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DOE OSTI2022

Anti-Icing Coatings using Ionomer Film Layer Structuring

This research effort examined the application of Nafion polymers in alcohol solvents as an anti-ice surface coating, as a mixture with hydrophilic polymers and freezing point depressant salt systems. Co-soluble systems of Nafion, polymer and salt were applied using dip coating methods to create smooth films for frost observation over a Peltier plate thermal system in ambient laboratory conditions. Cryo-DSC was applied to examine freezing events of the Nafion-surfactant mixtures, but the sensitivity of the measurement was insufficient to determine frost behavior. Collaborations with the Fog Chamber at Sandia-Albuquerque, and in environmental SAXS measurements with CINT-LANL were requested but were not able to be performed under the research duration. Since experimental characterization of these factors is difficult to achieve directly, computational modeling was used to guide the scientific basis for property improvement. Computational modeling was performed to improve understanding of the dynamic association between ionomer side groups and added molecules and deicing salts. The polyacrylic acid in water system was identified at the start of the project as a relevant system for exploring the effect of varying counterions on the properties of fully deprotonated polyacrylic acid (PAA) in the presence of water. Simulations were modeled with four different counterions, two monovalent counterions (K+ and Na+) and two divalent counterions (Ca2+ and Mg2+). The wt% of PAA in these systems was varied from ~10 to 80 wt% PAA for temperatures from 250K to 400K. In the second set of simulations, the interpenetration of water into a dry PAA film was studied for Na+ or Ca2+ counterions for temperatures between 300K and 400K. The result of this project is a sprayable Nafion film composite which resists ice nucleation at -20 °C for periods of greater than three hours. It is composed of Nafion polymer, hydrophilic polyethylene oxide polymer and CaCl2 anti-ice crosslinker. Durability and field performance properties remain to be determined.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2021

The Portable Ice Nucleation Experiment (PINE): a new online instrument for laboratory studies and automated long-term field observations of ice-nucleating particles

Atmospheric ice-nucleating particles (INPs) play an important role in determining the phase of clouds, which affects their albedo and lifetime. A lack of data on the spatial and temporal variation of INPs around the globe limits our predictive capacity and understanding of clouds containing ice. Automated instrumentation that can robustly measure INP concentrations across the full range of tropospheric temperatures is needed in order to address this knowledge gap. In this study, we demonstrate the functionality and capacity of the new Portable Ice Nucleation Experiment (PINE) to study ice nucleation processes and to measure INP concentrations under conditions pertinent for mixed-phase clouds, with temperatures from about -10 to about -40°C. PINE is a cloud expansion chamber which avoids frost formation on the cold walls and thereby omits frost fragmentation and related background ice signals during the operation. The development, working principle and treatment of data for the PINE instrument is discussed in detail. We present laboratory-based tests where PINE measurements were compared with those from the established AIDA (Aerosol Interaction and Dynamics in the Atmosphere) cloud chamber. Within experimental uncertainties, PINE agreed with AIDA for homogeneous freezing of pure water droplets and the immersion freezing activity of mineral aerosols. Results from a first field campaign conducted at the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) observatory in Oklahoma, USA, from 1 October to 14 November 2019 with the latest PINE design (a commercially available PINE chamber) are also shown, demonstrating PINE's ability to make automated field measurements of INP concentrations at a time resolution of about 8 min with continuous temperature scans for INP measurements between -10 and -30°C. During this field campaign, PINE was continuously operated for 45 d in a fully automated and semi-autonomous way, demonstrating the capability of this new instrument to also be used for longer-term field measurements and INP monitoring activities in observatories.

54 ENVIRONMENTAL SCIENCES↗

NASA NTRS1971

The long winter model of Martian biology - A speculation.

A temporal microenvironment model is proposed for Martian biology that is based on an estimated mean thickness of nearly 1 km of frost in the Martian north polar cap summer remnant. If vaporized, this frost could yield not only 1 kg per sq cm of atmosphere, but also higher global temperatures through the greenhouse effect and a greatly increased likelihood of liquid water. Vaporization of such cap remnants may occur twice each equinoctial precession, and Martian organisms may now be in cryptobiotic repose awaiting the end of the long precessional winter. The Viking biology experiments might test this hypothesis.

