Frozen Surfaces Research Articles

Subsurface Science and Search for Life in Ocean Worlds

Several worlds in our solar system are thought to hold oceans of liquid water beneath their frozen surfaces. These subsurface ice and ocean environments are promising targets in the search for life beyond Earth, but they also present significant new technical challenges to planetary exploration. With a focus on Jupiter’s moon Europa, here we (1) identify major benefits and challenges to subsurface ocean world science, (2) provide a multidisciplinary survey of relevant sample handling and life detection technologies, and (3) integrate those perspectives into the Subsurface Science and Search for Life in Ocean Worlds (SSSLOW) concept payload. We discuss scientific goals across three complementary categories: (1) search for life, (2) assess habitability, and (3) investigate geological processes. Major mission challenges considered include submerged operation in high-pressure environments, the need to sample fluids with a range of possible chemical conditions, and detection of biosignatures at low concentrations. The SSSLOW addresses these issues by tightly integrated instrumentation and sample handling systems to enable sequential, complementary measurements while prioritizing preservation of sample context. In this work, we leverage techniques and technologies across several fields to demonstrate a path toward future subsurface exploration and life detection in ice and ocean worlds.

Сады в «Трилистниках» И. Анненского (к вопросу о «вещественном» и символическом значении образа)

The development of garden space at Annensky contributes to an understanding of the individual symbolism of the poet and the principles of organizing semantic unity of the “Trilistniks” (trefoils). In the first trilistniks, the subject occupies an ambivalent position of attraction and repulsion in relation to the garden space (flowers, birds, earth). The intensity of color and smell, as well as the principle of contrast, oxymoron, are important in the description. The garden refers to biblical mythology (“Trefoil of temptation”). Nature is renewed, and man cannot get rid of the burden of the “evil” past and the idea of inevitability of death (“Sentimental trefoil”). Observing the phenomenon of light and shade in the garden, the lyrical “I” thinks about the existence of the world simultaneously outside and inside a man (“Lunar trefoil”). The garden in the “Trefoil of doomness” dedicated to the perception of time is a closed space, “the door is clogged there.” Gardens are gradually growing dim, become flatter, empty and move inside the consciousness of a lyrical subject (sleep, nonsense, fiction). The flowers on the window, the dead garden and the sky are perceived as solid, frozen surfaces (“Ghostlike trefoil”). The image of the garden takes on fantastic features: the old manor is placed in the space of a fairy tale (“Trefoil from the old notebook”), shadows in the garden turn into ghosts of the past and are condensed (“Spring trefoil”). “Trefoil of the loneliness,” the last in the series, is dedicated to the issue of alienation of a modern man from natural world and people, the bright image of the garden (lilacs, sun, bees) is located outside the personal space of the “I.”

Wide Skis As a Potential Knee Injury Risk Factor in Alpine Skiing

Alpine skis with wider waist widths have recently become more popular. With such skis, the contact point of the ground reaction force during ski turns is displaced more medially from beneath the sole of the outer ski, which may present an increased risk of injury. The aim of this study was to investigate knee joint kinetics, kinematics, and lower limb muscle activation as a function of changes of the ski waist width in a laboratory setting. A custom skiing simulator was constructed to enable simulation of different ski waist widths in a quasi-static ski turn position. An optical system was used for capturing knee joint kinematics of the outer leg, whereas a force plate was used to determine the ground reaction force vector. The combination of both systems enabled values for external torques acting on the knee joint to be calculated, whereas electromyographic measurements enabled an analysis of knee flexor muscle activation. With respect to the outer ski, the knee joint external torques were independent of ski waist width, whereas knee joint external rotation and biceps femoris activation increased significantly with the increase of the ski waist width. Skier muscle and kinematics adaptation most probably took place to diminish the external knee joint torque changes when the waist width of the ski was increased. The laboratory results suggest that using skis with large waist widths on hard, frozen surfaces may change the load of knee joint surfaces. However, future research is needed to clarify if this may result in the increased risk of knee injury.

Accelerated Springtime Melt of Snow on Tundra Downwind from Northern Alaska River Systems Resulting from Niveo-aeolian Deposition Events

It is well known that light-absorbing particulate matter (PM) enhances absorption of sunlight when deposited on ice and snow. Such increased absorption is due to a reduction in surface albedo, resulting in accelerated melt of frozen surfaces. In isolation, earlier melt enhances Arctic warming since dark surfaces underlying snow and ice are exposed and absorb additional solar energy. Here, we combine various observational tools to demonstrate that aeolian deposition of PM along fluvial features on the North Slope of Alaska resulted in a notable reduction of surface albedo in the spring of 2016, from values typical for snow (~0.8) to around 0.35 on average. This reduction resulted in accelerated snow and ice melt by up to three weeks compared to unaffected areas. This phenomenon was observed to some degree in 12 other years dating back to 2003. Deposition generally was found to occur near particular sections of the rivers, with several areas affected by events in multiple years. In all years, the deposition is attributed to high wind events. The extreme case in 2016 is linked to unusually strong and extraordinarily persistent winds during April. The deposited material is thought to be the natural sediment carried by the rivers, resulting in a seasonally replenished source of PM. These findings indicate a previously unreported impact of both fluvial and atmospheric processes on the seasonal melt of northern Alaska rivers.

