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This article explores the topic of cosmic dust and its significance in understanding the universe. Cosmic dust is found throughout our solar system and beyond, and it has posed challenges for astronomers in studying celestial objects. However, advancements in science and technology have allowed researchers to use cosmic dust as a valuable source of information about the composition and evolution of distant bodies in the universe. The article discusses the different types of cosmic dust, its role in phenomena such as interstellar reddening, and its potential to provide insights into the early stages of the universe and the origin of life on Earth. It also highlights recent space missions and laboratory simulations that have contributed to our understanding of cosmic dust. The collection of articles in this special issue of Philosophical Transactions of the Royal Society A focuses on specific aspects of cosmic dust research, including the detection and analysis of meteors and meteorites, in situ detection of dust particles in interplanetary space, and laboratory simulations of icy dust grains from subsurface ocean-bearing icy moons. [Extracted from the article]

Today's moon is vastly different from what it was 3 billion years ago. At that time, it was home to a collisional atmosphere formed through massive amounts of volcanism, releasing enough subsurface gas to sustain surface pressures of up to 1 kPa. Observations of our solar system have taught us that all dense atmospheres are host to clouds and aerosols, and we expect the Moon's to be no different. Knowing when, where, and under what conditions cloud particles form is important for understanding the evolution of the lunar atmosphere, how it reacted to temperature gradients, and how it cycled volatiles. To study this, I investigated the immersion freezing properties of three aerosols: JSC- 1A lunar simulant, which is similar in composition and properties to lunar sample #14163 returned by the Apollo 14 Mission; Exolith LMS- 1D Lunar Mare simulant, which simulates volcanic deposits on the Moon's surface; and Arizona Test Dust (ATD), a standard for Earth atmospheric studies. A Peltier thermoelectric cooler and droplet freezing array were used to isolate Millipore water droplets with aerosols cooled to temperatures as low as - 18 ° C. Aerosol type, aerosol concentration, and droplet size was varied across these experiments. Both lunar simulants were found to nucleate ice less frequently than ATD, with JSC- 1A nucleating more droplets than LMS- 1D, which exhibited freezing properties similar to pure water. The results indicate that water ice nucleation is possible but highly variable on lunar regolith aerosols, and cloud formation on volcanic dust may have been possible in the ancient lunar atmosphere. [ABSTRACT FROM AUTHOR]

The article discusses China's upcoming Chang'e-6 mission, which aims to retrieve samples from the Moon's South Pole–Aitken (SPA) Basin, the largest and oldest impact crater on the lunar far side. Topics include the mission's goal of dating the SPA impact event, potential geological insights from the retrieved samples, and the broader implications for understanding the Moon's formation and the "late heavy bombardment" hypothesis.

We investigate the comparative effect of impacts by trans-Neptunian Objects on the atmospheres of the moons Ganymede, Callisto, Europa, and Titan. We derive an analytic prescription for the 'stalling mass' (i.e. the atmosphere mass at which equilibrium between erosion and volatile delivery occurs), which is tested against a numerical model, demonstrating that the behaviour of the atmosphere matches the analytic prediction, albeit with stochastic events causing orders of magnitude variability. We find that bombardment, neglecting other effects, predicts atmosphere erosion on Ganymede, Callisto, and Europa leading to masses in quantitative agreement with the observed atmospheres. The predicted masses are relatively insensitive to the impactor size and velocity distributions, but sensitive to impactor density and volatile content. Crucially, we find that in this model the frequent arrival of 1–20 km-sized objects sets the quiescent atmosphere masses of the different moons, with atmospheres returning to these levels on ∼100 Myr time-scales at current bombardment levels, and larger impactors causing stochastic excursions to larger atmosphere masses. This quiescent level is higher on Titan than the Jovian moons due to the typically slower impact velocities, but to recreate Titan's massive current atmosphere an additional volatiles contribution is needed, which may be provided by impact-triggered outgassing. If so, the predicted mass is then dependent on the outgassing efficiency and the volatile mass contained in the crust, both of which are uncertain. This work highlights the role that impacts may have played in shaping the atmosphere evolution of outer Solar system moons, and the importance of stochastic effects. [ABSTRACT FROM AUTHOR]