Sagan, C.↗

NASA NTRS1972

Infrared thermal mapping experiment - The Viking Mars Orbiter.

The Mars infrared thermal mapper (IRTM) will be carried on the scan platform of the orbiter of the Viking 1975 mission. The IRTM is a multichannel radiometer with several detectors in each of six spectral regions. The spectral channels are selected to be sensitive to surface emissivity variations and provide good temperature resolution over the entire range of Martian temperatures. These observations will allow determination of the surface kinetic temperature and thermal balance, and by coverage of the dark hemisphere, a search for regions with anomalous cooling can be made. Observations of ground frosts or clouds will help to determine their composition, and in the case of extensive H2O frosts, will allow the local water vapor pressure to be estimated.

Kieffer, H. H.↗

NASA NTRS1973

Mariner 9 observations of the surface of Mars in the north polar region

The recession rate of the north polar cap, as monitored by Mariner 9, was not significantly different than has been observed from earth in the past. Thus, the dynamic planet-wide dust storm does not seem to have had a noticeable effect on the thickeness of the CO2 deposit which developed during the standard mission. The dominant role of local topography in controlling the configuration of the retreating cap is confirmed. At narrow-angle resolution the retreating frost has high-lighted topographic detail that may represent Martian polar eolian deposits. At wide angle resolution the topography of the smooth plains, rugged etch pitted terrain, and complex central polar deposits is emphasized by the frost.

Soderblom, L. A.↗

NASA NTRS1973

Mars - The intermediate between earth and moon

The present work represents a summary of the state of our knowledge concerning the chief physical characteristics of Mars as deduced from existing observational and theoretical evidence. Two main geological provinces are distinguished on Mars: areas of rough terrain and dense cratering, and smooth areas comparable to lunar maria. A thermal model for the Martian poles which takes into account convective transport would indicate that the CO2 frost over the north pole is not permanent, lasting about 420 days with the water frost lasting the remaining 267 days of the Martian year. The meandering appearance of Martian rift valleys are cracks probably produced, as also in the case of lunar rilles, by stresses, perhaps in solidifying lava of impact origin, and not by erosional river beds. Data indicate a strong absorption in the thin Martian atmosphere. The atmospheric blue and violet cap around a Martian pole in winter is interpreted as a 'blue clearing' of the atmosphere increasing transparency so that surface detail of higher albedo shines through in the blue.

Opik, E. J.↗

NASA NTRS1974

Some economic benefits of a synchronous earth observatory satellite

An analysis was made of the economic benefits which might be derived from reduced forecasting errors made possible by data obtained from a synchronous satellite system which can collect earth observation and meteorological data continuously and on demand. User costs directly associated with achieving benefits are included. In the analysis, benefits were evaluated which might be obtained as a result of improved thunderstorm forecasting, frost warning, and grain harvest forecasting capabilities. The anticipated system capabilities were used to arrive at realistic estimates of system performance on which to base the benefit analysis. Emphasis was placed on the benefits which result from system forecasting accuracies. Benefits from improved thunderstorm forecasts are indicated for the construction, air transportation, and agricultural industries. The effects of improved frost warning capability on the citrus crop are determined. The benefits from improved grain forecasting capability are evaluated in terms of both U.S. benefits resulting from domestic grain distribution and U.S. benefits from international grain distribution.

Battacharyya, R. K.↗

NASA NTRS1975

Thermal conductivity of comets

The thermal conductivity of two comet models is calculated. Both models assume the comets to be heterogeneous in composition. One model considers the comet to have a nucleus of water-ice mixed with basaltic and meteoritic material in the form of dust and agglomerated particles surrounded by a layer of water-frost. The second model assumes the frost and water-ice layers have sublimated, leaving a porous structure to some depth composed of solid basaltic and meteoritic material with residual gases. K values are calculated as a function of depth, density, temperature and porosity.

