Laboratory experiments and space phenomena

Two types of convection were observed in the laboratory model of the magnetosphere: viscous convection and convection due to field lines common to both the magnetosphere and artificial solar wind. With a southward field component in the solar wind, convection from the Sun is observed in the polar cap, while with a large northward component, convection is directed toward the Sun. Merging of the field lines occurs in the cleft. With the southward component, a visor appears in front of the magnetosphere boundary. The decay of the visor into small magnetic structure is observed. The formation of an induced magnetosphere with a magnetic tail is shown in the experiments of the simulated conditions near non-magnetic bodies with a plasma shell (Venus, comets). A combined induced-intrinsic magnetosphere also was investigated.     

Accommodations for earth-viewing payloads on the international space station

The design of the International Space Station (ISS) includes payload locations that are external to the pressurized environment. These external or attached payload accommodation locations will allow direct access to the space environment at the ISS orbit and direct viewing of the earth and space. NASA sponsored payloads will have access to several different types of standard external locations; the S3 Truss Sites, the Columbus External Payload Facility (EPF), and the Japanese Experiment Module Exposed Facility (JEM-EF). As the ISS Program develops, it may also be possible to locate external payloads at the P3 Truss Sites or at non-standard locations similar to the handrail-attached payloads that were flown during the MIR Program. Earth-viewing payloads may also be located within the pressurized volume of the US Lab in the Window Observational Research Facility (WORF). Payload accommodations at each of the locations will be described, as well as transport to and retrieval from the site.     

The effect of neglecting VLBI reference station clock offsets on UT1 estimates

Very Long Baseline Interferometry (VLBI) allows to monitor universal time (UT1) by conducting regular international experiments. Such dedicated observation networks are equipped with different hardware components, which require different processing strategies when the data are correlated. As the timing units at each stations are usually offset with respect to universal time (UTC) this effect should be considered during correlation processing. Thus, it is investigated how neglecting of these offsets theoretically impacts the estimation of UT1. Three different strategies for the proper handling of the timing offset will be discussed and their advantages/drawbacks will be pointed out. Moreover, it is studied how neglecting of these timing offsets affects UT1 time-series and how such a missing correction can be applied a posteriori. Although the discussed effect is for most of the UT1 experiments smaller than the formal error of the estimates, it is important to consider station clock offsets properly in next-generation VLBI systems, which are expected to improve accuracy of results by about one order of magnitude.     

Planned NASA space infrared astronomy experiments

A summary is presented of the present status of the NASA space infrared astronomy program. Projects described include the Infrared Astronomy Satellite (IRAS), Small Infrared Telescope on Spacelab 2 (IRT), Cosmic Background Explorer (COBE), Shuttle Infrared Telescope Facility (SIRTF), Space Telescope (ST), and the Large Deployable Reflector (LDR). The important technical developments achieved in these programs are also discussed, as well as critical needs for future missions.     

Prospects in instrumentation for future space experiments

The wealth of observational material provided by the COS-B and SAS-2 telescopes has provided a great incentive to develop new and better techniques for high energy gamma-ray astronomy. The prospects of achieving a greater sensitivity and a much improved angular resolution in future gamma-ray telescopes are reviewed in the light of the predicted performance of payloads already approved and new techniques being developed in the laboratory.     

Cosmic dust and orbital debris: Collection on MIR space station

Upon the last joint Soviet-French mission on the MIR Space Station, on December 1988, an experiment devoted to the collection and detection of cosmic dust and space debris has been deployed in space during 13 months.

A variety of sensors and collecting devices has make possible the study of effects and distribution of cosmic particles after recovery of exposed material. Remnants of particles, suitable for chemical identification are expected to be found within the stacked foil detectors. Discrimination between true cosmic particles and man-made orbital debris is expected.

Some preliminary results are presented here.     

Heavy particle fluxes in Salyut space station orbit

Results of a detailed analysis of heavy ion fluences measured on the Salyut and MIR orbital stations from 1978 to 1990 are presented. The analysis has made use of new models that describe the cosmic ray fluxes and their transition through the magnetosphere. The penetration of solar cosmic ray particles to the orbit, the increase of the (ScCr)/Fe flux ratio in the orbit, and the occurrences of 200–500 MeV/nucl heavy nuclei in <30° latitudes have been analyzed.     