China's Chang'e-6 mission aims to land in the South Pole-Aitken Basin (SPA), the Moon's largest and oldest impact crater, to collect rocks and soil samples. Scientists hope that these samples will provide insights into the timing and nature of the SPA impact, which is still a topic of debate. The samples may also shed light on the differences between the Moon's near side and far side, as well as the formation of the Moon itself. Chang'e-6 is part of China's successful lunar exploration program and is expected to share samples internationally. [Extracted from the article]

Global exosphere models of alkali gases surrounding Mercury and the Moon assume that the primary effect of the porous soil is to reduce the effective desorption rates. We demonstrate with a kinetic simulation that, following adsorption, the complicated structure of soils has two additional effects on the fate of previously released alkali atoms: (1) trapping of free atoms at lunar temperatures by microscopic shadows and inward diffusion, which becomes the primary sink mechanism, and (2) high‐energy barriers for thermal desorption compared to what would be retrieved from experiments on thin films or compacted pellets, especially when surface diffusion of adsorbates is considered. Lunar soils retain one fifth to two thirds of recycled adsorbates, depending on the assumed adsorbate mobility, photodesorption cross section, and soil thermal gradient. A transition from a retentive surface to full outgassing at T > 500 K will produce complex feedback mechanisms of alkali circulation at Mercury. Plain Language Summary: This paper seeks to understand physical processes that occur on mineral surfaces throughout the Solar System and which affect the atmospheres of Mercury and the Moon. When meteoroids and the solar wind impact the surface, they vaporize sodium and potassium atoms, some of which cannot escape the body's gravity and can populate the atmosphere with successive bounces until they are lost to space via ionization, react with the surface, or penetrate into the soil. We quantify the competition between evaporation and diffusion within the top 1 mm of the soil, which supports the atmosphere reservoir, by following test particle trajectories in soils simulated with a sphere packing code. The simulations provide empirically constrained insights about the longevity of these free atoms. These findings provide context for understanding observations from ground‐based telescopes, MESSENGER and LADEE observations, and laboratory experiments and pave the way for higher‐fidelity models of exospheres for these species. Key Points: We modeled processes occurring on very different timescales in the soil of Mercury and the MoonMicroscopic shadows trap up to half of the deposited sodium and potassium atoms at lunar temperaturesDesorption of previously trapped atoms at higher temperatures could induce additional feedback in Mercury sodium circulation models [ABSTRACT FROM AUTHOR]

Again; he proceeds, whatever may be said of the reason assigned by Dr. Halley for the dim light of the sun before his immersion; namely, the vapors in the moon's atmosphere, collected during the long night; yet it would seem to be very certain, that the temperature of the western edge, which is just then passing from night to day, must be decidedly lower than that of the eastern edge, which has been exposed to the sun's light for many days together. He expresses these laws in the following terms: - L aw I. On the near approach of the moon, a minute beam of light is, in some cases, bent into a physical curve, the direction of 232 CELEBRATION OF THE HUNDREDTH ANNIVERSARY OF THE APS which is concave toward the surface of the moon, in the region in which the beam escapes from her influence. I. If a minute beam from a star, which is about to he occulted, pass near to that region of the moon's limb at which the distortion outward may prevail, the rays of light will be more and more bent as in fig. 1, until the flexure arrives at its maximum, the moon's edge having advanced to M, or very near it. In other cases, or in the neighborhood of other portions of the moon's limb, a minute beam of light is sometimes bent into a physical curve, the direction of which is convex toward the surface of the moon, in the region in which the beam escapes from her influence. [Extracted from the article]

