Element exchange in a water- and gas-closed biological Life Support System.

Liquid human wastes and household water used for nutrition of wheat made possible to realize 24% closure for the mineral exchange in an experiment with a 2-component version of "Bios-3" life support system (LSS) Input-output balances of revealed, that elements (primarily trace elements) within the system. The structural materials (steel, titanium), expanded clay aggregate, and catalytic furnace catalysts. By the end of experiment, the permanent nutrient solution, plants, and the human diet gradually built up Ni, Cr, Al, Fe, V, Zn, Cu, and Mo. Thorough selection and pretreatment of materials can substantially reduce this accumulation. To enhance closure of the mineral exchange involves processing of human-metabolic wastes and inedible biomes inside LSS. An efficient method to oxidize wastes by hydrogen peroxide icon a quartz reactor at the temperature of 80 degrees C controlled electromagnetic field is proposed.     

Plant reproduction systems in microgravity: experimental data and hypotheses.

Elucidation of the possibilities for higher plants to realize complete ontogenesis, from seed to seed, and to propagate by seeds in microgravity, is a fundamental task of space biology connected with the working of the CELSS program. At present, there are results of only 6 spaceflight experiments with Arabidopsis thaliana, an ephemeral plant which will flower and fruit in orbit. Morphogenesis of generative organs occurs normally in microgravity, but unlike the ground control, buds and flowers mainly contain sterile elements of the androecium and gynoecium which degenerate at different stages of development in microgravity. Cytological peculiarities of male and female sterility in microgravity are similar to those occurring naturally during sexual differentiation. Many of the seed formed in microgravity do not contain embryos. Hypotheses to explain abnormal reproductive development in microgravity are: 1) nutritional deficiency, 2) insufficient light, 3) intensification of the influence of the above-mentioned factors by microgravity, 4) disturbances of a hormonal nature, and 5) the absence of pollination and fertilization. Possible ways for testing these hypotheses and obtaining viable seeds in microgravity are discussed.     

Advances in the study of the Middle and Upper Atmosphere

The research activities of the middle and upper atmosphere in China paced abig stride in the recent years. This paper provides an brief overview of theadvances in main aspects of the study in China during the past four years.     

A modelling of the interaction between electromagnetic radiation and West Ford needles clusters: a preliminary study

Radar observations of small space debris made with the Goldstone radar facility have shown that a population of small particles do exist at an altitude larger than 2000 km. This population has been identified with clusters of copper needles created upon the deployment of the West Ford needles project, by MIDAS satellites in 1961 and 1963. This set of particles is either not taken into account in the debris models or only added to other populations. But owing to their specific physical and geometrical properties, the sunlight they scatter could affect, for instance, the spaceborne astronomical experiments. In order to assess this threat it is necessary to model their physical and geometric characteristics. A preliminary modelling using spheres suggests that some improvement is needed. We propose a better approach with long conductive cylinders as a model for the clusters. The interaction of solar light with these particles allows us to estimate the spurious flux scattered inside spaceborne instruments. We conclude that for a given spatial configuration light flashes can affect seriously the operating mode of high sensitivity instruments.     

Evaluating the IRI topside model for the South African region: An overview of the modelling techniques

The representation of the topside ionosphere (the region above the F2 peak) is critical because of the limited experimental data available. Over the years, a wide range of models have been developed in an effort to represent the behaviour and the shape of the electron density (Ne) profile of the topside ionosphere. Various studies have been centred around calculating the vertical scale height (VSH) and have included (a) obtaining VSH from Global Positioning System (GPS) derived total electron content (TEC), (b) calculating the VSH from ground-based ionosonde measurements, (c) using topside sounder vertical Ne profiles to obtain the VSH. One or a combination of the topside profilers (Chapman function, exponential function, sech-squared (Epstein) function, and/or parabolic function) is then used to reconstruct the topside Ne profile. The different approaches and the modelling techniques are discussed with a view to identifying the most adequate approach to apply to the South African region’s topside modelling efforts. The IRI-2001 topside model is evaluated based on how well it reproduces measured topside profiles over the South African region. This study is a first step in the process of developing a South African topside ionosphere model.     

