Determination of the density and percentage of metal oxides in the lunar soil based on radar data

Results of laboratory measurements of the dielectric characteristics of lunar soil samples returned to the Earth by the Luna and Apollo missions have been analyzed. The feasibility of determining the density of the upper cover of the Moon from the permittivity, which is restored as a result of solving the inverse problem of radiolocation, has been discussed. A formula has been proposed for approximating the frequency dependence of the loss tangent for the regolith and bedrock. Relationships have been deduced for estimating the percentage of metal oxides in the lunar soil.     

Education programme on aerospace and environmental medicine for medical faculty of Lomonosov Moscow State University.

The problems and approaches to organisation of the education process in the field of aerospace and environmental medicine for medical students are discussed. Original education developed on the basis of Russian experience in space biology and physiology, environmental medicine, aerospace medicine and medical support during spaceflight. The main goals of these programs are to acquaint students with: interaction of living organisms with natural and artificial surroundings, including space flight conditions; the physiological reactions on extreme environmental factors; basic mechanisms of human adaptation to space flight and particularly to microgravity; the current research in space medicine and new telecommunication technologies. All programs are formed in accordance with contemporary progress in life sciences and revealed a result of the interdisciplinary approach to education process.     

ISEE Ion Composition Data with Implications for Solar Wind Entry into Earth's Magnetotail

Energetic (0.1-16 keV/e) ion data from a plasma composition experiment on the ISEE-1 spacecraft show that Earth's plasma sheet (inside of 23 RE) always has a large population of H+ and He++ ions, the two principal ionic components of the solar wind. This population is the largest, in terms of both number density and spatial thickness, during extended periods of northward interplanetary magnetic field (IMF) and is then also the most "solar wind-like" in the sense that the He++/H+ density ratio is at its peak (about 3% on average in 1978 and 79) and the H+ and He++ have mean (thermal) energies that are in the ratio of about 1:4 and barely exceed the typical bulk flow energy in the solar wind. During geomagnetically active times, associated with southward turnings of the IMF, the H+ and He++ are heated in the central plasma sheet, and reduced in density. Even when the IMF is southward, these ions can be found with lower solar wind-like energies closer to the tail lobes, at least during plasma sheet thinning in the early phase of substorms, when they are often seen to flow tailward, approximately along the magnetic field, at a slow to moderate speed (of order 100 km s-1 or less). These tailward flows, combined with the large density and generally solar wind-like energies of plasma sheet H+ and He++ ions during times of northward IMF, are interpreted to mean that the solar wind enters along the tail flanks, in a region between the lobes and the central plasma sheet, propelled inward by ExB drift associated with the electric fringe field of the low latitude magnetopause boundary layer (LLBL). In order to complete this scenario, it is argued that the rapid (of order 1000 km s-1) earthward ion flows (mostly H+ ions), also along the magnetic field, that are more typically the precursors of plasma sheet "recovery" during substorm expansion, are not proof of solar wind entry in the distant tail, but may instead be a time-of-flight effect associated with plasma sheet redistribution in a dipolarizing magnetic field.     

Morphology and physics of short-period magnetic pulsations

This review is devoted to the main problems of experimental and theoretical investigations of geoelectromagnetic waves in the frequency range from 0.1 to 5 Hz. These waves constitute the short-period subclass of so-called geomagnetic pulsations. The short-period pulsations are represented by Pc1, Pc2, Pi1, Ipdp types and some subclassifications. The understanding of the pulsation mechanisms provides an insight into the structure and dynamics of the Earth's magnetosphere. We focus our attention on Pc1 pearl pulsations and on the classical (evening) Ipdp, for which basic physical concepts have been established. Other types and varieties are outlined also, but in less detail. In these cases, the physical mechanism is not always clear (as, for example, in the case of morning Ipdp), and/or the morphology is still to be determined carefully (Pc2 and discrete signals in polar cusps as typical examples).Short-period pulsations are a spontaneous, sporadic phenomenon which undergo a certain evolution in the course of a magnetic storm. We consider the storm-time variation as a natural background, and we use this background to collect the information about the pulsations in an orderly manner. At the same time, together with the transient storm-time variation of pulsation activity, quasi-periodic variations take place, which are connected with the Earth's and Sun's rotation, Earth's orbital motion and solar cycle activity. The study of these regular variations allows us to have a new approach to the mechanisms of excitation and propagation of short-period geomagnetic pulsations.     

X-ray emission from cataclysmic variables

EXOSAT results on cataclysmic variables are reviewed. The long continuous X-ray observations afforded by this observatory, coupled with the sensitivity of its instruments to medium energy and very low energy X-rays, have enabled the rotational and orbital X-ray light curves of these stars to be measured in unprecedented detail. Examples are given of data on synchronously and asynchronously rotating magnetic systems, and on disc accreting stars. The impact of the new observations on our understanding of cataclysmic variables is discussed.     

An EXOSAT observation of the peculiar X-ray binary 2S 0921-630 during optical eclipse

An x-ray observation of 2S 0921-630 has been made coincident with the time of optical eclipse of this 9-day binary. No significant reduction in X-ray flux is measured. This can be explained if the binary orbit is viewed almost exactly edge-on, so that the central X-ray emitting star is obscured by the accretion disk from direct view. The X-rays that are seen are scattered into the line of sight by material above and below the disk and the apparent size of the X-ray emission region is thus large compared to the size of the occulting star.     

Medium energy neutral atom (MENA) imager for the IMAGE mission

The Medium Energy Neutral Atom (MENA) imager was developed in response to the Imaging from the Magnetopause to the Aurora for Global Exploration (IMAGE) requirement to produce images of energetic neutral atoms (ENAs) in the energy range from 1 to 30 keV. These images will be used to infer characteristics of magnetospheric ion distributions. The MENA imager is a slit camera that images incident ENAs in the polar angle (based on a conventional spherical coordinate system defined by the spacecraft spin axis) and utilizes the spacecraft spin to image in azimuth. The speed of incident ENAs is determined by measuring the time-of-flight (TOF) from the entrance aperture to the detector. A carbon foil in the entrance aperture yields secondary electrons, which are imaged using a position-sensitive Start detector segment. This provides both the one-dimensional (1D) position at which the ENA passed through the aperture and a Start time for the TOF system. Impact of the incident ENA on the 1D position-sensitive Stop detector segment provides both a Stop-timing signal and the location that the ENA impacts the detector. The ENA incident polar angle is derived from the measured Stop and Start positions. Species identification (H vs. O) is based on variation in secondary electron yield with mass for a fixed ENA speed. The MENA imager is designed to produce images with 8°×4° angular resolution over a field of view 140°×360°, over an energy range from 1 keV to 30 keV. Thus, the MENA imager is well suited to conduct measurements relevant to the Earth's ring current, plasma sheet, and (at times) magnetosheath and cusp.     

Gradient pattern analysis of short solar radio bursts

We analyze the weak component of the localized temporal pattern variability of 3 GHz solar burst observed by the Ondrejov radiospectrograph. A complex, short and weak impulsive sample from the time series was analyzed by applying a method based on the gradient pattern analysis and discrete wavelet decomposition. By analyzing canonical temporal variability patterns we show that the new method can reliably characterize the phenomenological dynamical process of short time series (N ? 10³ measurements) as the radio burst addressed here. In the narrowest sense, by estimating the mutual information distance in the gradient spectra, we show that the fluctuation pattern of the short and weak 3 GHz impulsive solar burst, with energetic amplitudes <350 SFU, is closer to the intermittent and strong MHD turbulent variability pattern.