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The Moon and Mercury are airless bodies, thus they are directly exposed to the ambient plasma (ions and electrons), to photons mostly from the Sun from infrared range all the way to X-rays, and to meteoroid fluxes. Direct exposure to these exogenic sources has important consequences for the formation and evolution of planetary surfaces, including altering their chemical makeup and optical properties, and generating neutral gas exosphere. The formation of a thin atmosphere, more specifically a surface bound exosphere, the relevant physical processes for the particle release, particle loss, and the drivers behind these processes are discussed in this review.

Nanoscale Fourier transform infrared (Nano-FTIR) imaging and spectroscopy correlated with photoluminescence measurements of lunar Apollo samples with different surface radiation exposure histories reveal distinct physical and chemical differences associated with space weathering effects. Analysis of two sample fragments: an ilmenite basalt (12016) and an impact melt breccia (15445) show evidence of intrinsic or delivered Nd 3+ and an amorphous silica glass component on exterior surfaces, whereas intrinsic Cr 3+ and/or trapped electron states are limited to interior surfaces. Spatially localized 1050 cm −1 /935 cm −1 band ratios in Nano-FTIR hyperspectral maps may further reflect impact-induced shock nanostructures, while shifts in silicate band positions indicate accumulated radiation damage at the nanoscale from prolonged space weathering due to micrometeorites, solar wind, energetic x-rays and cosmic ray bombardment. Our observations demonstrate that space weathering alterations of the surface of lunar samples at the nanoscale may provide a mechanism to distinguish lunar samples of variable surface exposure age.

This paper deals with situations that illustrate how the violation of Lorentz symmetry in the gauge sector may contribute to magnetic moment generation of massive neutral particles with spin- and spin-1. The procedure we adopt here is based on Relativistic Quantum Mechanics. We work out the non-relativistic regime that follows from the wave equation corresponding to a certain particle coupled to an external electromagnetic field and a background that accounts for the Lorentz-symmetry violation, and we thereby read off the magnetic dipole moment operator for the particle under consideration. We keep track of the parameters that govern the non-minimal electromagnetic coupling and the breaking of Lorentz symmetry in the expressions we get for the magnetic moments in the different cases we contemplate. Our claim is that the tiny magnetic dipole moment of truly-elementary neutral particles might signal Lorentz-symmetry violation.

Widespread hydration was detected on the lunar surface through observations of a characteristic absorption feature at 3 µm by three independent spacecraft 1 – 3 . Whether the hydration is molecular water (H 2 O) or other hydroxyl (OH) compounds is unknown and there are no established methods to distinguish the two using the 3 µm band 4 . However, a fundamental vibration of molecular water produces a spectral signature at 6 µm that is not shared by other hydroxyl compounds 5 . Here, we present observations of the Moon at 6 µm using the NASA/DLR Stratospheric Observatory for Infrared Astronomy (SOFIA). Observations reveal a 6 µm emission feature at high lunar latitudes due to the presence of molecular water on the lunar surface. On the basis of the strength of the 6 µm band, we estimate abundances of about 100 to 400 µg g −1 H 2 O. We find that the distribution of water over the small latitude range is a result of local geology and is probably not a global phenomenon. Lastly, we suggest that a majority of the water we detect must be stored within glasses or in voids between grains sheltered from the harsh lunar environment, allowing the water to remain on the lunar surface. The Stratospheric Observatory for Infrared Astronomy (SOFIA) looked at the Moon in the 6 µm wavelength region and found a signature of molecular water, distinguishing it from other forms of hydration. The authors estimate water abundances between 100 and 400 µg g − 1 at high latitudes, trapped within impact glasses or possibly in between grains.