The fundamental physics explorer: An ESA technology reference study

ESA technology reference studies are used as a process to identify key technologies and technical challenges of potential future missions not yet in the science programme. This paper reports on the study of the Fundamental Physics Explorer (FPE), a re-usable platform targeted to small missions testing fundamental laws of physics in space. The study addresses three specific areas of interest: special and general relativity tests based on atomic clocks, experiments on the Weak Equivalence Principle (WEP), and studies of Bose–Einstein condensates under microgravity conditions. Starting from preliminary science objectives and payload requirements, three reference missions in the small/medium class range are discussed, based on a re-adaptation of the LISA Pathfinder spacecraft. A 700/3600 km elliptic orbit has been selected to conduct clock tests of special and general relativity, a 700 km circular orbit to perform experiments on the Weak Equivalence Principle and to study Bose–Einstein condensates, each mission being based on a three-axis stabilised spacecraft. It was determined that adaptation of LISA Pathfinder would be required in order to meet the demands of the FPE missions. Moreover it was established that specific payload and spacecraft technology development would be required to realise such a programme.     

Advances in Researches on the Middle and Upper Atmosphere in 2008-2010

This paper summarizes the results of the researches on the middle and upper atmosphere obtained by Chinese scientists in 2008-2010. The focuses are specifically placed on the researches being associated with ground-based observation capability development, dynamical processes, the property of atmospheric circulation and the chemistry-climate coupling of the middle atmospheric layers.     

Atmosphere sounding by GPS radio occultation: First results from TanDEM-X and comparison with TerraSAR-X

On 21 June 2010 the TerraSAR-X satellite was joined by the TanDEM-X satellite. A Global Positioning System (GPS) radio occultation (RO) experiment using the twin satellites has been carried out to estimate the precision of GPS atmospheric soundings. For the Day Of Year (DOY) 330–336, 2011, we analyze phase and amplitude data recorded by GPS receivers separated by a few hundred meters in a low earth orbit and derive collocated atmospheric refractivity profiles. In the altitude range 10–20 km the standard deviation between TerraSAR-X and TanDEM-X refractivity does not exceed 0.15%. The standard deviation is rapidly increasing for lower and higher altitudes; close to the surface and at an altitude of 30 km the standard deviation reaches 0.8% and 0.5%, respectively. Systematic deviations between TerraSAR-X and TanDEM-X refractivity in the considered altitude range (0–30 km) are negligible. The results confirm the anticipated high precision of the GPS RO technique. However, the difference in the retrieved refractivity in the lower troposphere for different Open Loop (OL) signal tracking parameters, altered onboard TanDEM-X for DOY 49–55, 2012, calls for an in depth analysis. At the moment we can not exclude that a potential bias in the OL Doppler model introduces a bias in our retrieved refractivity at altitudes <8$<8$ km.     

Temporal and spatial variations observed in the ionospheric composition of Venus: Implications for empirical modelling

In situ measurements of the thermal ion composition of the ionosphere of Venus have been obtained for a period of two Venus years from the Bennett rf ion mass spectrometer on the Pioneer Venus Orbiter. Ion measurements within an altitude interval of 160 to 300 kilometers, corresponding to an overall latitude interval of about ?4° to 34°N, are assembled from the interval December 1978 to March 1980. This time interval corresponds to two revolutions of Venus about the Sun, designated as two “diurnal cycles”. The distributions of several ion species in this data base have been sorted to identify temporal and spatial variations, and to determine the feasibility of an analytical representation of the experimental results. The first results from the sorting of several prominent ions including O⁺, O₂⁺, and H⁺ and several minor ions including CO₂⁺, C⁺, and H₂⁺ reveal significant diurnal variations, with superimposed modulation associated with solar activity and solar wind variations. The diurnal variation consists of strong day to night contrast in the ion concentrations, with differences of one to two orders of magnitude, depending upon ion mass and altitude. The concentrations of O₂⁺, O⁺, CO₂⁺ and C⁺ peak throughout the dayside decreasing sharply at the terminators to nightside levels, lower by one to two orders of magnitude relative to the dayside. The diurnal variations of the light ions H⁺ and H₂⁺ peak during the night, exhibiting asymmetric nightside bulges favoring the pre-dawn sector, near 0400 solar hour angle. Superimposed upon the diurnal distributions are modulation signatures which correlate well with modulation in the F_10.7 index, indicating a strong influence of solar variability on the ion production and distribution. The influence of solar wind perturbations upon the ion distributions are also indicated, by a significant increase in the scatter of the observations with increasing altitude as higher altitudes, approaching 300 kilometers, are sampled. Together, these temporal and spatial variations make the task of modelling the ionosphere of Venus both very interesting and challenging.     