Lunar flyby or lunar gravity assist is a classical technique to change the energy and trajectory of space vehicle in space mission. In this paper, lunar flyby transfers between Sun--Earth/Moon libration point orbits with different energies are investigated in the Sun--Earth--Moon restricted four-body problem. Distinguished by behaviours before and after lunar flyby, classification of lunar flyby orbits is defined and studied. Research indicates that junction point of special regions of four types of lunar flyby orbits denotes the perilune of lunar flyby transfer between libration point orbits. Based on those special perilunes, retrograde and prograde lunar flyby transfers are discussed in detail, respectively. The mean energy level transition distribution is proposed and applied to analyse the influence of phase angle and eccentricity on lunar flyby transfers. The phase space is divided into normal and chaotic intervals based on the topology pattern of transfers. A continuation strategy of lunar flyby transfer in the bicircular model is presented. Numerical examples show that compared with the single-impulse transfers based on patched invariant manifolds, lunar flyby transfers are more energy efficient. Finally, lunar flyby transfers are further extended to the realistic models. [ABSTRACT FROM AUTHOR]

Large bodies, such as the Moon, that have remained relatively unaltered for long periods of time have the potential to preserve a record of organic chemical processes from early in the history of the Solar System. A record of volatiles and impactors may be preserved in buried lunar regolith layers that have been capped by protective lava flows. Of particular interest is the possible preservation of prebiotic organic materials delivered by ejected fragments of other bodies, including those originating from the surface of early Earth. Lava flow layers would shield the underlying regolith and any carbon-bearing materials within them from most of the effects of space weathering, but the encapsulated organic materials would still be subject to irradiation before they were buried by regolith formation and capped with lava. We have performed a study to simulate the effects of solar radiation on a variety of organic materials mixed with lunar and meteorite analog substrates. A fluence of ∼3 × 1013 protons cm−2 at 4-13 MeV, intended to be representative of solar energetic particles, has little detectable effect on low-molecular-weight (≤C30) hydrocarbon structures that can be used to indicate biological activity (biomarkers) or the high-molecular-weight hydrocarbon polymer poly(styrene-co-divinylbenzene), and has little apparent effect on a selection of amino acids (≤C9). Inevitably, more lengthy durations of exposure to solar energetic particles may have more deleterious effects, and rapid burial and encapsulation will always be more favorable to organic preservation. Our data indicate that biomarker compounds that may be used to infer biological activity on their parent planet can be relatively resistant to the effects of radiation and may have a high preservation potential in paleoregolith layers on the Moon. Key Words: Radiation-Moon-Regolith-Amino acids-Biomarkers. Astrobiology 16, 900-912. [ABSTRACT FROM AUTHOR]

The Lunar Dust Experiment (LDEX), aboard NASA’s Lunar Atmosphere and Dust Environment Explorer (LADEE) successfully mapped the dust density distribution over the lunar surface up to an altitude of ∼ 250 km. LDEX detected dust grains launched off the surface in ejecta plumes generated by impacts of cometary and asteroidal micrometeoroids striking the Moon. While on average LDEX detected particles at a rate of 1 min − 1 , periodically it measured bursts of particles at a rate exceeding the average value by up to two orders of magnitude. The timing and location of the most intense period of bursts is used here to independently determine the radiant for the Geminids meteoroid stream. The method is proposed to be of general interest to characterize meteoroid streams bombarding any of the airless bodies in the solar system using in-situ dust detectors. [ABSTRACT FROM AUTHOR]

The article discusses the significant evolution of lunar crustal formations in response to several space explorations and researches in astronomy. It provides a summary of lunar crustal formation models based on various investigations which illustrate how much are need to be learnt from the Moon. It also mentions how such studies indicates that understand of lunar differentiation offers more important contextual framework for observations from other rocky bodies in the solar system.

Lunar permanently shaded regions (PSRs) are unique solar-system environments. Their low temperatures (<100 K) facilitate cold trapping of volatile materials over timescales comparable to the lifetime of the solar system. While much has been learned about these regions from orbital spacecraft, important missing information includes the spatial and depth-dependent distribution of bulk hydrogen concentrations in and around PSRs. We present two complementary mission scenarios where orbital neutron spectroscopy will provide significantly improved understanding of lunar polar bulk hydrogen concentrations. In the first mission concept, a six-month orbital mission will measure bulk hydrogen concentrations with sensitivity better than 50 ppm and a spatial resolution of order 20 km over the entire lunar South Polar region (poleward of 80ºS). Spatial reconstruction analyses of the returned data will improve the final spatial resolution to better than 10 km. The presence and burial depth (<25 cm) of subsurface deposits will be quantified with latitude-dependent sensitivities ranging from 50 to 350 ppm. The second concept envisions a few, very low altitude (~5 km) flyovers of one or more PSRs to quantify the hydrogen concentrations and spatial heterogeneities with a hydrogen sensitivity less than 200 and spatial scale size of 5 km. Both concepts can be combined in a single mission where full-coverage polar measurements are made with a hydrogen spatial resolution of 20 km, and higher spatial resolution measurements are made for a few strategically selected PSRs at the end of the mission. [ABSTRACT FROM AUTHOR]

