New Frontiers at the Interface of General Relativity and Quantum Optics

In the present paper we follow three major themes: (i) concepts of rotation in general relativity, (ii) effects induced by these generalized rotations, and (iii) their measurement using interferometry. Our journey takes us from the Foucault pendulum via the Sagnac interferometer to manifestations of gravito-magnetism in double binary pulsars and in Gödel’s Universe. Throughout our article we emphasize the emerging role of matter wave interferometry based on cold atoms or Bose–Einstein condensates leading to superior inertial sensors. In particular, we advertise recent activities directed towards the operation of a coherent matter wave interferometer in an extended free fall.     

Determining the Absolute Abundances of Natural Radioactive Elements on the Lunar Surface by the Kaguya Gamma-ray Spectrometer

The Kaguya gamma-ray spectrometer (KGRS) has great potential to precisely determine the absolute abundances of natural radioactive elements K, Th and U on the lunar surface because of its excellent spectroscopic performance. In order to achieve the best performance of the KGRS, it is important to know the spatial response function (SRF) that describes the directional sensitivity of the KGRS. The SRF is derived by a series of Monte Carlo simulations of gamma-ray transport in the sensor of the KGRS using the full-fledged simulation model of the KGRS, and is studied in detail. In this paper, the method for deriving absolute abundance of natural radioactive elements based on the SRF is described for the analysis of KGRS data, which is also applicable to any gamma-ray remote sensings. In the preliminary analysis of KGRS data, we determined the absolute abundances of K and Th on the lunar surface without using any previous knowledge of chemical information gained from Apollo samples, lunar meteorites and/or previous lunar remote sensings. The results are compared with the previous measurements and the difference and the correspondence are discussed. Future detailed analysis of KGRS data will provide new and more precise maps of K, Th and U on the lunar surface.     

Comparisons of foF2 with IRI model and equatorial vertical drifts

Measurements of the critical frequency, foF2 recorded over Ibadan: 7.4°N, 3.9°E (geographic), 6°S (dip angle) have been compared with the International Reference Ionosphere (IRI-2007) model for solar maximum geomagnetically quiet conditions, with a view to determining what modifications might bring about better predictions for the model. Our results reveal that the present version of IRI essentially reproduces diurnal trends and the general features of the experimental observations for all seasons, except for nighttime June solstice periods, which the model seriously overestimated. The model errors ranging from 50% to 125% over the four seasons considered in this study. It is also indicated that the percentage relative deviations between the observed and the modeled values vary approximately from −11% to 12% (March), −34% to 11% (June), −16% to 12% (September), and −10% to 13% (December). An unexpected feature of foF2 is obvious and remarkable reduction in values during nighttime June solstice periods compared to that in other seasons. Relationship between equatorial vertical drift and foF2 is also investigated. However, cross correlation analysis reveals strong anti-correlation between vertical drift and critical frequency during the daytime hours, but exceptionally opposite is the case for the nighttime sector. The discrepancies which are noted, particularly during June solstice season are attributed to processes most likely within the thermosphere and from meteorological influences during quiet magnetic conditions.     

Water and Brines on Mars: Current Evidence and Implications for MSL

Liquid water is a basic ingredient for life as we know it. Therefore, in order to understand the habitability of other planets we must first understand the behavior of water on them. Mars is the most Earth-like planet in the solar system and it has large reservoirs of H₂O. Here, we review the current evidence for pure liquid water and brines on Mars, and discuss their implications for future and current missions such as the Mars Science Laboratory. Neither liquid water nor liquid brines are currently stable on the surface of Mars, but they could be present temporarily in a few areas of the planet. Pure liquid water is unlikely to be present, even temporarily, on the surface of Mars because evaporation into the extremely dry atmosphere would inhibit the formation of the liquid phase, where the temperature and pressure are high enough so that water would neither freeze nor boil. The exception to this is that monolayers of liquid water, referred to as undercooled liquid interfacial water, could exist on most of the Martian surface. In a few places liquid brines could exist temporarily on the surface because they could form at cryogenic temperatures, near ice or frost deposits where sublimation could be inhibited by the presence of nearly saturated air. Both liquid water and liquid brines might exist in the shallow subsurface because even a thin layer of soil forms an effective barrier against sublimation allowing pure liquid water to form sporadically in a few places, or liquid brines to form over longer periods of time in large portions of the planet. At greater depths, ice deposits could melt where the soil conductivity is low enough to blanket the deeper subsurface effectively. This could cause the formation of aquifers if the deeper soil is sufficiently permeable and an impermeable layer exists below the source of water. The fact that liquid brines and groundwater are likely to exist on Mars has important implications for geochemistry, glaciology, mineralogy, weathering and the habitability of Mars.     

