PKE-Nefedov — Complex plasma research on the international space station

Complex plasma research is a new and rapidly developing field, with investigations under gravity and microgravity conditions. The complex plasma consists of a common plasma — with electrons, ions and neutrals — and an additional component of small solid particles typically in the range of micrometers. This heavy component in the plasma makes it necessary to perform experiments under microgravity conditions although it is possible to levitate the particles in the laboratory as well. The microparticles in the plasma are charged through the absorption of free electrons and ions to thousands of elementary charges. On Earth, the particles can be levitated in a strong electric field. But this induces stresses to the particle cloud which can only be eliminated under microgravity conditions. It also implies that under gravity conditions only a small part of the parameter phase space of complex plasmas can be investigated. Therefore, to complete the research on complex plasmas, investigations under microgravity conditions are mandatory. This paper overviews the research on complex plasmas on the International Space Station ISS achieved with the first long-term experiment, PKE-Nefedov, used for this research.     

A massive bolometer on the international space station to measure energy deposition by the space radiation environment

We describe a novel space-based low-temperature radiation detector, the “Particle Heating Detector” (PhD), which was recently selected to be part of the first mission of the Low-Temperature Microgravity Physics Facility, scheduled to fly on the International Space Station in 2008. This massive bolometer will measure total heating induced in an aluminum absorber by the space radiation environment. The use of paramagnetic alloy thermometers with SQUID readout, giving resolution, combined with a large-area absorber, will enable the detector to perform high-resolution, real-time measurement of the low energy deposition levels caused by galactic cosmic rays in low-Earth orbit.     

Evaluation of solid state nuclear track detector stacks exposed on the international space station

The aim of the study was to investigate the contribution of secondary neutrons to the total dose inside the International Space Station (ISS). For this purpose solid-state nuclear track detector (SSNTD) stacks were used. Each stack consisted of three CR-39 sheets. The first and second sheets were separated by a Ti plate, and the second and third sheets sandwiched a Lexan polycarbonate foil. The neutron and proton responses of each sheet were studied through MC calculations and experimentally, utilising monoenergetic protons. Seven stacks were exposed in 2001 for 249 days at different locations of the Russian segment 'Zvezda'. The total storage time before and after the exposure onboard was estimated to be seven months. Another eight stacks were exposed at the CERF high-energy neutron field for calibration purposes. The CR-39 detectors were evaluated in four steps: after 2, 6, 12 and 20 h etching in 6 N NaOH at 70 degrees C (VB = 1.34 microm h(-1)). All the individual tracks were investigated and recorded using an image analyser. The stacks provided the averaged neutron ambient dose equivalent (H*) between 200 keV and 20 MeV, and the values varied from 39 to 73 microSv d(-1), depending on the location. The Lexan detectors were used to detect the dose originating from high-charge and high-energy (HZE) particles. These results will be published elsewhere.     

From waste to energy: First experimental bacterial fuel cells onboard the international space station

Bacterial Fuel Cells are innovative energy systems that use bacteria to transform carbohydrates anaerobically into free electrons and waste products. The bacteria deposit the electrons on the anode and hence create a potential difference between the anode and the cathode, yielding a ‘bacterial battery’. This principle may be favourably influenced by enhanced bacterial productivity or bacterial growth in microgravity conditions, as is shown before in several other studies on bacteria in microgravity. Nonetheless, bacterial fuel cells have not been tested in space before. Currently foreseen applications are very promising for space flight and include waste disposal in manned space vehicles. This study describes a ‘space-first’test of bacterial fuel cells onboard the International Space Station using the Rhodoferax ferrireducens strain. We test if it is possible to use a bacterial fuel cell in 1g and under both simulated (RPM) and real microgravity conditions. Due to differences in magnitude of the output the data had to be normalized and cumulatively plotted. In all, it can be concluded that bacterial fuel cells show similar phases in the output under different gravitational conditions. Hence it can be concluded from a biological point of view that bacterial fuel cells do operate in space.     