Abstract: With growing knowledge of the lunar surface environment from recent robotic missions, further assessment of human lunar infrastructures and operational aspects for surface exploration become possible. This is of particular interest for the integration of advanced mobility assets, where path planning, balanced energy provision and consumption as well as communication coverage grow in importance with the excursion distance. The existing modeling and simulation tools for the lunar surface environment have therefore been revisited and extended to incorporate aspects of mobile exploration. An extended analysis of the lunar topographic models from past and ongoing lunar orbital missions has resulted in the creation of a tool to calculate and visualize slope angles in selected lunar regions. This allows for the identification of traversable terrain with respect to the mobile system capabilities. In a next step, it is combined with the analysis of the solar illumination conditions throughout this terrain to inform system energy budgets in terms of electrical power availability and thermal control requirements. The combination of the traversability analysis together with a time distributed energy budget assessment then allows for a path planning and optimization for long range lunar surface mobility assets, including manned excursions as well as un-crewed relocation activities. The above mentioned tools are used for a conceptual analysis of the international lunar reference architecture, developed in the frame of the International Architecture Working Group (IAWG) of the International Space Exploration Coordination Group (ISECG). Its systems capabilities are evaluated together with the planned surface exploration range and paths in order to analyze feasibility of the architecture and to identify potential areas of optimization with respect to time-based and location-based integration of activities. [Copyright &y& Elsevier]

Abstract: The Cassini mission revealed two spectacular characteristics of Iapetus: (1) a geologically old and high equatorial ridge, which is unique in the Solar System and (2) a large flattening of 35km consistent with the equilibrium figure for a hydrostatic body rotating with a period of 16h, whereas the current spin period is 79.33 days. This study describes three-dimensional simulations of solid-state convection within an undifferentiated Iapetus. It investigates the implications for the evolution of the interior thermal structure and its spin rate and global shape using radially layered viscoelastic models. The role of the concentration in the short-lived radiogenic element [26Al], just after accretion is completed, is specifically addressed. The first result is to show that whatever the [26Al] value, convection occurs. As suggested by Castillo-Rogez et al. [Castillo-Rogez, J., Matson, D., Sotin, C., Johnson, T., Lunine, J., Thomas, P. [2007] Icarus, 190, 179–202], convection reduces the warming of the interior compared to the conductive evolution and therefore limits the conditions for despinning. In our calculations, two conceptual linear viscoelastic models are used. When considering a Maxwell rheology, the interior temperature (viscosity) never reaches a value high (low) enough to induce despinning. In order to promote dissipation at low temperature, a Burgers rheology, which includes an additional dissipation peak, is introduced. For favorable parameter values, this latter rheology leads to despinning. However, only models associated with large amounts of short-lived radiogenic elements lead to the observed flattening. This suggests that the accretion process needs to be completed shortly after the formation of CAIs (Calcium–Aluminum-rich Inclusions) (⩽4Myr). For [26Al] varying between 72 and 46ppb, the observed flattening is obtained only for a limited range of initial spin period, between 9.5 and 10.2h. For [26Al] ranging between 30 and 15ppb, initial spin rates smaller than 8.5h are required. For smaller values of [26Al], the body is too cold and viscous to acquire a significant flattening even if a rotation period close to the body disruption limit is considered. Even with a thin lithosphere during the early stage, our simulations show that Iapetus never reaches the equilibrium figure for a hydrostatic body due to the non-zero rigidity of the lithosphere. The 35km value of the flattening is the result of the partial relaxation of an ancient larger flattening ranging between 45 and 80km, depending on the evolution of the lithosphere thickness mainly controlled by the radiogenic content. A thin lithosphere is consistent with an early building of the equatorial ridge. The lithosphere thickening due to interior cooling can explain the preservation of the ridge throughout the remaining evolution of Iapetus. [Copyright &y& Elsevier]