Quantitative Analysis of the Process of Cooling a Coolant Using Developed Frozen Surfaces

The problem of cooling a liquid system by introducing frozen spheres into it can be formulated within the boundary value problem for the heat equation. The solution of this problem in analytical form for real values of the process parameters is used as a basis for the numerical simulation of the process of cooling a liquid system.

Small cryotherapy devices for the treatment of skin warts

Study purpose: Effectiveness of cryotherapy on skin wart models.Materials and methods: Two small cryotherapy devices, Wartner and Wortie, were administered for 10″–60″ on tomatoes and potatoes used as skin wart models. Frozen surface and depth were evaluated by standardized photography and computer analysis. Tissue temperature at depths of 0.1–10 mm was assessed by an electronic thermometer during treatment.Results: Cryotherapy induced a transient freezing of the tomato surface. The devices produced similar tomato tissue temperature reduction at all depths examined. At 5 mm, Wortie induced lower tissue temperatures than Wartner. Both devices induced potato tissue destruction to a depth of 0.5–1.2 mm at 40″ and 50″. Wartner induced a maximum destruction at 40″, Wortie led to a partially linear destruction depth with freezing time. The devices produced similar reduction of potato tissue temperature at all depths tested. Wartner induced more rapidly lower temperatures (1.5 mm, 10″, p = .001). Wortie induced lower tissue temperatures with time (0.1 mm, 50″, p = .025; 60″, p = .039; 5 mm, 60″, p = .05). None of the devices reached the lethal temperature of −22 °C.Conclusions: Both cryotherapy devices produced sufficient tissue damage, at least in the potatoes, to a depth of 0.5–1.2 mm when applied for 40″ (commercially proposed time).

Desorption from methanol ice induced by electrons from solar wind or magnetospheres

This work analyzes the physico-chemical effects due to electron irradiation, as e.g. caused by the solar wind, on pure methanol (CH3OH) ice. Methanol has been detected in gas and condensed phases in several astrophysical environments, such as comets, asteroids, toward star forming regions and molecular clouds. In some of these environments, methanol is the most abundant specie after water ice. The interaction of ionizing agents with methanol ice induces the production of ionized species, leading to the formation of new compounds. In this work, pure methanol ice (at 142K) was irradiated, in ultra-high vacuum regime, with 800eV electrons, thus simulating the wind in frozen surfaces. The desorbed ions were analyzed using time-of-flight mass spectrometry. The results show the formation of protonated species, such as (CH3OH)H+, H2COH+, C2H3+ and HCO+. Absolute desorption yields were determined and compared with results available in the literature from similar experiments. The ionic desorption rate is an important parameter in surface chemistry. It is often approximated in chemical evolution models of astrophysical environments, due to the lack of experimental data.

Impact on soil compaction of driving agricultural machinery over ground frozen near the surface

Abstract The compaction of arable soils caused by driving over them with agricultural machinery poses a serious problem in numerous agricultural regions across temperate climate zones. The risk of compaction is particularly high in early spring or late autumn when soils are wet. This is why driving over soils frozen near the surface is recommended in some cases in temperate climate zones to prevent soil compaction. However, no findings have been available about the thickness of frozen soil required to effectively prevent compaction when the soil is driven over. In one experiment, soil physical measurements were carried out on the topsoil after a single pass with a tractor (4100 kg wheel load, 80 kPa inflation pressure) over an unfrozen variant, a variant with 2–3 cm frost covering and a variant with 5–7 cm frost covering, with comparisons made with a control variant that had not been driven over. Driving over the unfrozen variant led to a significant compaction of the whole of the topsoil. By contrast, the frozen surfaces were able to significantly buffer the compaction. No appreciable differences were detected between the two depths of frost penetration. A depth of frost penetration of as little as 2–3 cm was therefore sufficient to reduce the risk of compaction with a wheel load of approximately 4000 kg and appropriately adjusted inflation pressure.

A modified cardioid model for Processing multiangular radiometric observations

L-band spaceborne microwave radiometers are becoming able to provide estimates of surface soil moisture, on both spatial and temporal scales compatible with applications to meteorology and hydrology. The basic rationale for retrieving soil moisture from radiometric measurements is the assumption that the surface layer can be modeled as a dielectric medium. Its dielectric constant then depends on several physical parameters, including soil moisture; emissivities for various incidence angles are computed using Fresnel's formulas. Many controlled field experiments have demonstrated the validity of this approach. Scenes exist still (e.g., ice-covered or frozen surfaces, barren areas) where surface soil moisture is not a relevant concept. For such scenes, information should, however, be available on the complex dielectric constant itself. This paper shows that the dielectric constant cannot be fully retrieved from single-frequency multiangular data; it describes, however, a methodology that aims at retrieving in an optimized way the available information.

