The strong stability of most natural motions

Problems of Hamiltonian Mechanics can generally be simplified by some Von Zeipel transformations which reduce the influence of short period parameters and lead to very slowly variable functions: the “quasi-integrals”; however these transformations are implicit and then difficult to use.An explicit construction of the quasi-integrals is presented here and is used to integrate the motion of an artificial satellite perturbed by the zonal harmonics of the Earth gravitational potential; the quasi-integrals are also used to obtain informations on the stability of natural satellites, i.e. lower bounds on the duration of escape or capture.     

Effect of volatile metabolites of dill, radish and garlic on growth of bacteria

In a model experiment plants were grown in sealed chambers on expanded clay aggregate under the luminance of 150 W/m2 PAR and the temperature of 24 degrees C. Seven bacterial strains under investigation, replicated on nutrient medium surface in Petri dishes, were grown in the atmosphere of cultivated plants. Microbial response was evaluated by the difference between colony size in experiment and in control. In control, bacteria grew in the atmosphere of clean air. To study the effects of volatile metabolites of various plant on microbial growth, the experimental data were compared with the background values defined for each individual experiment. Expanded clay aggregate, luminance, temperature, and sealed chamber (without plants) for the background were the same. Volatile metabolites from 28-days old radish plants have been reliably established to have no effect on the growth of microbes under investigation. Metabolites of 30-days old dill and 50-days old garlic have been established to have reliable bacteriostatic effect on the growth of three bacterial strains. Dill and garlic have been found to have different range of effects of volatile substances on bacterial growth. Volatile metabolites of dill and garlic differed in their effect on the sensitivity spectrum of bacteria. An attempt has been made to describe the obtained data mathematically.     

Study of radiation conditions onboard the International space station by means of the Liulin-5 dosimeter

For estimating radiation risk in space flights it is necessary to determine radiation dose obtained by critical organs of a human body. For this purpose the experiments with human body models are carried out onboard spacecraft. These models represent phantoms equipped with passive and active radiation detectors which measure dose distributions at places of location of critical organs. The dosimetric Liulin-5 telescope is manufactured with using three silicon detectors for studying radiation conditions in the spherical tissue-equivalent phantom on the Russian segment of the International space station (ISS). The purpose of the experiment with Liulin-5 instrument is to study dynamics of the dose rate and particle flux in the phantom, as well as variations of radiation conditions on the ISS over long time intervals depending on a phase of the solar activity cycle, orbital parameters, and presence of solar energetic particles. The Liulin-5 dosimeter measures simultaneously the dose rate and fluxes of charged particles at three depths in the radial channel of the phantom, as well as the linear energy transfer. The paper presents the results of measurements of dose rate and particle fluxes caused by various radiation field components on the ISS during the period from June 2007 till December 2009.     

An ethical duty: Let astronautical development unfold – to make the people more secure

In examining alternative space-development models, one observes that Heinlein postulated the first Moon flight as the outcome of the focused action of an individual – building upon an ample commercial aerospace transportation infrastructure. The same technological basis and entrepreneurial drive would then sustain a fast human and economic expansion on three new planets. Instead, historically, humans reached the Moon thanks to a “Faustian bargain” between astronautical developers and governments. This approach brought the early Apollo triumphs, but it also created the presumption of this method as the sole one for enabling space development. Eventually, the application of this paradigm caused the decline of the astronautical endeavor. Thus, just as conventional methods became unable to sustain the astronautical endeavor, space development appeared as vital, e.g., to satisfy the people?s basic needs (metabolic resources, energy, materials, and space), as shown elsewhere. Such an endeavor must grow from actions generating new wealth through commercial activities to become self-supporting. Acquisition and distribution of multiform space resources call, however, for a sound ethical environment, as predatory governments can easily forfeit those resources.     