On uncertainties in carbon flux modelling and remotely sensed data assimilation: The Brasschaat pixel case

Uncertainty on carbon fluxes is determined by the uncertainties of ecosystem model structure, data and model parameter uncertainties and the temporal and spatial inaccuracy of the input data retrieval. The objective of this paper is to understand the error propagation and uncertainty of evaporative fraction (EF), soil moisture content (SMC) and water limited net ecosystem productivity (NEP). In this respect, C-Fix and spaceborne remote sensing are used for the ‘Brasschaat’ pixel. A simple model based on error theory and a Monte-Carlo approach are used. Different error scenarios are implemented to assess input uncertainty on EF, SMC and NEP as estimated with C-Fix.     

Protecting Earth-orbiting spacecraft against micro-meteoroid/orbital debris impact damage using composite structural systems and materials: An overview

Spacecraft that are launched to operate in Earth orbit are susceptible to impacts by meteoroids and pieces of orbital debris (MMOD). The effect of a MMOD particle impact on a spacecraft depends on where the impact occurs, the size, composition, and speed of the impacting object, the function of the impacted system. In order to perform a risk analysis for a particular spacecraft under a specific mission profile, it is important to know whether or not the impacting particle (or its remnants) will exit the rear of an impacted spacecraft wall. A variety of different ballistic limit equations (BLEs) have been developed for many different types of structural wall configurations. BLEs can be used to optimize the design of spacecraft wall parameters so that the resulting configuration is able to withstand the anticipated variety of on-orbit high-speed impact scenarios. While the level of effort exerted in studying the response of metallic multi-wall systems to high speed particle impact is quite substantial, the extent of the effort to study composite material and composite structural systems under similar impact conditions has been much more limited. This paper presents an overview of the activities performed to assess the resiliency of composite structures and materials under high speed projectile impact. The activities reviewed will be those that have been aimed at increasing the level of protection afforded to spacecraft operating in the MMOD environment, and more specifically, on those activities performed to mitigate the mechanical and structural effects of an MMOD impact.     

Instrumentation and data systems for high-time resolution study of space plasma shocks

This paper deals with the principal methods of achieving high-time resolution measurements for the study of fine structure of shocks and other discontinuities in space plasmas. In the measurements of ion energy spectra, we have obtained the time resolution about 1s.In the Soviet-Czechoslovak INTERSHOCK project we will obtain temporal resolution better than 0.1s in the measurement of the main plasma parameters. This will be obtained with the multichannel energy spectrometer and the on-board data acquisition and processing system triggered by the shock signature. This system controls the data sampling rate from some scientific instruments and switches on a high-sampling rate near the shock. The method implies detecting a shock by means of on-board processing of magnetic field and plasma parameters. The algorithm for this detection uses both parameters separately as well as in combinations.     

Gravisensing in single-celled systems: characean rhizoids and protonemata.

Gravitropically tip-growing cell types are attractive unicellular model systems for investigating the mechanisms and the regulation of gravitropism. Especially useful for studying the mechanisms of positive and negative gravitropic tip-growth are characean rhizoids and protonemata. They originate from the same cell type, show the same overall cell shape, cytoplasmic zonation, arrangement of actin and microtubule cytoskeleton, use statoliths for gravisensing, but show opposite gravitropism. In both cell types, actin microfilaments are complexly organized in the apical dome,where a dense spherical actin array is colocalized with spectrin-like epitopes and a unique endoplasmic reticulum aggregate, the structural center of the Spitzenk?rper. The opposite gravitropic responses seem to be based on differences in the actin-organized anchorage of the Spitzenk?rper and the actin-mediated transport of statoliths. In negatively gravitropic (upward bending) protonemata, the statoliths-induced drastic upward shift of the cell tip is preceded by a relocalization of dihydropyridine-binding calcium channels and of the apical calcium gradient to the upper flank (bending by bulging). Such relocalizations have not been observed in positively gravitropically responding (downward growing) rhizoids in which statoliths sedimentation is followed by differential flank growth (bending by bowing). This paper reviews the current knowledge and hypotheses on the mechanisms of the opposite gravitropic responses in characean rhizoids and protonemata.     

