Instrumentation for investigation of the depth-dose distribution by the Liulin-5 instrument of a human phantom on the Russian segment of ISS for estimation of the radiation risk during long term space flights.

Described is the Liulin-5 experiment and instrumentation, developed for investigation of the space radiation doses depth distribution in a human phantom on the Russian Segment of the International Space Station (ISS). Liulin-5 experiment is a part of the international project MATROSHKA-R on ISS. The experiment MATROSHKA-R is aimed to study the depth dose distribution at the sites of critical organs of the human body, using models of human body-anthropomorphic and spherical tissue-equivalent phantoms. The aim of Liulin-5 experiment is long term (4-5 years) investigation of the radiation environment dynamics inside the spherical tissue-equivalent phantom, mounted in different places of the Russian Segment of ISS. Energy deposition spectra, linear energy transfer spectra, flux and dose rates for protons and the biologically-relevant heavy ion components of the galactic cosmic radiation will be measured simultaneously with near real time resolution at different depths of the phantom by a telescope of silicon detectors. Data obtained together with data from other active and passive dosimeters will be used to estimate the radiation risk to the crewmembers, verify the models of radiation environment in low Earth orbit, validate body transport model and correlate organ level dose to skin dose. Presented are the test results of the prototype unit. The spherical phantom will be flown on the ISS in 2004 year and Liulin-5 experiment is planned for 2005 year.     

Utilization of white potatoes in CELSS.

Potatoes (Solanum tuberosum) have a strong potential as a useful crop species in a functioning CELSS. The cultivar Denali has produced 37.5 g m-2 d-1 when grown for 132 days with the first 40 days under a 12-h photoperiod and a light:dark temperature cycle of 20 degrees C:16 degrees C, and then 92 days under continuous irradiance and a temperature of 16 degrees C. Irradiance was at 725 micromoles m-2 s-1 PPF and carbon dioxide at 1000 micromoles mol-1. The dried tubers had 82% carbohydrates, 9% protein and 0.6% fat. Other studies have shown that carbon dioxide supplementation (1000 micromoles mol-1) is of significant benefit under 12-h irradiance but less benefit under 24 h irradiance. Irradiance cycles of 60 minutes light and 30 minutes dark caused a reduction of more than 50% in tuber weight compared to cycles of 16 h light and 8 h dark. A diurnal temperature change of 22 degrees C for the 12-h light period to 14 degrees C during the 12-h dark period gave increased yields of 30% and 10% for two separate cultivars, compared with plants grown under a constant 18 degrees C temperature. Cultivar screening under continuous irradiance and elevated temperatures (28 degrees C) for 8 weeks of growth indicated that the cvs Haig, Denali, Atlantic, Desiree and Rutt had the best potential for tolerance to these conditions. Harvesting of tubers from plants at weekly intervals, beginning at 8 weeks after planting, did not increase yield over a single final harvest. Spacing of plants on 0.055 centers produced greater yield per m2 than spacing at 0.11 or 0.22 m2. Plants maintained 0.33 meters apart (0.111 m2 per plant) in beds produced the same yields when separated by dividers in the root matrix as when no separation was made.     

The effect of cannibalism intensity on net primary production and dynamics of trophic links in aquatic ecosystems.

A mathematical model was used to investigate the effect of cannibalism intensity on the net primary production and the dynamics of trophic links in an aquatic ecosystem characterized by cannibalism at the upper trophic level. A mathematical model of an aquatic ecosystem has been constructed, with the following principal trophic links: limiting nutrient concentration, producers (phytoplankton), nonpredatory and predatory zooplankton. The model takes into account the age structure of the predator and includes two age groups (the young and adults). The adult predators are cannibals feeding on both nonpredatory zooplankton and their own young, which consume phytoplankton. It has been found that when cannibalism intensity increases above a certain level, the concentrations of both adults and the young of the predators decrease. At the same time, the concentrations of the nonpredatory zooplankton and of nutrients increase, while the biomass of producers decreases. When the cannibalism intensity is low, the net primary production of the system increases to a certain level correlated with the increase in cannibalism intensity and drops sharply when the level of consumption of young is high. There is an optimal intensity of cannibalism, at which the productivity in the photosynthesis link is maximal.     

The role of repair in the survival of mammalian cells from heavy ion irradiation: approximation to the ideal case of target theory.