Statistical modelling of radio wave propagation under sporadic E-Layer influence

A technique of modelling the one-hop radio wave propagation at middle latitudes in the presence of sporadic E-Layer is presented. The technique is focused on the performance of the long-term forecast of the maximum usable frequency range and on the increase of the radio communication reliability. Examples of calculation for medium-distance paths are shown.     

Methods for Characterising Microphysical Processes in Plasmas

Advanced spectral and statistical data analysis techniques have greatly contributed to shaping our understanding of microphysical processes in plasmas. We review some of the main techniques that allow for characterising fluctuation phenomena in geospace and in laboratory plasma observations. Special emphasis is given to the commonalities between different disciplines, which have witnessed the development of similar tools, often with differing terminologies. The review is phrased in terms of few important concepts: self-similarity, deviation from self-similarity (i.e. intermittency and coherent structures), wave-turbulence, and anomalous transport.     

Experimental studies of free flow boundaries influence upon aerodynamic characteristics of the clean large-scale models

In this paper, the expediency of increasing the relative sizes in clean models of wings and aircraft layouts in the low-speed open working section wind tunnels with a circular nozzle section is considered. Also determined is an additional correction, which makes it possible to take into account the external atmospheric pressure influence upon the aerodynamic characteristics of large-scale models and enhance the efficiency of the low-speed wind tunnels.     

Simulation of pulsating channel flows

A method for simulating spatial-temporary characteristics of pulsating flows in the varying-in-length-area channels based on the solution of one-dimensional nonstationary equations of gas dynamics is presented. The calculation results are compared with the experimental data, and it is shown that the method being proposed rather adequately simulates real processes in complex unsteady flows.     

The Origin and Evolution of the Asteroid Belt��Implications for Vesta and Ceres

Vesta and Ceres are the largest members of the asteroid belt, surviving from the earliest phases of Solar System history. They formed at a time when the asteroid belt was much more massive than it is today and were witness to its dramatic evolution, where planetary embryos were formed and lost, where the collisional environment shifted from accretional to destructive, and where the current size distribution of asteroids was sculpted by mutual collisions and most of the asteroids originally present were lost by dynamical processes. Since these early times, the environment of the asteroid belt has become relatively quiescent, though over the long history of the Solar System the surfaces of Vesta and Ceres continue to record and be influenced by impacts, most notably the south polar cratering event on Vesta. As a consequence of such impacts, Vesta has contributed a significant family of asteroids to the main belt, which is the likely source of the HED meteorites on Earth. No similar contribution to the main belt (or meteorites) is evident for Ceres. Through studies of craters, the surfaces of these asteroids will offer an opportunity for Dawn to probe the modern population of small asteroids in a size regime not directly observable from Earth.     

Equatorial total electron content (TEC) at low and high solar activity

Total electron content (TEC) derived from ionosonde data recorded at the station of Korhogo (Lat = 9.33°N, Long = 5.43°W, Dip = 0.67°S) are compared to the International Reference Ionosphere (IRI) model predicted TEC for high (1999) and low (1994) solar activity conditions. The results show that the model represents the diurnal variation of the TEC as well as a solar activity and seasonal dependence. This variation is closer to that of the ionosonde-inferred TEC at high solar activity. However, at low solar activity the IRI overestimates the ionosonde-inferred TEC. The relative deviation ΔTEC is more prominent in the equinoctial seasons during nighttime hours where it is as high as 70%. At daytime hours, the relative deviation is estimated to 0–30%.