This paper analyzes the stabilizing effect of stone dust, granite dust, marble dust, and calcium lignosulphonate on construction materials and natural soils during road construction. The ultimate aim was to enhance the soil's engineering properties such that the pavement constructed could correctly withstand the load applied. To achieve this, every stabilizer was amalgamated with the soil at various percentages between 5 and 50%. Measurements were made of Atterberg limit tests, moisture content, and specific gravity. The research demonstrated that a diminution in optimal moisture content was seen, with an elevation in maximum dry density and California bearing ratio (CBR). Enhancements in the unconfined compressive strength were also identified. The outcomes determined that the untreated soil's CBR was 2.27% and in the case of soil with 45% additives, the CBR attained was 5.05%. When the soil was mixed with 50% additives, performance of 30.21%, 17.42%, and 12.82% was exhibited for (a) liquid limit, (b) plastic limit, and (c) plasticity index. Moreover, via the addition of presented stabilizers, the soil's mechanical properties were elevated appreciably.

Photovoltaic (PV) module soiling, i.e., the accumulation of soil deposits on the surface of a PV module, directly affects the amount of solar energy received by the PV cells in that module and has also been suggested as a mechanism that can give rise to additional heating, leading to significant power generation losses or even physical degradation, damage and lifetime reduction. Investigations of PV soiling are challenging and limited. We present results from an extensive outdoor experimental testing campaign of soiling, apply detailed characterisation techniques, and consider the resulting losses. Soil from sixty low-iron glass coupons was collected at various tilt angles over a study period of 12 months to capture monthly, seasonal and annual variations. The coupons were exposed to outdoor conditions to mimic the upper surface of PV modules. Transmittance measurements showed that the horizontal coupons experienced the highest degree of soiling. The horizontal wet-season, dry-season and full-year samples experienced a relative transmittance decrease of 62 %, 66 %, and 60 %, respectively, which corresponds to a predicted relative decrease of 62 %, 66 %, and 60 % in electrical power generation. An analysis of the soiling matter using an X-ray diffractometer and a scanning electron microscope showed the presence of particulate matter with diameters <10 mu m (PM10), which was the most prevalent in the studied region. The findings of this study lay the groundwork for research into soiling mitigation practices.

In 2022, our country will return to the Moon. This is a daunting task with many challenges and dangers. One of them, so far the least studied and most obscure, is the subject of this article, prepared using the materials of the report Exploration of the Moon and Planets with the Help of Automatic Spacecraft: A Prelude to the Exploration of the Moon by Man (it was heard at a scientific session of the General Meeting of RAS members on April 21, 2021). The surface of the Moon, like most atmosphereless bodies, is covered with a layer of dust: a fine fraction of regolith, crushed over hundreds of millions of years of being on the surface of the planet. Under the influence of external factors-both natural and anthropogenic-dust particles can rise from the surface, levitate under the influence of electrostatic forces, and settle on spacecraft. The experience of the six American Apollo manned missions showed that lunar dust microparticles affected the service systems of the lander, deposited on the astronauts' suits, got into the air recirculation systems of the sealed lander and, as a result, influenced the health of the astronauts. Considering the size of such particles, which can be tens or hundreds of nanometers, it has become clear that the toxicity of moondust is one of the most serious problems in the study of the Moon with human participation. This conclusion was made at the end of the Apollo program. The factor of lunar dust during manned missions to the Moon is discussed, and methods for solving this problem are outlined.

The surface of the Moon, like that of any airless body in the Solar System, constantly experiences micrometeorite bombardment as well as the influence of solar radiation, solar wind, and other factors of outer space. As a result of the impacts of high-velocity micrometeorites over billions of years, the lunar surface silicate basis crumbles, turning into particles with a wide size distribution. Considering the explosive nature of their origin, these particles are characterized by an extremely irregular shape with sharp edges or conglomerates sintered at high temperatures or almost spherical droplets. On the illuminated side of the Moon, solar radiation, especially the ultraviolet part of its spectrum, and solar wind streams interact with the upper regolith layer, charging the regolith surface. The photoelectrons generated above the surface create, together with the charged regolith surface, a near-surface double layer. The electric field generated in this layer, as well as the particle charge fluctuations on the surface, create conditions under which electric forces may exceed the gravitational force and the van der Waals force of adhesion. As a result, micron- and submicron-sized regolith particles become capable of detaching from the surface and levitating above it. These dynamic processes cause the transport of dust particles above the lunar surface and the scattering of sunlight on these particles. Glows of this kind were observed over the lunar surface by television systems of American and Soviet landing vehicles in the early stages of lunar exploration. American astronauts who landed on the lunar surface during the Apollo program also discovered manifestations of lunar dust. It turns out that dust particles levitating over the regolith surface due to natural processes and those took off the surface due to anthropogenic factors cause many technological problems that compromise the performance of landing vehicles and their systems, hamper astronaut activity on the lunar surface, and are detrimental to their health. Based on the results of these missions, it is concluded that micron- and submicron-sized dust particles, levitating above the surface, pose a major, barely surmountable obstacle in further research and exploration of the Moon. Since then, studies of physical processes associated with the behavior of lunar dust, manifestations of its aggressive properties (toxicity), and ways to reduce the harmful effects of dust on engineering systems and on humans have become topical in theoretical and experimental research. In this review, the results of the past half century of studies on the behavior of dust particles serve as a basis to discuss the formation of the lunar regolith and the Moon's near-surface plasma-dust exosphere under the influence of outer space factors. The causes and conditions underling the behavior of dust particles are examined as well as implications of these processes, the influence of anthropogenic factors, and possible hazards to spacecraft and engineering systems during the implementation of the currently planned programs of lunar research and exploration. The main unsolved problems are listed in studying the behavior of the dust component of the lunar regolith; ways to address the problematic issues are discussed.

Physical conditions in the near-surface layer of the Moon are overviewed. This medium is formed in the course of the permanent micrometeoroid bombardment of the lunar regolith and due to the exposure of the regolith to solar radiation and high-energy charged particles of solar and galactic origin. During a considerable part of a lunar day (more than 20%), the Moon is passing through the Earth's magnetosphere, where the conditions strongly differ from those in the interplanetary space. The external effects on the lunar regolith form the plasma-dusty medium above the lunar surface, the so-called lunar exosphere, whose characteristic altitude may reach several tens of kilometers. Observations of the near-surface dusty exosphere were carried out with the TV cameras onboard the landers Surveyor 5, 6, and 7 (1967-1968) and with the astrophotometer of Lunokhod-2 (1973). Their results showed that the near-surface layer glows above the sunlit surface of the Moon. This was interpreted as the scattering of solar light by dust particles. Direct detection of particles on the lunar surface was made by the Lunar Ejects and Meteorite (LEAM) instrument deployed by the Apollo 17 astronauts. Recently, the investigations of dust particles were performed by the Lunar Atmosphere and Dust Environment Explorer (LADEE) instrument at an altitude of several tens of kilometers. These observations urged forward the development of theoretical models for the lunar exosphere formation, and these models are being continuously improved. However, to date, many issues related to the dynamics of dust and the near-surface electric fields remain unresolved. Further investigations of the lunar exosphere are planned to be performed onboard the Russian landers Luna-Glob and Luna-Resurs.