Some Features of Vibrational Perturbations onboard the MirOrbital Station

A number of scientific and technical experiments were carried out and are still being carried out onboard the Mirorbital station in various fields: physics of fluids, space materials study, astrophysics, biotechnology, and so on. The quality and reliability of space experiments are essentially dependent on a knowledge of real microgravitational situation onboard a satellite, which essentially depends on vibrational perturbations. A lot of vibration processes studies have been done up to now on the Mirstation in the following lines of research: control of dynamic and exploitation regimes when carrying out biotechnological and technological experiments; determination of the contribution of different onboard systems and mechanisms to the total vibration perturbations power; and investigation of distributions of microacceleration levels and dynamics of vibration processes in different modules and segments of the orbital station. This paper presents the results of the analysis of vibration perturbations produced by some standard onboard Mirstation systems in a configuration when the KVANT-2 and KRISTALL modules were arranged along the yaw axis of the mainframe. It is shown that due to strong requirements for tolerable levels of the microaccelerations onboard the International Space Station (ISS), the investigations of microgravitational situation, as an integral part of the technological environment, now have a high priority.     

Experimental Study of the Structures of Macroparticles in the Dust Plasma under Microgravity Conditions onboard the MirOrbital Complex

The dynamics of formation of the ordered structures of charged macroparticles under microgravity conditions is investigated. The experimental observations of the behavior of an ensemble of macroparticles were carried out onboard the Mirspace station. The analysis and comparison of results of experimental and theoretical investigations allow us to conclude that under microgravity conditions the formation of elongated, ordered structures of macroparticles, charged by solar radiation, is possible.     

The Production of Biologically Active Substances by Plant Cell Cultures in Space

The impact of the conditions of space flight on the productivity of cultures of the plant cells with respect to the biomass and the metabolites is investigated. The experiments were performed with the callus cultures of the cells of ginseng (Panax ginseng), red root puccoon (Lithospermum arythrorhizon), and macrotomia coloring (Macrotomia euchroma) onboard the orbital station Mirand American Space Shuttle. A more pronounced variation of the output of the metabolites is noted with respect to the ground control. This output depends upon the properties of the strain and conditions of the experiment.     

Large proton disturbances in the orbit: 14 years later

A comparison of the measurement data of radiation conditions onboard the ISS during solar proton events in October 2003 and onboard the Mir orbital station in October 1989 is carried out. It is shown that there is a difference in the conditions of particle penetration to the station orbits during these series of flares. Computational estimates of the absorbed doses are obtained, and they agree well with the data of measurements by standard instruments of radiation monitoring. The comparisons made demonstrate that the equivalent thickness of the shield at the location of the R-16 radiometer onboard the ISS exceeds the corresponding value onboard the Mir station by a factor of 2.8.Translated from Kosmicheskie Issledovaniya, Vol. 42, No. 6, 2004, pp. 663–667.Original Russian Text Copyright © 2004 by Bondarenko, Mitrikas, Tsetlin.     

Transport Characteristics of Macroparticles in Dusty Plasma Induced by Solar Radiation under Microgravity Conditions

The transport characteristics of macroparticles, charged by the solar radiation under microgravity conditions, were investigated by analyzing the videorecords of experiments carried out onboard the Mirorbital station. The temperature, distributions of velocities, charge, friction coefficient, and diffusion coefficient were obtained for bronze particles.     

Influence of Basic Sources of Disturbances on Microgravity Conditions in the MirStation Modules as Estimated from the Data of the SAMS and MASU Instruments

The influence of basic sources of disturbances on microgravity conditions in the modules of the Mirorbital station is estimated. The onboard air compressor, gyrodynes, and the crew activity are among these sources. The data of measurements made with the SAMS and MASU instruments in 1996–1997 are used.     

Influence of simulated and natural space environment factors on dielectric properties of epoxyamine polymers and polymer-based composite materials

The variations of dielectric properties of epoxyamine polymers and polymer-based composite materials during ground-based tests imitating the influence of space environment factors and under the conditions of long-term active experiments using the ERE instrumentation onboard the Mir station are compared. The influence of space environment factors is shown to result in both reversible and irreversible changes of dielectric properties. The former are related to temperature effects and effects of charged particles. The latter are related to the removal of low-molecular components from the composition of binders in a vacuum, and to increasing density of polymeric lattice under an effect of thermal cycling and various types of radiations. It is established that the influence of ultra-violet radiation reveals itself, first of all, in changing temperature of samples, while the influence of irradiation by a flux of electrons is reduced to charge accumulation and discharges.Translated from Kosmicheskie Issledovaniya, Vol. 43, No. 1, 2005, pp. 27–35.Original Russian Text Copyright © 2005 by Babaevsky, Kozlov, Churilo, Slagoda.     