Postmission plasma volume and red-cell mass changes in the crews of the first two Skylab missions

Red-cell mass determinations were performed before and after the first two Skylab missions. The data showed a 14% mean decrease in red-cell mass after the 28-day mission and a 12% mean decrease after the 59-day mission. The red-cell mass returned to premission levels more slowly after the shorter (28-day) than after the longer mission. Plasma volume decreases were found after each mission. with the crew from the longer mission showing the greater change (13% vs. 8.4%). Postmission decreases in red-cell mass and plasma volume have been a general finding in crewmen who return from short or long spaceflight.     

Inertially fixed pitch stabilization of satellites by solar radiation pressure

Utilization of solar radiation pressure to stabilize the pitch attitude of an unsymmetrical satellite along an inertially-fixed orientation is investigated. A controller employing two rotatable highly reflective control surfaces is proposed and a control strategy involving both nominal and feedback controls is synthesized. Accounting for the apparent annual motion of the Sun, the validity of the concept throughout the year is established through a stability analysis of the system. The influence of the Earth's shadow on the controller performance is also analyzed. The speed of response as well as the pointing accuracy capabilities of the system appear to be quite acceptable for long-life scientific missions.     

French research program on the physiological problems caused by weightlessness. Use of the primate model

The need to acquire a better knowledge of the main biological problems induced by microgravity implies--in addition to human experimentation--the use of animal models, and primates seem to be particularly well adapted to this type of research. The major areas of investigation to be considered are the phospho-calcium metabolism and the metabolism of supporting tissues, the hydroelectrolytic metabolism, the cardiovascular function, awakeness, sleep-awakeness cycles, the physiology of equilibrium and the pathophysiology of space sickness. Considering this program, the Centre d'Etudes et de Recherches de Medecine Aerospatiale, under the sponsorship of the Centre National d'Etudes Spatiales, developed both a program of research on restrained primates for the French-U.S. space cooperation (Spacelab program) and for the French-Soviet space cooperation (Bio-cosmos program), and simulation of the effects of microgravity by head-down bedrest. Its major characteristics are discussed in the study.     

High-speed streams of the solar wind near the earths’s orbit and their sources on the sun according to stereoscopic observations in the minimum of the 23rd cycle

Based on the results of plasma and magnetic measurements at three different points of the heliosphere and telescopic observations of the Sun from these points we study simultaneously high-speed streams (HSS) of the solar wind (SW) near the Earths’s orbit and coronal holes (CH) that have generated them. The data from spacecraft STEREO-A, STEREO-B, ACE, and SOHO are used together with ground-based observations from March 2007 to May 2008. In this period there existed HSS whose sources represented CH of various polarity, geometry, and location relative to the heliographic and heliomagnetic equators. Dependence of SW parameters on mutual positions of spacecraft with respect to CH and heliospheric current sheet, and also on heliolatitude and geometry of the CH is revealed. A difference of more than 5° in locations of spacecraft with respect to the heliospheric current sheet in November 2007 allowed us to discover a heliolatitude velocity gradient of the SW streams between the STEREO-A and STEREO-B spacecraft. On the average this gradient at that time was equal to 20 km/s per degree. Substantial variations in SW streams associated with variations of the HSS SW sources during a few hours or days were also observed. This variability makes it difficult to use the data of spacecraft STEREO-B for sufficiently accurate prediction of SW properties in the near-Earth space by the method of simple advanced ti me shift due to heliolongitude difference between a spacecraft and the Earth even in solar activity minimum.     

Three dimensional temperature field in a conducting sphere due to an arbitrarily located split ring heating source

Thermal control of spacecrafts plays an important role in space missions. In the design stage the preliminary thermal analysis of the spacecraft requires an estimate of the conductive thermal resistance between the various spacecraft components. With this in mind, the fully three dimensional problem of determining the thermal field in a conducting sphere with an asymmetric split ring current carrying heating source is resolved in an analytical or almost analytical form, implying either a closed form solution or utmost expressions involving a simple numerical integration. This has immediate application for evaluation of thermal resistance in spacecrafts. Green's function integral techniques are used. Comparisons are made with series solutions and also with purely numerical solutions to contrast the simplicity and highlight the elegance of the present method. Parametric studies reveal expected behavior.