Microbial detection and monitoring in advanced life support systems like the international space station

Potentially pathogenic microbes and so-called technophiles may form a serious threat in advanced life support systems, such as the International Space Station (ISS). They not only pose a threat to the health of the crew, but also to the technical equipment and materials of the space station. The development of fast and easy to use molecular detection and quantification methods for application in manned spacecraft is therefore desirable and may also be valuable for applications on Earth. In this paper we present the preliminary results of the SAMPLE experiment in which we performed molecular microbial analysis on environmental samples of the ISS as part of an ESA-MAP project.     

Main results of LSO (Lightning and sprite observations) on board of the international space station

The experiment LSO (Lightning and Sprite Observations), on board of the International Space Station, was the first experiment dedicated to nadir observations of sprites from space. Such observations are innovative as sprites are generally observed at the horizon. At the nadir, sprites are superimposed with lightning flashes and the observation concept is based on a spectral differentiation of sprites and lightning by using an adapted filter. The experiment is composed of two micro-cameras, fixed on a station window. One camera is equipped with a filter and measures the sprites in the N2 1P most intense sprite emission line, which coincides also to the atmospheric absorption band of the molecular oxygen. The second microcamera provides observations of lightning flashes in the visible. Measurements were performed during four ESA missions: Andromede, Odissea, Cervantes and Delta. During 19h of effective observations, 180 flashes were analyzed and several possible sprites were identified, demonstrating the interest of this differentiation method. In addition during sunset and sunrise conditions when the lower atmosphere is in the dark, LSO observed the airglow of the secondary ozone maximum at about 90 km modulated by gravity wave activity.     

The “ageing” experiment in the spanish soyuz mission to the international space station

Human exploration of outer space will eventually take place. In preparation for this endeavour, it is important to establish the nature of the biological response to a prolonged exposure to the space environment. In one of the recent Soyuz Missions to serve the International Space Station (ISS), the Spanish Soyuz mission in October 2003, we exposed four groups of Drosophila male imagoes to microgravity during the almost eleven days of the Cervantes mission to study their motility behaviour. The groups were three of young flies and one of mature flies, In previous space experiments, we have shown that when imagoes are exposed to microgravity they markedly change their behaviour by increasing their motility, especially if subjected to these conditions immediately after hatching. The constraints of the current Soyuz flights made it impossible to study the early posthatching period. A low temperature cold transport was incorporated as a possible way out of this constraint. It turned out that on top of the space flight effects, the cold treatment by itself, modifies the motility behaviour of the flies. Although the four groups increased their motility, the young flies did it in a much lower extent than the mature flies that had not been exposed to the low temperature during transportation. Nevertheless, the flies flown in the ISS are still more active than the parallel ground controls. As a consequence of the lower motility stimulation in this experiment, a likely consequence of the cold transport step, no effects on the life spans of the flown flies were detected. Together with previous results, this study confirms that high levels of motility behaviour are necessary to produce significant decreases in fly longevity.     

Mini-see project to measure the parameters of gravitational interaction using the alpha international space station

The behavior of two bodies interacting gravitationally onboard a drift-free Earth satellite orbiting at the altitudes of the Alpha international space station is investigated. A numerical simulation of the trajectories of the relative motion of aparticle is performed, as a result of which preliminary estimates of the precision of the experiment are obtained. An estimate of the measurement precision of the parameters of gravitational interaction is given. Translated from Izmeritel'naya Tekhnika, No. 10, pp. 3–8, October, 1997.     

Design and test of an electronic nose for monitoring the air quality in the international space station

Long-term manned space missions requires a continuous monitoring of the air quality inside the spacecraft. For this scope, among several different solutions, electronic noses have been considered. On behalf of European Space Agency an electronic nose specifically designed for air quality control in closed environment is under development. After several ground experiments concerning the monitoring of a biofilter efficiency, the instrument has been tested during the ENEIDE mission on board of the International Space Station. in this paper the instrument main concepts and its performance in ground and space experiments are illustrated.     

A multiparameter converter for recording the location of an air leak from the international space station

A multiparameter instrument for recording the location of an air leak from the space station module, based on three sensors, namely, electret, thermocouple and an ionization separator, is proposed. The regions of greatest reliability of the measurements of each of the sensors are determined and the recorded air leak uncertainty zones are pointed out.     

