Artificial Neural Networks (PERSIANN) Dynamic Infrared–Rain Rate-Now (PDIR-Now). This model is primarily dependent on infrared information from geostationary satellites as input; consequently, PDIR-Now has the advantage of short data latency, 15–60-min delay between observation to precipitation product delivery. The performance of PDIR-Now is analyzed with a focus on AR-related events for cases dominated by NBB and BB precipitation over the Russian River basin. In our investigations, we utilize S-band (3-GHz) precipitation profilers with Joss/Parsivel disdrometer measurements at the Middletown and Santa Rosa stations to classify BB and NBB precipitation events. In general, our analysis shows that PDIR-Now is more skillful in retrieving precipitation rates over both BB and NBB events across the topologically complex study area as compared to PERSIANN-Cloud Classification System (CCS). Also, we discuss the performance of well-known operational near-real-time precipitation products from 2017 to 2019. Conventional categorical and volumetric categorical indices, as well as continuous statistical metrics, are used to show the differences between various high-resolution precipitation products such as Multi-Radar Multi-Sensor (MRMS).

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS2012

Supercritical CO2 Cleaning System for Planetary Protection and Contamination Control Applications

Current spacecraft-compatible cleaning protocols involve a vapor degreaser, liquid sonication, and alcohol wiping. These methods are not very effective in removing live and dead microbes from spacecraft piece parts of slightly complicated geometry, such as tubing and loosely fitted nuts and bolts. Contamination control practices are traditionally focused on cleaning and monitoring of particulate and oily residual. Vapor degreaser and outgassing bakeout have not been proven to be effective in removing some less volatile, hydrophilic biomolecules of significant relevance to life detection. A precision cleaning technology was developed using supercritical CO2 (SCC). SCC is used as both solvent and carrier for removing organic and particulate contaminants. Supercritical fluid, like SCC, is characterized by physical and thermal properties that are between those of the pure liquid and gas phases. The fluid density is a function of the temperature and pressure. Its solvating power can be adjusted by changing the pressure or temperature, or adding a secondary solvent such as alcohol or water. Unlike a regular organic solvent, SCC has higher diffusivities, lower viscosity, and lower surface tension. It readily penetrates porous and fibrous solids and can reach hard-to-reach surfaces of the parts with complex geometry. Importantly, the CO2 solvent does not leave any residue. The results using this new cleaning device demonstrated that both supercritical CO2 with 5% water as a co-solvent can achieve cleanliness levels of 0.01 mg/cm2 or less for contaminants of a wide range of hydrophobicities. Experiments under the same conditions using compressed Martian air mix, which consists of 95% CO2, produced similar cleaning effectiveness on the hydrophobic compounds. The main components of the SCC cleaning system are a high-pressure cleaning vessel, a boil-off vessel located downstream from the cleaning vessel, a syringe-type high-pressure pump, a heat exchanger, and a back pressure regulator (BPR). After soaking the parts to be cleaned in the clean vessel for a period, the CO2 with contaminants is flushed out of the cleaning vessel using fresh CO2 in a first-in-first-out (FIFO) method. The contaminants are either precipitating out in the boil-off container or being trapped in a filter subsystem. The parts to be cleaned are secured in a basket inside and can be rotated up to 1,400 rpm by a magnetic drive. The fluid flows within the vessel generate tangential forces on the parts surfaces, enhancing the cleaning effectiveness and shortening the soaking time. During the FIFO flushing, the pump subsystem pushes fresh CO2 into the cleaning vessel at a constant flow rate between 0.01 and 200 mL/min, while the BPR regulates the pressure in the cleaning vessel to within 0.1 bar by controlling the needle position in an outlet valve. The fresh CO2 gas flows through the heat exchanger at a given temperature before entering the cleaning vessel. A platinum resistance thermometer (PRT) reads the cleaning vessel interior temperature that can be controlled to within 0.1 K. As a result, cleaning vessel temperature remains constant during the FIFO flushing. There is no change in solvent power during FIFO flushing since both temperature and pressure inside the cleaning vessel remain unchanged, thus minimizing contaminants left behind. During decompression, both temperature and pressure are strictly controlled to prevent bubbles from generating in the cleaning vessel that could stir up the contaminants that sank to the bottom by gravity.

Lin, Ying↗
NASA NTRS1991

Thermal control surfaces experiment flight system performance

The Thermal Control Surfaces Experiment (TCSE) is the most complex system, other than the LDEF, retrieved after long term space exposure. The TCSE is a microcosm of complex electro-optical payloads being developed and flow by NASA and the DoD including SDI. The objective of TCSE was to determine the effects of the near-Earth orbital environment and the LDEF induced environment on spacecraft thermal control surfaces. The TCSE was a comprehensive experiment that combined in-space measurements with extensive post flight analyses of thermal control surfaces to determine the effects of exposure to the low earth orbit space environment. The TCSE was the first space experiment to measure the optical properties of thermal control surfaces the way they are routinely measured in a lab. The performance of the TCSE confirms that low cost, complex experiment packages can be developed that perform well in space.

Wilkes, Donald R.↗