Effect of Microaccelerations on the Distribution of a Dopant in a Semiconductor Melt during Space Flight

The effect of residual microaccelerations on the distribution of a dopant in a semiconductor melt located in a heated closed cavity onboard an Earth-orbiting satellite is considered in the context of a model problem of thermal convection. The amplitude–frequency characteristics of the response of this distribution to the perturbing microaccelerations are obtained. It is demonstrated that the effect of low-frequency microaccelerations decreases when the frequency increases. A comparison is made of the macroscopic inhomogeneities of the dopant concentration due to the actual low-frequency (quasi-static) component of microaccelerations onboard different spacecraft: the orbital station Mir, the satellite Foton-11, a Space Shuttle orbiter, and the International Space Station. A substantial effect of the rotational motion of the spacecraft on the character of the time behavior of a macroscopic inhomogeneity is demonstrated.     

Influence of Microgravity on Self-Propagating High-Temperature Synthesis of Refractory Inorganic Compounds

The self-propagating high-temperature synthesis was applied for the production of foam materials under the conditions of microgravity aboard the Mirstation. The materials obtained have a porous bimodal structure. The results of space experiments predicted using the interpolation method are checked. An unpredicted phase separation of the combustion products is discovered. The autowave combustion of suspended nickel-clad aluminum solids is observed for the first time. The combustion products were found to have a frame structure.     

Investigation of Thermal Convection and Low-Frequency Microgravity by the DACON Sensor aboard the MirOrbital Complex

The DACON instrument for studying the convection caused by low frequency microaccelerations aboard spacecraft is described. The convection sensor serves as a measuring element of this instrument. This is a cylindrical cavity filled with air, where two crossed differential thermocouples are located. The thermocouple junctions lay on two mutually perpendicular lines parallel to the bases of the cylinder and crossing at its axis. The distances from the junctions to this axis are equal. The lateral surface of the cylinder is thermally insulated, the difference of temperatures on its bases being kept constant. One of the tasks for the sensor is to prepare the data for checking the adequacy of mathematical models of fluid convection under weightlessness conditions and for obtaining quantitative characteristics of the microgravitational medium. The results of ground-based tests of the DACON instrument and the results of experiments with it aboard the Mirstation are presented.     

Measurement of the Quasistatic Component of Microaccelerations Using a Convection Sensor onboard a Satellite

The problem of the interpretation of measurements made by means of a convection sensor is considered. The sensor is a cubic chamber filled by a viscous fluid (gas). Fixed and unequal temperatures are maintained on two opposite sides of the cube; the other sides are perfect heat conductors. Two differential thermocouples are placed inside the chamber to measure the temperature difference at two pairs of fixed points. The sensor is mounted aboard the Earth's satellite. Mathematical models of various degrees of complexity are proposed which describe processes of heat and mass transfer under the action of a quasistatic component of microaccelerations. The results of mathematical simulation of the data of sensor thermocouples presenting a response to the real quasistatic component of microaccelerations which took place aboard the Mirstation are given. It is shown that under usual conditions of an orbital mission the sensor presents a linear low-frequency filter. By combining the data of several identical sensors, tightly arranged and oriented in a certain way, it is possible to measure low-frequency components of the angular acceleration of the satellite and linear microaccelerations at the point of the sensor position.     

Near-Equatorial Electrons as Measured onboard the MirSpace Station

Some results of studying the electrons with energies of tens to hundreds of keV at the low and near- equatorial geomagnetic latitudes by using the instruments Sprut-V and Ryabina-2 onboard the Mirspace station in 1991 are presented. It is found that at L< 1.2 the enhanced electron fluxes are sporadically detected, being localized within three longitudinal intervals, 180° W–0°–15° E, 90°– 120° E, and 160° E–180°–135° W. The most intense electron fluxes are observed at the lower edge of the near-equatorial boundary of the inner radiation belt on longitudes of the South Atlantic Anomaly between 14 and 20 h MLT. The occurrence of electron bursts does not depend on the geomagnetic disturbance level. A hardening of the electron spectra is observed near the geomagnetic equator. At L< 1.1, the more energetic particles are located closer to the geomagnetic equator. The results are compared with the data on the low-frequency waves and fields at low and near-equatorial latitudes obtained by the Ariel-4and San Marco Dsatellites, as well as by the spacecraft and ground-based observations of the thunderstorm global distribution. The thunderstorms are considered as a possible source of electron production near the geomagnetic equator.     

Mechanics of Zero Gravity and Gravitationally Sensitive Systems (First Issue)

This issue of the journal contains papers with the results of studying gravitationally sensitive systems and processes under conditions of microgravity aboard the Mirorbital complex. This is one of the most difficult field of space research whose difficulties are due to both complexity of the object of investigations (since the class of gravitationally sensitive systems and processes is fairly wide, and some of them are not sufficiently studied even under terrestrial conditions) and necessity of using expensive instrumentation and carrying out long-term experiments. However, studying the new mechanical state of weightlessness is inevitable in space exploration. In addition, in some cases it can provide for a new knowledge about the fundamental laws of nature. By virtue of the above reasons, the experiments on microgravity are well presented in the research program onboard the International Space Station.There is a long tradition in this field of research in Russia, and the experience of Russian scientists (a part of which is presented in the papers of this issue) allows them to pass on to the next, better technically equipped, stage of investigations in cooperation with the scientists from other countries.This issue is prepared by an initiative of the subsection Mechanics of zero gravity and gravitationally sensitive systemsof the Coordination Scientific and Technical Council (CSTC) of the Russian Agency for Aviation and Space Flights (Rosaviakosmos).     