Development of neuronal and sensorimotor systems in the absence of gravity: Neurobiological research on four soyuz taxi flights to the international space station

Neurobiological experiments on 4 animal species (Xenopus laevis, Pleurodeles waltl, Drosophila melanogaster, Acheta domesticus) were performed to study effects of microgravity on development and aging of neuronal, sensory and motor systems. Animal models were selected according to their suitability to answer questions concerning μg-effects on neuroanatomy, neuronal activity, and behaviour. The studies were performed on the Soyuz Taxi flights Andromède, Cervantes, Eneide and LDM-TMA8/TMA7. Observations from these flights include: (1) In tadpoles and cricket larvae, morphological features of sensory cells and neurons are rarely affected by microgravity. (2) In crickets, in-flight fertilization was successful; after landing, flight larvae hatched earlier than ground reared siblings. (3) In crickets, proliferation of peptidergic neurons and their projection patterns within the nervous system were not affected by microgravity. (4) During aging, the impact of microgravity on peptidergic neurons of male Drosophila was limited to the size of cell body. (5) In Xenopus, neurophysiological features of the spinal motor system during fictive swimming were partially modified. (6) In Xenopus tadpoles, the vestibuloocular reflex was affected in an age-related manner. Modifications were also related to the occurrence of a tail lordosis induced by microgravity. It is concluded that adaptation to microgravity during development and aging is mainly based on physiological mechanisms within the central nervous system while structural modifications of the sensory and neuronal system contribute less.     

Counterdiffusion protein crystallisation in microgravity and its observation with PromISS (protein microscope for the international space station)

The crystallisation by counterdiffusion is a very efficient technique for obtaining high-quality protein crystals. A prerequisite for the use of counterdiffusion techniques is that mass transport must be controlled by diffusion alone. Sedimentation and convection can be avoided by either working in gelled systems, working in systems of small dimensions, or in the absence of gravity. We present the results from experiments performed on the ISS using the Protein Microscope for the International Space Station (PromISS), using digital holography to visualise crystal growth processes. We extensively characterised three model proteins for these experiments (cablys3*lysozyme, triose phosphate isomerase, and parvalbumin) and used these to assess the ISS as an environment for crystallisation by counterdiffusion. The possibility to visualise growth and movement of crystals in different types of experiments (capillary counterdiffusion and batch-type) is important, as movement of crystals is clearly not negligible.     

Micrometeroid and debris impact test on space station bumper

To design the micrometeoroid and debris protection bumper of the outboard structure space station module, we made a two-stage helium light gas gun and carried out hypervelocity impact tests which simulated micrometeroid and debris impacts on space station. Fundamental characteristics of hypervelocity impact phenomena was investigated, for a projectile mass 0.45gr to 1.5gr, impact velocity about 4km/sec and aluminum-alloy bumpers. When the bumper is of double-sheet type, there exists an optimal front sheet thickness that causes melting of the front sheet. However, for thin front sheets, penetration occurs, and for thick front sheets, spall fracture occurs. In addition to the impact tests, the computational simulation of the typical test result was carried out using the PISCES code with the Tillotson constitut ive equation of aluminum-alloy. The computational sumulation result had a good agreement with the test result.     

The effect of thin deployable construction elements of the international space station on the probability of its hull penetration by meteoroids and orbital debris

When calculating the probability of hull penetration by meteoroid and orbital debris (M/OD) for some of the International Space Station (ISS) modules (e.g. FGB, Service module, cargo vehicle “Progress”), one has to take into account their additional shielding produced by ISS deployable construction elements (such as solar panels, radiators), which decrease M/OD penetrating probabilities. The lack of developed calculation methods of accounting for this effect has arisen the necessity to investigate the law— governed nature of particle fragmentation process accompanying high velocity penetration of thin barriers, as well as to elaborate techniques for correct calculation of the probability of no penetration (PNP) of module pressure wall. The results of thorough analysis of the theoretical and experime ntal published data as well as of data obtained in joint NASA and RSA experimental program on particle fragmentation are presented in this report in the form of normalized analytical correlation between the fragment maximum size and impact parameters. On the basis of above mentioned particle fragmentation law, the method of module hull ballistic limit curves (BLC's) recalculation is determined, which include the effect of thin barriers greatly distanced from the module hull. This BLC's are used for module PNP calculations with the help of modified version of NASA BUMPER code. The special subroutines accounting for PNP changes due to the particle collisions with ISS deployable construction elements are introduced in the BUMPER algorithm. The results of the Service module PNP calculations with account for its “shadowing” by solar panels and radiators are presented.     