Sublimation and aeolian sand movement from a frozen surface: experimental results from Presqu'ile beach, Ontario

Recent aeolian literature has indicated that sand movement can and does take place on frozen surfaces. The winter aeolian process is influenced by the pore ice which binds the sand grains together and increases the surface resistance to wind action. Sublimation of the frozen moisture provides loose grains of sand which subsequently can be entrained by the wind. Field experiments carried out on the Presqu'ile Beach, Ontario in the 1992–1993 winter provide some data on variables which affect sand loss from frozen surfaces because of sublimation. Sand moisture content determines the resistivity of the surface to sublimation-induced sand loss: frozen surfaces with higher moisture contents experience less sand loss. The existing literature has indicated that temperature plays an important role in the occurrence of sublimation: higher temperatures (i.e., temperatures which are closer to 0°C) result in higher rates of sublimation. However, the Presqu'ile experiments show that wind speed is more strongly correlated with sublimation-induced particle loss than temperature or relative humidity. Higher wind speeds allow sand from the surface and sublimation-produced water vapour to be removed from the area, thus providing an incentive for further sublimation and sand loss to take place. Information on the variables which affect sublimation-induced sand loss from frozen surfaces can be used to increase understanding of the processes involved in sand movement on frozen surfaces under subzero temperatures.

Ultrastructural findings on the skeletal muscles of pigs following ultrarapid chilling in the initial phase of meat maturation

The purpose of this study was to show the structural alterations in the short-term frozen surface musculature of slaughtered pigs followed ultrarapid chilling methods. In muscles with normal glycolysis the short-term freezing of the musculature following ultrarapid chilling within 3 h 45 min post mortem led to cold shortening and in some areas to considerable changes in the transverse striation. The interstitial and interfibrillar spaces revealed severe oedema. The organelles showed, almost without exception, extreme vacuolar alterations and the cell membranes appeared fragmented. The non-frozen musculature of the more slowly chilled control group revealed similar changes but of a minor or less serious nature. In the muscle samples with accelerated glycolytic rates only minor differences were observed between the ultrarapidly chilled and the control musculature. Final evaluation of the effect of these chilling methods can only take place after studying the influence of the ultrastructural changes on the water binding capacity and tenderness of the musculature.

Relative humidity predictor equations based on environmental factors

relative humidity frequency distributions from 43 eastern U.S. locations are examined to derive empirical predictive relationships for the upper end of the scale, as a function of local environmental conditions. Such predictions are needed in order to estimate the fraction of time that certain surfaces may be wet from condensation and thus more susceptible to atmospheric corrosion. For example, SO 2 is known to deposit more readily on wet surfaces. The additional constraint of ambient temperature above freezing is imposed, since both SO 2 deposition and corrosion are expected to be minimal on frozen surfaces. Factors that influence the frequency of high relative humidity (>80%) in the eastern U.S. were found to include degree of urbanization, latitude, and location near large bodies of water and near airports.

Water on Mars

It appears certain now that water exists on the surface of Mars both as ice and as liquid. A recent report by S . H. Zisk and P. J. Mouginis‐Mark indicates that liquid water exists in Mars' southern hemisphere at the area of Solis Lacus (Lake of the Sun). Interestingly enough, the results were obtained from radar data from earth‐based stations rather than from Viking spacecraft. The reason for this is that data from the Viking orbiters showed a rough, evidently solid, frozen surface. Images from the Viking spacecraft were obtained during the Martian winter, but the earth‐based radar measurements were obtained in the Martian summer.

Martian climatic change: A magnetic trigger?

A new mechanism for climatic change on Mars involving interactions between the atmosphere and a hypothesized ancient planetary magnetic field is suggested and discussed. An early dynamo for Mars is not inconsistent with either current data on the martian interior, models of planet origin, or dynamo theory. The Jacobs/Busse scaling law suggests a martian dynamo field would have effectively shielded the atmosphere from the solar wind. Cooling and/or solidification of the core would cause dynamo extinction and expose the martian atmosphere to the full solar and galactic particle flux. These events may have triggered atmospheric cooling and the present martian frozen surface; as suggested by: (1) climatic records of the earth, and (2) current models of nucleation and other relevant atmospheric processes.

The Cold Stub: A Simple Stage For the Direct Observation of Frozen Samples in the Scanning Electron Microscope

Cold block devices have been used in the scanning electron microscope to permit the viewing of frozen samples. These have the advantage of simplicity in that feedthroughs for liquid nitrogen (LN) or temperature control may not be necessary. Previous cold stages for the SEM have either been cumbersome and expensive or in some way restrict the use of the microscope for general purposes. Previous cold sinks designed by the authors, like other common cold stages, require a period of temperature adjustment so that contamination introduced to the sample surface during the loading phase of the SEM sublimes, exposing the underlying frozen surface. The present device carries the simplification steps somewhat further.

The Discharge in the Closed River with the whole Frozen Surface

The Discharge in the Closed River with the whole Frozen Surface

宇都宮の氷柱

宇都宮の氷柱