Uncontrollable Rotational Motion of the Mir Orbital Station

The results of determining the rotational motion of the Mir orbital station are presented for four long segments of its unmanned uncontrolled flight in 1999–2000. The determination was carried out using the data of onboard measurements of the Earth's magnetic field intensity. These data, taken for a time interval of several hours, were jointly processed by the least squares method with the help of integration of the equations of station motion relative to its center of mass. As a result of this processing, the initial conditions of motion and the parameters of the mathematical model used were evaluated. The technique of processing is verified using the telemetry data on angular velocity of the station and its attitude parameters. Two types of motion were applied on the investigated segments. One of them (three segments) presents a rotation around the axis of the minimum moment of inertia. This axis executes small oscillations with respect to a normal to the orbit plane. Such a motion was used for the first time on domestic manned orbital complexes. The second type of motion begins with a biaxial rotation which, in a few weeks, goes over into a motion very similar to the rotation around the normal to the orbit plane, but around the axis of the maximum moment of inertia.     

Detection and Prediction of Absorbed Radiation Doses from Solar Proton Fluxes onboard Orbital Stations

We consider cases of simultaneous detection of the absorbed doses produced by proton fluxes of powerful solar events onboard the Mir and ISS orbital stations and the Ekspress A3 geosynchronous satellite. Experimental data are analyzed using a software package that takes into account the energy spectra of protons at the Earth's orbit depending on the time of event evolution, as well as their penetration to near-earth orbits and through the protective shields of spacecraft. Based on a comparison of the experimental data of dosimeters with the calculation of absorbed doses under the action of solar proton events, we developed a method of estimating the effective thickness of the shielding of dosimeters and made some estimates. A possibility is considered for predicting the radiation hazard onboard orbital stations upon the appearance of solar proton events using dosimeter data from a geosynchronous orbit.     

One Possible Mechanism to Sustain Combustion inside a Closed Region under Zero Gravity

An experimental study carried out aboard the Mirstation showed that a stearin candle can burn for a long time even inside a closed volume without a forced circulation. Such experiments imply that there is some mechanism for a permanent transport of the oxidizer to the flame zone. It can be assumed that a jet of combustion products outflowing along a normal direction with respect to the flame surface produces a vortex motion in the environmental space, which delivers oxygen to the flame zone. To verify the feasibility of combustion to be sustained by such a mechanism, a mathematical statement of the problem of combustion inside a closed region under zero gravity without a forced circulation was formulated. A simplified model was put forward to simulate the combustion of solid and liquid substances, which allowed the effects of chemical reactions to be reduced to boundary conditions. The computations showed that the proposed mechanism of oxygen transport to the flame zone really can sustain an almost stationary regime of combustion.     

Ensuring of long operation life of the orbiting station EVA space suit

Russia has gained a lot of experience in operating the space suits (SS) during the extravehicular activities (EVA) by the crews of SALYUT-6, SALYUT-7 and MIR orbiting stations. A total of 21 Orlan-type space suits of various models were operated onboard the orbiting stations (OS) during almost 20 years period. Some of these space suits served up to 3 years in orbit. The paper reviews special features of long SS operation (without return to the Earth) onboard an orbiting station as well as the problems associated with SS repeated use by several crews. An analysis of measures to support solving of the problems of SS long stay and reliable operation onboard the orbiting station is made: selection of a corresponding SS type and separate elements design; selection of the materials; routine and preventive maintenance; development tests. The advantages of the space suit of a semi-rigid type for solving the above problems are shown. The paper includes a short analysis of space suits' operation onboard the Russian orbiting station MIR, and some restuts of inspection of the Orlan-DMA space suit returned to the Earth from orbit by STS-79 alter long operation in orbit. Recommendations on further improvement of the space suits for EVA operations in the International Space Station (ISS) are given.     

Fluxes of Quasi-trapped Electrons with Energies >0.08 MeV in the Near-Earth Space on Drift Shells <Emphasis Type="Italic">L</Emphasis> < 2

We study the characteristics of fluxes of electrons with energy >80 keV in the near-Earth space regions corresponding to the drift shells L = 1.7, 1.4, and 1.1 observed during the entire period of the GRIF experiment onboard the Spectr module of the Mir orbital station from October 1995 to June 1997. The obtained geographic maps of the distribution of electron fluxes at the height of the station flight (400 km) and, also, the estimates of the spectra indicate that the South-Atlantic Anomaly provides for a mechanism of stable replenishment for shells with L < 1.5. The mechanism of stable replenishment of shells with L < 1.5 may be due to the scattering, in the residual atmosphere, of electrons from the inner radiation belt precipitating into the region of the South-Atlantic Anomaly.