The signature of condensed molecular oxygen has been reported in recent optical-reflectance measurements of the jovian moon Ganymede 1 , and a tenuous oxygen atmosphere has been observed on Europa 2 . The surfaces of these moons contain large amounts of water ice, and it is thought that O 2 is formed by the sputtering ofice by energetic particles from the jovian magnetosphere 3 , 4 , 5 , 6 , 7 , 8 . Understanding how O 2 might be formed from low-temperature ice is crucial for theoretical and experimental simulations of the surfaces and atmospheres of icy bodies in the Solar System. Here we report laboratory measurements of the threshold energy, cross-section and temperature dependence of O 2 production by electronic excitation of ice in vacuum, following electron-beam irradiation. Molecular oxygen is formed by direct excitation and dissociation of a stable precursor molecule, rather than (as has been previously thought) by diffusion and chemical recombination of precursor fragments. The large cross-section for O 2 production suggests that electronic excitation plays an important part in the formation of O 2 on Ganymede and Europa.

Solar wind implantation is thought to be one of the primary mechanisms in the formation of water (OH/H2O) on the surface of the Moon and possibly on the surface of other airless bodies. The lunar nearside spends ~27% of its daytime in Earth’s magnetotail where the solar wind flux is reduced by as much as ~99%. However, no correlated decrease in surficial water content has yet been seen on the lunar nearside. Here we report abundance observations of lunar surficial water on the nearside at different stages during the Moon’s passage through Earth’s magnetotail. We find that the water abundance at lunar mid-latitudes substantially increases in the dusk and dawn magnetosheath when the solar wind flux increases, yet remains nearly constant across the central magnetotail. We suggest that although we have confirmed the importance of the solar wind as a major source of fast water production on the Moon, hitherto unobserved properties of the plasma sheet properties may also play an important role.Measurements of the abundance of nearside lunar surface water at various positions of the Moon during the crossing of Earth’s magnetotail bring evidence of the existence of processes of water formation linked to the plasma sheet.

One of the most challenging fundamental problems in establishing prebiotically plausible routes for phosphorylation reactions using phosphate is that they are thermodynamically unfavorable in aqueous conditions. Diamidophosphate (DAP), a potentially prebiotically relevant compound, was shown to phosphorylate nucleosides in aqueous medium, albeit at a very slow rate (days/weeks). Here, we demonstrate that performing these reactions within an aerosol environment, a suitable model for the early Earth ocean-air interface, yields higher reaction rates when compared to bulk solution, thus overcoming these rate limitations. As a proof-of-concept, we demonstrate the effective conversion (~6.5–10%) of uridine to uridine-2′,3′-cyclophosphate in less than 1 h. These results suggest that aerosol environments are a possible scenario in which prebiotic phosphorylation could have occurred despite unfavorable rates in bulk solution.

We consider a N – S box system consisting of a rectangular conductor coupled to a superconductor. The Green functions are constructed by solving the Bogoliubov-de Gennes equations at each side of the interface, with the pairing potential described by a step-like function. Taking into account the mismatch in the Fermi wave number and the effective masses of the normal metal – superconductor and the tunnel barrier at the interface, we use the quantum section method in order to find the exact energy Green function yielding accurate computed eigenvalues and the density of states. Furthermore, this procedure allow us to analyze in detail the nontrivial semiclassical limit and examine the range of applicability of the Bohr-Sommerfeld quantization method.

The Aharonov-Bohm-Casher problem is examined for a charged particle describing a circular path in presence of a Lorentz-violating background nonminimally coupled to a spinor and a gauge field. It were evaluated the particle eigenenergies, showing that the LV background is able to lift the original degenerescence in the absence of magnetic field and even for a neutral particle. The Aharonov-Casher phase is used to impose an upper bound on the background magnitude. A similar analysis is accomplished in a space endowed with a topological defect, revealing that both the disclination parameter and the LV background are able to modify the particle eigenenergies. We also analyze the particular case where the particle interacts harmonically with the topological defect and the LV background, with similar results.

A remarkable hardening (~ 30 cm-1) of the normal mode of vibration associated with the symmetric stretching of the oxygen octahedra for the Ba2FeReO6 and Sr2CrReO6 double perovskites is observed below the corresponding magnetic ordering temperatures. The very large magnitude of this effect and its absence for the anti-symmetric stretching mode provide evidence against a conventional spin-phonon coupling mechanism. Our observations are consistent with a collective excitation formed by the combination of the vibrational mode with oscillations of local Fe or Cr 3d and Re 5d occupations and spin magnitudes.