Kumar, G. N.↗

NASA NTRS1976

New upper limits for atmospheric constituents on Io

A spectrum of Io from 0.86 to 2.7 microns with a resolution of 3.36 per cm and a signal to rms noise ratio of 120 is presented. No absorptions due to any atmospheric constituents on Io could be found in the spectrum. Upper limits of 0.12 cm-atm for NH3, 0.12 cm-atm for CH4, 0.4 cm-atm for N2O, and 24 cm-atm for H2S were determined. Laboratory spectra of ammonia frosts as a function of temperature were compared with the spectrum of Io and showed this frost not to be present at the surface of Io. A search for possible resonance lines of carbon, silicon, and sulfur, as well as the 1.08-micron line of helium, proved negative. Upper emission limits of 60, 18, 27, and 60 kilorayleighs, respectively, were established for these lines.

Fink, U.↗

NASA NTRS1976

Laboratory reflection spectra for the determination of chemical composition of ice bodies

The visible (0.3 to 1.03 microns) spectral reflectances of N2O, NH3, H2S, and NH4HS frosts and mixtures of these frosts as well as their UV-irradiated products have been measured. These spectra are compared with the spectra of the Galilean satellites of Jupiter, Saturn's rings, and Saturn's satellites to place limits on their surface compositions.

Lebofsky, L. A.↗

NASA NTRS1977

Identification of a new class of satellites in the outer solar system

From near-infrared photometry (JHKL) of small bodies in the outer solar system a previously unrecognized class of planetary satellites is identified which may have surfaces mostly free of frosts of water, methane, or ammonia. These bodies - including two satellites of Uranus (Titania and Oberon), and one each of Saturn (Hyperion) and Neptune (Triton) - have surfaces characterized by neutral reflectance between J and H (1.25 and 1.60 microns) and rapidly decreasing reflectance at K (2.2 microns) and L (3.5 microns). It is pointed out that the 15 solid bodies in the outer solar system that have been satisfactorily observed (excluding the asteroids) fall into six classes according to spectral reflectance. The presence of water frost or ice on the surface of Enceladus is established.

Cruikshank, D. P.↗

NASA NTRS1978

A rocket observation of the far-ultraviolet spectrum of Saturn

Far-ultraviolet (1160-1750 A) spectra of the Saturnian disk and the ring system have been obtained by using a very sensitive rocket-borne spectrograph with a microchannel plate detector. The use of two apertures of different diameter in the telescope focal plane permitted the separation of the contribution of the planetary disk from that of the rings. H I lambda 1216 was the only atomic spectral line emission detected in the planet and the rings. A weak signal from the disk between 1300 A and 1500 A was observed. Geometric disk albedos, averaged over 50 A, were determined from 1500 A to 1700 A. Measurements of the ring reflectivity longward of 1650 A are compatible with H2O frost but not NH3 frost.

Weiser, H.↗

NASA NTRS1978

Economic consequences of improved temperature forecasts: An experiment with the Florida citrus growers (an update of control group results)

The economic experiment, the results obtained to date and the work which still remains to be done are summarized. Specifically, the experiment design is described in detail as are the developed data collection methodology and procedures, sampling plan, data reduction techniques, cost and loss models, establishment of frost severity measures, data obtained from citrus growers, National Weather Service and Federal Crop Insurance Corp. Resulting protection costs and crop losses for the control group sample, extrapolation of results of control group to the Florida citrus industry and the method for normalization of these results to a normal or average frost season so that results may be compared with anticipated similar results from test group measurements are discussed.