Theories of cellular radiation sensitivity that preclude a significant role for cellular repair processes in the final biological expression of cellular damage induced by ionizing radiation are unsound. Experiments are discussed here in which the cell-cycle dependency of the repair deficiency of the S/S variant, of the L5178Y murine leukemic lymphoblast was examined by treatment with the heavy ions, 20Ne, 28Si, 40Ar, 56Fe and 93Nb. Evidence from those studies, which will be described in detail elsewhere, provide support for the notion that as the linear energy transfer (LET infinity) of the incident radiation increases the ability of the S/S cell to repair radiation damage decreases until effectively it is eliminated around 500 keV/micrometer. In the region of the latter LET infinity value, the behavior of the S/S cell approximates the ideal case of target theory where post-irradiation metabolism (repair) does not influence cell survival. The expression of this phenomenon among different cell types and tissues will depend upon the actual repair systems involved and other considerations.     

Volatile metabolites of higher plant crops as a photosynthesizing life support system component under temperature stress at different light intensities.

The effect of elevated temperatures of 35 and 45 degrees C (at the intensities of photosynthetically active radiation 322, 690 and 1104 micromoles m-2 s-1) on the photosynthesis, respiration, and qualitative and quantitative composition of the volatiles emitted by wheat (Triticum aestuvi L., cultivar 232) crops was investigated in growth chambers. Identification and quantification of more than 20 volatile compounds (terpenoids--alpha-pinene, delta 3 carene, limonene, benzene, alpha- and trans-caryophyllene, alpha- and gamma-terpinene, their derivatives, aromatic hydrocarbons, etc.) were conducted by gas chromatograph/mass spectrometry. Under light intensity of 1104 micromoles m-2 s-1 heat resistance of photosynthesis and respiration increased at 35 degrees C and decreased at 45 degrees C. The action of elevated temperatures brought about variations in the rate and direction of the synthesis of volatile metabolites. The emission of volatile compounds was the greatest under a reduced irradiation of 322 micromoles m-2 s-1 and the smallest under 1104 micromoles m-2 s-1 at 35 degrees C. During the repair period, the contents and proportions of volatile compounds were different from their initial values, too. The degree of disruption and the following recovery of the functional state depended on the light intensity during the exposure to elevated temperatures. The investigation of the atmosphere of the growth chamber without plants has revealed the substances that were definitely technogenic in origin: tetramethylurea, dimethylsulfide, dibutylsulfide, dibutylphthalate, and a number of components of furan and silane nature.     

New model of hair cell bundle functioning in otoliths.

Transformation of the mechanical input in the chain: acceleration of otolithic membrane (OM)-displacement of the OM gel layer -deflection of hair cell bundle (HCB) -deformation of the system of tip-links- formation of temporal pattern of polarization was studied using simplified analytical models of these stages of conversion of mechanical stimulus into the HCB electrical response. The process of transformation of information in this chain was considered for two extreme cases of OM gel-HCB interaction: 1) the HCBs exactly follow the gel displacement; 2) stiff stereocilia and weak surrounding gel allow the relative motion of the bundle with regard to the gel. The analysis of a simplified model of cell polarization based on threshold triggering of the HCB tip-links allows to hypothesize that spatially nonhomogeneous HCB structure with a set of stereocilia of varying heights is designed to perceive spatially nonhomogeneous gel displacements caused by external acceleration. Thus, the HCB-OM gel interaction in the first case leads to formation of temporal pattern of depolarization that corresponds to the temporal pattern of gel displacement. In the second case the kinetics of depolarization reflects time dependence of gel displacement velocity.     

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.     

Fiber-optic gyros and quartz accelerometers for motion control

In article the opportunity of use strapdown inertial navigation system (SINS) on the base of fiber-optic gyroscopes and quartz accelerometers corrected from star sensors and satellite navigation equipment (SNE) for perspective interplanetary spacecrafts motion control on phases of interplanetary trajectory insertion, trajectory correction, and braking during transition to Mars orbit is investigated. Results of onboard control complex accuracy characteristics estimation are presented at the given dynamic spacecraft scheme which is taking into account the liquid oscillations in tanks and structure elements elasticity. At modelling the errors of measuring devices installation, errors of SINS initial alignment and instrumental errors of SINS sensitive elements, variation of control engines parameters were taken into account. The structure of the developed complex of imitation modelling of interplanetary spacecraft controlled motion is resulted. Estimations of active flight legs realization accuracy were received by a method of statistical modelling of spacecraft controlled motion     

Coordinated Continual Planning Methods for Cooperating Rovers

Eight evaluation metrics are used to compare and contrast three coordination schemes for a system that continuously plans to control collections of rovers (or spacecraft) using collective mission goals instead of goals or command sequences for each spacecraft. These schemes use a central coordinator to either: 1) micromanage rovers one activity at a time; 2) assign mission goals to rovers; or 3) arbitrate mission goal auctions among rovers. A self-commanding collection of rovers would autonomously coordinate itself to satisfy high-level science and engineering goals in a changing partially understood environment - making the operation of tens or even a hundred spacecraft feasible