Natural killer cells after ALTAIR mission

Reduced in vitro NK cytotoxic activity have routinely been observed after both prolonged and short-term space flights. This study investigated the effects of space flight on NK cell functions, NK cell counts and the production of IL-2 and TNF by lymphocytes of French-Russian crew members. In the French cosmonaut, after 21 days space flight, the cytotoxic activity of NK cells, the capacity the NK cells to bind and lyse the individual target cells and the percentage of NK cells were decreased. In this cosmonaut a twofold reduction TNF production in cultures of lymphocytes stimulated with PMA and with the mixture of PHA and PMA was observed on the first day after landing. However, the activity of the production of TNF in 48-hour PHA-cultures of lymphocytes was unchanged and the biological activity of IL-2 was not reduced. The immunological examination did not detecte any substantial deviations from the norm in both russian cosmonauts after 197 days space flight. Various explanations for decreased cytotoxicity in cosmonauts after space flight can be proposed, and these include the defective function of NK cells and reduced numbers of circulating effector cells.     

Coronal loops and prominences as observed with RATAN-600

This paper presents a short summary of observations of coronal structures at microwaves using an instrument with high spatial resolution and good wavelength coverage. The comparison of the RATAN-600 data with optical observations of coronal loops in the green line and with the Very Large Array maps at 21 cm has shown that the loops represent only a small part of coronal matter, although their role may be of great importance in the physics of the solar corona. Prominence (filament) associated sources, especially peculiar ones, are also reviewed.     

"From seed-to-seed" experiment with wheat plants under space-flight conditions.

An important goal with plant experiments in microgravity is to achieve a complete life cycle, the "seed-to-seed experiment." Some Soviet attempts to reach this goal are described, notably an experiment with the tiny mustard, Arabidopsis thaliana, in the Phyton 3 device on Salyut 7. Normal seeds were produced although yields were reduced and development was delayed. Several other experiments have shown abnormalities in plants grown in space. In recent work, plants of wheat (Triticum aestivum) were studied on the ground and then in a preliminary experiment in space. Biometric indices of vegetative space plants were 2 to 2.5 times lower than those of controls, levels of chlorophyll a and b were reduced (no change in the ratio of the two pigments), carotenoids were reduced, there was a serious imbalance in major minerals, and membrane lipids were reduced (no obvious change in lipid patterns). Following the preliminary studies, an attempt was made with the Svetoblock-M growth unit to grow a super-dwarf wheat cultivar through a life cycle. The experiment lasted 167 d on Mir. Growth halted from about day 40 to day 100, when new shoots appeared. Three heads had appeared in the boot (surrounded by leaves) when plants were returned to earth. One head was sterile, but 28 seeds matured on earth, and most of these have since produced normal plants and seeds. In principle, a seed-to-seed experiment with wheat should be successful in microgravity.     

Design to safety: experience and plans of the Russian space suit programme

The paper presents the analysis of the Russian experience gained in the operations of Salyut-6, 7 and Mir orbital stations. The main factors determining their effectiveness and safety are considered and the main requirements to the EVA suit, as the most important tool for the EVA, are formulated.     

Efficacy of periodic centrifugation of primates during 4-week head-down tilt.

Creation of artificial force of gravity (AFG) to counteract the negative consequences of microgravity in manned space missions of extended duration is one of the high-priority problems of space biology and medicine. However, there are a number of especial effects of AFG (namely, structural changes in muscles and bones, and some other system) which need implantation of electrodes and sensors and are possible only with animals. That is why it is of particular interest to make studies with monkeys whose reactions to changed gravity bear much resemblance with human. The purpose of the investigation was development of a protocol of periodic gravity loads as a counter-measure against the hypokinetic syndrome in Macaca mulatta. Two series of experiments were performed. In the series, animals were split into two groups of 6 species each who were motor restrained with the head end tilted downward at 5 degrees (HDT) for 28 days. Monkeys of group-2 were periodically subjected to centrifugation (HDT+G). During the first series of experiments rotation was conducted in the +Gz direction at g-loads from 1.2 to 1.6 units for 30-40 minutes 4-5 times a week. In the second series, g-load was equal to 1.2 units and the animals were rotated 30 min. 2-3 time a week. The criterion of Y-training protocol efficacy was a test +Gz run at 3 units for 30 s. during which functioning of the cardiovascular systems and its controls was evaluated. The test run was performed prior to and after HDT. Following HDT the animals of group HDT+G were more resistant to the test than their counterparts who had not been trained on the centrifuge. Data of the investigation imply that following HDT and HDT+G alike reduced the amount of total bodily fluids (by approximately 5%), the intracellular component (approximately 4%), and plasma volume (by 6-7%). Yet, there are radical differences between the groups in the levels of reduction in extracellular fluids (by 11% and 6.5%, respectively, P<0.05) and the interstitial component (by 11.5% and 6.5, respectively, P<0.05). Prophylactic centrifugation during HDT was also positive to the muscular blood flow in lower extremities.     