Advances in the Researches of the Middle and Upper Atmosphere in China in 2012–2014

In this report we summarize the research results by Chinese scientists in 2012–2014. The focuses are placed on the researches of the middle and upper atmosphere, specifically the researches related to ground-based observation capability development, dynamical processes, the property of circulation and chemistry-climate coupling of the middle atmospheric layers.     

Land use systems and their impact on environment. An attempt at a classification

The scope and degree of land transformation depends on the system of land use by man. Therefore research on land use systems is of considerable importance, both for better knowledge of resulting processes as well as for more rational land management. To start such research a classification of land use systems is necessary. The paper presents an attempt at such a classification, preceded by an information on the studies carried on in the past as well as an explanation of reasons why such an attempt has been made, followed by the discussion of possible criteria, methods and techniques of land use systems identification.     

Electromagnetic field dissipation and corpuscular bombardment and their implications in atmospheric modelling

The dissipation of energy of electric fields and currents in the polar auroral atmosphere is a major source of energy for the thermosphere ranging locally up to 100 ergs cm^?2 sec^?1 and perhaps more during the most intense disturbance. Globally the input of energy to the thermosphere can often exceed that due to solar EUV radiation. This energy source is always significant in polar regions and its variable strength with respect to that of the solar EUV radiation determines the behaviour of the middle and low latitude thermosphere. It is extremely difficult to model because of its variability in space and time. Nevertheless understanding the dynamics and composition of the global thermosphere is dependent upon incorporation of this source realistically into models. A further important aspect of this energy source is the consequences of its action in changing the density and composition of the thermosphere globally leading to subsequent changes in the absorption of solar EUV radiation. The ring current may also, at times, be a significant source of energy to the low latitude thermosphere.     

Chromosomes and plant cell division in space: environmental conditions and experimental details.

Details of the plant cultivation system developed for the CHROMEX experiment flown aboard the Shuttle Discovery (March, 1989) in NASA's Plant Growth Unit (PGU) are presented. The physical regime as measured during Spaceflight, both within the orbiter cabin environment and within the PGU itself, is discussed. These data function as a guide to what may be representative of the environmental regime in which Space-based plant cultivation systems will be operating, at least for the near-term. Attention is also given to practical considerations involved in conducting a plant experiment in Space. Of particular importance are the differences expected to occur in moisture distribution patterns within substrates used to cultivate plants in Space vs on Earth.     

Gravisensing: ionic responses, cytoskeleton and amyloplast behavior.

In Zea mays L., changes in orientation of stems are perceived by the pulvinal tissue, which responds to the stimulus by differential growth resulting in upward bending of the stem. Gravity is perceived in the bundle sheath cells, which contain amyloplasts that sediment to the new cell base when a change in the gravity vector occurs. The mechanism by which the mechanical signal is transduced into a physiological response is so far unknown for any gravity perceiving tissue. It is hypothesized that this involves interactions of amyloplasts with the plasma membrane and/or ER via cytoskeletal elements. To gain further insights into this process we monitored amyloplast movements in response to gravistimulation. In a pharmacological approach we investigated how the dynamics of plastid sedimentation are affected by actin and microtubule (MT) disrupting drugs. Dark grown caulonemal filaments of the moss Physcomitrella patens respond to gravity vector changes with a reorientation of tip growth away from the gravity vector. MT distributions in tip cells were monitored over time and MTs were seen to accumulate preferentially on the lower flank of the tip 30 min after a 90 degree turn. Using a self-referencing Ca2+ selective ion probe, we found that growing caulonemal filaments exhibit a Ca2+ influx at the apical dome, similar to that reported previously for other tip growing cells. However, in gravistimulated Physcomitrella filaments the region of Ca2+ influx is not confined to the apex, but extends about 60 micrometers along the upper side of the filament. Our results indicate an asymmetry in the Ca2+ flux pattern between the upper and side of the filament suggesting differential activation of Ca2+ permeable channels at the plasma membrane.     

Martian cloud systems: Current knowledge and future observations

In this paper we summarise the current understanding of Martian condensate and dust clouds. The paper is particularly concerned with the spatial, temporal and seasonal characteristics of the clouds. The condensate clouds are composed of water and ice particles and occasionally CO₂ particles. Dust clouds are composed of material from the surface and redistributed over the planet through the weather systems. The apparent lack of annual reproductivity of these dust storms forms a major unresolved problem. We discuss in this paper the types of observations needed in future space missions, in particular the requirements for the NASA Mars Geochemical Climatology Orbiter Mission planned for the end of this decade.