The two isotopes of nitrogen, 14N and 15N. have relative abundances extremely variable among solar system reservoirs such as planets arid their atmospheres, primitive and differentiated meteorites. and comets. Expressed in the delta notation (δ15N = [[15N/14N]sample/[15N/14N]standard-1] × 1000, in parts per mil, or ‰ where the standard is atmospheric N having 15N/14N = 0.003676), δ15N ranges from -250‰ (the lower limit of lunar soil values) up to 1600‰ (measured in the meteorites benccubinites). The lunar surface constitutes a unique archive of the past corpuscular (solar and meteoritic) contributions to planetary surfaces. Nitrogen trapped in the lunar regolith presents a highly variable isotopic composition, which represents either secular variation of the solar wind composition although this possibility conflicts with the apparent isotope stability over time of other solar wind volatile elements, or more likely different contributions from solar corpuscular radiation and non-solar sources. In this ease. the solar nitrogen component is depleted by more than 24% in 15N. whereas non-solar, planetary sources (meteorites, micrometeorites, possibly comets) are enriched fri the heavy isotope of nitrogen by ≥10% on average. Variations in the nitrogen isotopic composition of lunar soils are explained by a secular change in the strength of the planetary flux. and a correlation between N isotopic compositions and surface exposure age tor different soils suggest that the planetary contribution to the inner solar system might have increased fri the last 0.4 Gy. The variability of the N isotope composition among solar system objects might be due to incomplete equilibration of nitrogen isotopes from different host phases of pre-solar origin. Alternatively, it could result from mixing between 15N-depleted protosolar nitrogen originally present in the gas and presolar solid (organic?) compounds enriched in 15N. [ABSTRACT FROM AUTHOR]

This paper reviews habitability conditions for a terrestrial planet from the point of view of geosciences. It addresses how interactions between the interior of a planet or a moon and its atmosphere and surface (including hydrosphere and biosphere) can affect habitability of the celestial body. It does not consider in detail the role of the central star but focusses more on surface conditions capable of sustaining life. We deal with fundamental issues of planetary habitability, i.e. the environmental conditions capable of sustaining life, and the above-mentioned interactions can affect the habitability of the celestial body. We address some hotly debated questions including: How do core and mantle affect the evolution and habitability of planets? What are the consequences of mantle overturn on the evolution of the interior and atmosphere? What is the role of the global carbon and water cycles? What influence do comet and asteroid impacts exert on the evolution of the planet? How does life interact with the evolution of the Earth's geosphere and atmosphere? How can knowledge of the solar system geophysics and habitability be applied to exoplanets? In addition, we address the identification of preserved life tracers in the context of the interaction of life with planetary evolution. [ABSTRACT FROM AUTHOR]

The article focuses on the varied features of moons. The moons (natural satellites) of the solar system are especially interesting in their incredible range of diversity. It is perhaps the variety of features among the moons that make them so interesting to study. The moons in the solar system are typically either rocky or a mixture of rock and ice. Most are airless, however, some of them have an atmosphere. Some are even volcanically active, with eruptions or fissure flows of molten rocky material or slushy ice. Some moons are very hot, while others are very cold--extreme conditions compared to Earth.

The article discusses the U.S. National Aeronautics and Space Administration's (NASA's) Lunar Atmosphere and Dust Environment Explorer (LADEE). Topics include the primary mission of LADEE, which includes learning more about the moon's atmosphere, LADEE's Lunar Dust Experiment (LDEX), and the benefits of characterizing the lunar atmosphere and its dust, such as helping astronomers interpret observations of planets in the solar system and beyond.

Focuses on the changes on the surface of the moon. Characteristics of the moon's surface; Association of the moon's surface with the possible image of a dead earth; Discovery of atmosphere surrounding the lunar disk.