Large-size space laboratory for biological orbit experiments.

The study of space factors on living systems has great interest and long-term experiments during orbital flight will be important tool for increasing our knowledge. Realization of such experiments is limited by constraints of modern space stations. A new technology of large-size space laboratory for biological experiments has been developed on the basis of polymerization techniques. Using this technique there are no limits of form and size of laboratory for a space station that will permit long term experiments on Earth orbit with plants and animals in sufficient volume for creation of closed self-regulating ecological systems. The technology is based on experiments of the behavior of polymer materials in simulated free space conditions during the reaction of polymerization. The influences of space vacuum, sharp temperature changes and space plasma generated by galactic rays and Sun irradiation on chemical reaction were evaluated in their impact on liquid organic materials in laboratory conditions. The results of our study shows, that the chemical reaction is sensitive to such space factors. But we believe that the technology of polymerization could be used for the creation of space biological laboratories in Earth orbit in the near future.     

发展我国的空间用高准确度原子钟

原子钟在科学技术、军事和商业中应用甚广,在空间任务,特别是卫星导航系统中起着决定性作用。目前我国还没有自己的空间用高准确度原子频标,发展适合空间应用的星载原子钟是我们面临的迫切任务。     

Microgravity particle research on the space station: the Gas-Grain Simulation Facility.

In the gravitational field on Earth, the large settling rate of micron-sized particles and the effects of gravity-induced convection prohibit many interesting studies of phenomena such as coagulation, collisions, and mutual interactions of droplets, dust grains and other particles. Examples of exobiology experiments involving these phenomena are the simulation of organic aerosol formation in Titan's atmosphere, studies of the role of comets in prebiotic chemical evolution, and simulations of carbon grain interactions in various astrophysical environments. The Gas-Grain Simulation Facility (GGSF) is a proposed Earth-orbital laboratory that will allow present ground-based experimental programs which study processes involving small particles and weak interactions to be extended to a new domain. Physics issues that scientists wishing to propose GGSF experiments must consider are reviewed in this paper. Specifically, coagulation, motion in gases and vacua, and wall deposition of particles in a microgravity environment are discussed.     

Telescience testbed for biomedical experiments in space morphological and physiological experiments of rat musculoskeletal system.

As the second telescience testbed experiment we were examined sophisticated processes of biomedical experiment, such as an implantation of a transmitter into the hamster's abdominal cavity, non-stressful blood sampling, large amount of blood collection, muscle extirpation and biopsy from the hamsters on February 6-8, 1990. To make clear the differences between successful results obtained by an experienced hand and by a non-experienced one, three operators were selected for three successive experimental days; an engineer who had never experienced any biological experiment, a non-biology student, who experienced on biological experiments, and a veterinary surgeon. Surgical procedures need much experiences on maneuvering and understanding of theory to shorten the elapse time. Especially for a non-experienced hand, graphic instructions were much helpful to understand and to maneuver the procedures. Continuous recordings of ECG from a operator and PIs were of an advantage to grasp an extent of the mental strain, which was compared with their reports requested after end of each experimental day. The mental strain was not related to degrees of scientific achievement, but showed faithfully difficulty of each experimental procedure. Training effects on PIs in successive experimental days were found in their instructions for the operator to let understand the procedures.     

Study of the radiation environment on MIR space station with SILEYE-2 experiment.

In this work we present preliminary results of nuclear composition measurements on board space station MIR obtained with SILEYE-2 particle telescope. SILEYE-2 was placed on MIR in 1997 and has been working since then. It consists of an array of 6 active silicon strip detectors which allow nuclear and energetic identification of cosmic rays in the energy range between approximately 30 and 200 MeV/n. The device is attached to an helmet and connected to an eye mask which shields the cosmonaut eyes from light and allow studies of the Light Flashes (LF) phenomenon. In addition to the study of the causes of LF, the device is used to perform real time long term radiation environment monitoring inside the MIR, performing measurements in solar quiet and active days.     