Braen, C.↗

NASA NTRS1979

Geomorphic processes on the North Slope of Alaska

Three physiographic provinces comprise the North Slope of Alaska: the Arctic Mountains, the Arctic Foothills and the Arctic Coastal Plain Provinces. The features and processes in the Arctic Coastal Plain, a zone of continuous permafrost, are stressed in this paper. The evidence for and mechanisms of the geomorphic cycle are discussed starting with frost cracks. Frost cracks may form polygonal ground which leads to low-centered ice wedge polygons in areas having ice-rich permafrost. As the low-centered ice wedge polygons enlarge due to thermal erosion they may evolve into thaw lakes which are largely oriented in a northwest-southeast direction on the Arctic Coastal Plain. Eventual drainage of a deep lake may result in a closed-system pingo. Evidence of the various stages of the geomorphic cycle is ubiquitous on the Alaskan Arctic Coastal Plain and indicates the ice content of the permafrost in some areas.

Hall, D. K.↗

NASA NTRS1979

Surface composition of Pluto

Broadband (J, H, K and L) and narrowband (1.5- to 3.7-micron) infrared photometry of Pluto has been conducted in order to check previous ambiguous observations of methane frost on the planet's surface. In detail, the match between a laboratory spectrum of methane frost and the observed spectrum of Pluto is not good. Nevertheless, the photometric observations suggest the presence of methane in some form.

Lebofsky, L. A.↗

NASA NTRS1979

Io's surface and environs - A magmatic-volatile model

A model is proposed to account for the observed properties of Io. The crust is probably siliceous, but the outermost visible surface is composed primarily of several allotropes of elemental sulfur, plus frosts of SO2, H2S, and S2O. The 4-micron feature in Io's IR reflectance is identified as the (nu 1 + nu 3) band of SO2 frost. A possible source of the S is dissociation of iron sulfide brought up from the core by mantle convection. The SO2 is produced in the volcanoes, and the H2S by interaction of magnetospheric protons with the surface S. Delayed luminescence from S2O could cause the posteclipse brightening. The orbital torus is sustained by evaporation from molten ejecta from the volcanoes. Several additional diagnostic absorption bands and two additional minor torus species are predicted by this model.

Hapke, B.↗

NASA NTRS1980

The Galilean satellites - New near-infrared spectral reflectance measurements /0.65-2.5 microns/ and a 0.325-5 micron summary

New near-infrared (0.65-2.5 microns) reflectance spectra of the Galilean satellites are presented. These spectra more precisely define the water ice absorption features previously identified on Europa, Ganymede, and Callisto at 1.55 and 2.0 microns. In addition, previously unreported spectral features due to water ice are seen at 1.25, 1.06, 0.90, and 0.81 microns on Europa, and at 1.25, 1.04, and possibly 0.71 microns on Ganymede. Unreported absorption features in Callisto's spectrum occur at 1.2 microns, probably due to H2O, and a weak, broad band extending from 0.75 to 0.95 microns due possibly to other minerals. The spectrum of Io has only weak absorption features at 1.15 microns and between 0.8 and 1.0 microns. No water absorptions are positively identified in the Io spectra, indicating an upper limit of areal water frost coverage of 2% (leading and trailing sides). It is found for Callisto, Ganymede, and Europa that the water ice absorption features are due to free water and not to water bound or absorbed onto minerals. The areal coverage of water frost is approximately 100% on Europa (trailing side), approximately 65% on Ganymede (leading side), and 20-30% on Callisto (leading side). An upper limit of approximately 5% bound water (in addition to the 20-30% ice) may be present on Callisto, based on the strong 3-micron band seen by other investigators. A summary of spectra of the satellites from 0.325 to about 5 microns to aid in laboratory and interpretation studies is also presented.

Clark, R. N.↗

NASA NTRS1981

IO - Could SO2 condensation/sublimation cause the sometimes reported post-eclipse brightening

It is shown that each of the three quantifiable brightening characteristics (i.e., amplitude, time-scale /half-life/, and temporal variability) suggests that brightening of Io may be due to condensation and sublimation of SO2 frost. This is concentrated within a region that encompasses both the subsolar points at the time of entrance into and emergence from eclipse, and volcanic sources. Qualitatively and intuitively, an SO2 frost hypothesis is found to provide good possibilities for explaining any variations in Io's ability to brighten, which may occur on a time scale of years.

Fanale, F. P.↗