Plasma and urine catecholamine levels in cosmonauts during long-term stay on Space Station Salyut-7.

The activity of the sympathetic adrenal system in cosmonauts exposed to a stay in space lasting for about half a year has so far been studied only by measuring catecholamine levels in plasma and urine samples taken before space flight and after landing. The device "Plasma 01", specially designed for collecting and processing venous blood from subjects during space flight on board the station Salyut-7 rendered it possible for the first time to collect and freeze samples of blood from cosmonauts in the course of a long-term 237-day space flight. A physician-cosmonaut collected samples of blood and urine from two cosmonauts over the period of days 217-219 of their stay in space. The samples were transported to Earth frozen. As indicators of the sympathetic adrenal system activity, plasma and urine concentrations of epinephrine and norepinephrine as well as urine levels of the catecholamine metabolites metanephrine, normetanephrine, and vanillylmandelic acid were determined before, during and after space flight. On days 217-219 of space flight plasma epinephrine and norepinephrine levels were slightly increased, yet not substantially different from normal. During stress situations plasma norepinephrine and epinephrine levels usually exhibit a manifold increase. On days 217-219 of space flight norepinephrine and epinephrine levels in urine were comparable with pre-flight values and the levels of their metabolites were even significantly decreased. All the parameters studied, particularly plasma norepinephrine as well as urine norepinephrine, normetanephrine, and vanillylmandelic acid, reached the highest values 8 days after landing. The results obtained suggest that, in the period of days 217-219 of the cosmonauts stay in space in the state of weightlessness, the sympathetic adrenal system is either not activated at all or there is but a slight activation induced by specific activities of the cosmonauts, whereas in the process of re-adaptation after space flight on Earth this system is considerably more markedly activated.     

Continuum Model for Space Debris Evolution with Account of Collisions and Orbital Breakups

The paper discusses the mathematical modeling of long-term orbital debris evolution taking into account mutual collisions of space debris particles of different sizes. Investigations and long-term forecasts of orbital debris environment evolution in low Earth orbits are essential for future space mission hazard evaluation and for adopting rational space policies and mitigation measures. The paper introduces a new approach to space debris evolution mathematical modeling based on continuum mechanics incorporating partial differential equations. This is an alternative to the traditional approaches of celestial mechanics incorporating ordinary differential equations to model fragments evolution. The continuum approach to orbital debris evolution modeling has essential advantages for describing the evolution of a large number of particles, because it replaces the traditional tracking of space objects by modeling the evolution of their density of distribution.     

Microgravity measurement assembly (MMA) for spacelab module missions

The microgravity measurement assembly (MMA) is a precision measurement facility for ground and on-orbit disturbance accelerations on board Spacelab, being currently under development by MBB/ERNO under DFVLR contract. MMA is using a new generation of micromechanical acceleration detectors developed by CSEM under ESTEC contract. Small dimensions of the triaxial sensor packages allow for installation very close to scientific experiments; mass is significantly reduced compared to conventional systems. Six or more of these mini-sensor packages are installed at the most g-sensitive experiments of Spacelab Module Missions. Acceleration and housekeeping data are processed in real time by a dedicated microcomputer and transmitted to the ground. Thus, for the first time, synchronized and comparable precision acceleration data are available in real time on ground for on-line judgement of the microgravity environment desired for experiment success, offering the possibility, for example of experiment repetition in case of excessive g-disturbances. Furthermore, MMA allows for immediate feedback to the crew concerning the microgravity effects of their dynamic behavior, with the aim of crew training towards lower disturbances. An additional mobile sensor package can be installed at vibration sources, e.g. pumps, centrifuges etc. or any arbitrary location inside the Spacelab Module. An impact hammer can be used together with MMA in order to measure in-flight structural transfer functions. The MMA on-board system and ground station and its planned utilization for the German Spacelab Mission D-2 is described.