Planning for the scientific use of the international space station complex

The United States has begun the development of an international Space Station complex in cooperation with Japan, Canada, and the European Space Agency. The planned uses of the facility encompass a broad spectrum of research disciplines including life sciences, material sciences, astrophysics, earth sciences and planetary sciences. Activity has already started on the preparation of scientific proposals, and in some cases on specific pieces of instrumentation, in many of these areas. Long-duration, continuous research in space in a manned facility presents situations, problems and opportunities which have never before needed to be addressed. This paper presents current thinking in the United States on several of these issues related specifically to the microgravity sciences and an initial paradigm for their solution.     

Aquatic animal research in space station and its issues--focus on support technology on nitrate toxicity.

We studied the effects of accumulated nitrate in water on the spawning, hatching and development of medaka using a simple nitrifying filter and a combined filter having both nitrifying and denitrifying capabilities. A nitrate concentration of 100 mg NO3(-)-N/L was clearly of lethal toxicity to fish when they were exposed to nitrate in both adult and the growing phases. A nitrate concentration of 75 mg NO3(-)-N/L reduced the fertilization rate, delayed the hatching time and reduced the hatching rate of the eggs laid by adults and decreased the growth rate of juveniles. In addition, nitrate accumulations as low as 50 mg NO3(-)-N/L remarkably retarded spawning and lowered the number of eggs laid by fish exposed in the juvenile phase. The effects on the reproduction system may be initiated by a low concentration, approximately 30 mg NO3(-)-N/L.     

Mathematical simulation of impurity distribution in space processing experiments with semiconductors

The effect of natural convection in the melt on impurity distribution is investigated by numerical simulation in the case of uniaxial growth of semiconductor crystals at low gravity conditions.     

Transient growth effects during space solidification experiments in a Bridgman configuration

This paper reviews the different mechanisms involved during a Bridgman solidification. It is demonstrated that during a space experiment, due to the lack of time it is not possible to wait for steady states for all the phenomena considered. So a non steady state analysis is needed. Mass and heat transfers are considered as well as kinetics effects. Different coupling effects are emphasized. It is shown that fine measurements during space experiments are needed in order to verify these important transient stages. One kind of possible experiments is proposed to enable us a better understanding of the solidification laws.     

Simulation of cosmic man-made dust effects on space vehicle elements in rocket and laboratory experiments

Institute of Experimental Meteorology initiated investigations of anthropogenic contamination (AC) and its influence on the near-earth environment and orbiting vehicles. These investigations are based on rocket experiments on simulation of the effects of gas-dust fluxes at the rate of 7–8 km/s on vehicle optical elements under real space conditions. The fluxes are generated by rocket-borne explosive generators.     

Simulation experiments of the effect of space environment on bacteriophage and DNA thin films.

The main goal of PUR experiment (phage and uracil response) is to examine and quantify the effect of specific space conditions on nucleic acid models. To achieve this an improved method was elaborated for the preparation of DNA and bacteriophage thin films. The homogeneity of the films was controlled by UV spectroscopy and microscopy. To provide experimental evidence for the hypothesis that interplanetary transfer of the genetic material is possible, phage T7 and isolated T7 DNA thin films have been exposed to selected space conditions: intense UVC radiation (lambda=254 nm) and high vacuum (10(-4) Pa). The effects of DNA hydration, conformation and packing on UV radiation damage were examined. Characteristic changes in the absorption spectrum, in the electrophoretic pattern of DNA and the decrease of the amount of PCR products have been detected indicating the photodamage of isolated and intraphage DNA.     

Spatial coherence and electromagnetic wave generation during electron beam experiments in space

A two-dimensional electromagnetic simulation model is used to investigate the production of whistler waves in connection with electron beam experiments in space. The spectrum is observed to peak near 0.7 ω_e, and the conversion efficiency of beam energy to whistler waves is about 5 × 10⁻⁵. The whistlers can be trapped in a density trough extending out from the spacecraft and experience ducted propagation.