The effect of simulated microgravity on bacteria from the mir space station

The effects of simulated microgravity on two bacterial isolates, Sphingobacterium thalpophilium and Ralstonia pickettii (formerly Burkholderia pickettii), originally recovered from water systems aboard the Mir space station were examined. These bacteria were inoculated into water, high and low concentrations of nutrient broth and subjected to simulated microgravity conditions. S. thalpophilium (which was motile and had flagella) showed no significant differences between simulated microgravity and the normal gravity control regardless of the method of enumeration and medium. In contrast, for R. pickettii (that was non-motile and lacked flagella), there were significantly higher numbers in high nutrient broth under simulated microgravity compared to normal gravity. Conversely, when R. pikkettii was inoculated into water (i.e., starvation conditions) significantly lower numbers were found under simulated microgravity compared to normal gravity. Responses to microgravity depended on the strain used (e.g., the motile strain exhibited no response to microgravity, while the non-motile strain did), the method of enumeration, and the nutrient concentration of the medium. Under oligotrophic conditions, non-motile cells may remain in geostationary orbit and deplete nutrients in their vicinity, while in high nutrient medium, resources surrounding the cell may be sufficient so that high growth is observed until nutrients becoming limiting.     

空间站展开机构的失谐动态响应分析

考虑了动力失谐、质量失谐和摩擦失谐三种常见失谐现象,研究了空间站展开机构的失谐动态响应。利用多柔体系统动力学方法,在机械系统动力学自动分析(ADAMS)仿真平台下建立了空间站柔性展开机构的失谐模型,并用重要度抽样方法随机抽取失谐量,然后进行机构动学仿真,得到机构的失谐动态响应并进行统计。仿真研究证明,该方法可用较少的计算时间得到柔性展开机构的失谐动态响应随机分布特性。     

COST 90: Results of an international project on thermal properties

COST 90 thermophysical properties represents a new step to supply the food engineer with reliable data for process calculations and modelling for optimisation. On the basis of available information, calculation methods have been developed for thermophysical properties from data on composition and basic physical properties. The few data which exist for verification indicate some limitations but also the general potential of such an approach, which favours a closer co-operation between existing analytical centres for food composition and technological laboratories. The incorporation of simple physical data such as density and initial freezing point in existing tables of basic constituents of foodstuffs would make available a full set of data for the prediction of thermophysical properties.     

PbS-Si heterojunctions: Growth and structural properties

The PbS-Si (1 1 1) heterostructures were fabricated by various chemical methods. lt has been observed that uniform single and multilayer PbS films, which are mostly polycrystalline, could be prepared. Strongly oriented films have also been deposited by the Davis and Norr method. Substrate preparation prior to the deposition of the films, is found to have a more pronounced effect on the first layer, rather than on the subsequent layers. Orientation of these films is observed to change with the thickness and etchants used in this study. As film thickness increases, size defects and strain defects decrease for these heterostructures. An anisotropy is noted in domain size end strain in these films.     

Growth of international collaboration in science: revisiting six specialties

Scientometrics - International collaboration in science continues to grow at a remarkable rate, but little agreement exists about dynamics of growth and organization at the discipline level. Some...     

Microdosimetric spectra and LET distributions on board the Mir space station obtained with a particle track detector

A spectrometer measuring energy lost (deltaE) was used to determine linear energy transfer (LET) spectra on board the Mir orbital station during the period from 8 October 1997 to 16 June 2000, i.e. during the 24th, 26th, 27th and 28th basic expeditions. It was found that the LET spectra of secondary particles between 10 and 700 keV.microm(-1) in tissue do not depend on the external radiator, with the average quality factors for the region mentioned being about 6.4 with ICRP 26 quality factors or about 7.4 with ICRP 60 quality factors. Both differential and integral LET spectra are presented for some typical cases. The spectra permitted us to calculate the total doses and dose equivalents due to particles with the LET values in the mentioned region. It was found that these doses are higher when the detector was placed in a less shielded area. It was also found that these doses vary from one expedition to another. The correlation of these variations with the solar activity level was studied.