Development of a plant growth unit for growing plants over a long-term life cycle under microgravity conditions.

To study the effect of the space environment on plant growth including the reproductive growth and genetic aberration for a long-term plant life cycle, we have initiated development of a new type of facility for growing plants under microgravity conditions. The facility is constructed with subsystems for controlling environmental elements. In this paper, the concept of the facility design is outlined. Subsystems controlling air temperature, humidity, CO2 concentration, light and air circulation around plants and delivering recycled water and nutrients to roots are the major concerns. Plant experiments for developing the facility and future plant experiments with the completed facility are also overviewed. We intend to install this facility in the Japan Experiment Facility (JEM) boarded on the International Space Station.     

The Galaxy Cluster Mass Scale and Its Impact on Cosmological Constraints from the Cluster Population

Space Science Reviews - The QB50 mission is a satellite constellation designed to carry out measurements at between 200–380 km altitude in the ionosphere. The multi-needle Langmuir probe...     

The quiescent spectrum of 2S1636-536

During the EXOSAT observation of 2S1636-536 in July 1983 the quiescent flux was observed to brighten from 1.7×10 ^-9 ergs/cm. ² /sec to 2.6×10^-9 ergs/cm. ² /sec, this increase being accompanied by a decrease in effective temperature. Further analysis of the spectrum reveals that the best fit is a power law with an index which increases from -1.75 to-2.1 while the source brightens; there is some evidence for an upper cut off. This spectrum is interpreted as the result of soft photons from the neutron star surface which are Comptonised in a hot plasma cloud surrounding the neutron star (neutron star corona). The increasing spectral index is seen as the result of Compton cooling of the corona as the output of quiescent flux rises in response to an increasing accretion rate.     

The Venus ionosphere

Physical properties of the Venus ionosphere obtained by experiments on the US Pioneer Venus and the Soviet Venera missions are presented in the form of models suitable for inclusion in the Venus International Reference Atmosphere. The models comprise electron density (from 120 km), electron and ion temperatures, and relative ion abundance in the altitude range from 150 km to 1000 km for solar zenith angles from 0° to 180°. In addition, information on ion transport velocities, ionopause altitudes, and magnetic field characteristics of the Venus ionosphere, are presented in tabular or graphical form. Also discussed is the solar control of the physical properties of the Venus ionosphere.     

Kalman filter mechanization for INS airstart

A strapdown mechanization and associated Kalman filter are developed to provide both ground align and airstart capabilities for inertial navigation systems (INSs) using Doppler velocity and position fixes, while not requiring an initial heading estimate. Position update during coarse mode is possible by defining sine and cosine of wander angle as filter states and modeling the position error in geographic frame while integrating velocity in the wander frame. INS Global Positioning System (GPS) differential position due to GPS antenna moment arm can aid heading convergence during hover turns in helicopter applications. Azimuth error state in the fine mode of the filter is defined as wander angle error to provide continuous estimation of navigational states, as well as inertial/aiding sensor errors, across the coarse-to-fine mode transition. Though motivated by a tactical helicopter application, the design can be applied to other vehicles. Advantages over conventional systems in addition to the airstart capability include robustness and versatility in handling many different operational conditions     

Radiation chemistry of the hippocampal brain slice.

The in vitro hippocampal brain slice is a 0.4 mm thick neural network that can be used to study brain responses to radiation and related injuries. This preparation is unique in that it responds to ionizing radiation within minutes after exposure without complications from changes in vascularity, blood flow, blood pressure, etc. Electrophysiological studies have shown that x- and gamma-rays alter synaptic transmission and spike generation, elements of normal brain activity. To evaluate the role of hydroxyl free radicals (OH) in these changes, slices were exposed to dilute H2O2 solutions. EPR spin trapping experiments verified that OH is produced. Neural responses, while similar, were not identical to those due to radiation, possibly because of a different distribution of OH. Although H2O2 is freely diffusible, it produces OH at specific sites where, e.g. iron reduces it. In contrast, x- and gamma-rays produce OH more uniformly throughout the tissue. H2O2 may provide a better model for high-LET radiation where yields of radical products of water radiolysis are decreased and peroxide reactions predominate.     

Communicating across the solar system

The technological advances of the Space Age have enabled us to project our senses through complex instruments to the edge of the Solar System and beyond. The link back to Earth by the communication channel has provided us with a wealth of information. The vast improvement in communication capability, by a factor of 10¹⁸, from the launching of the first earth satellites to the capacity of the Voyager telecommunications link across the Solar System, is symbolic of both our technical prowess and our cultural development. The combination of data rate and extreme distance at the Voyager 2 encounters with Uranus and Neptune in 1986 and 1989 will require the ground network to perform an engineering feat of unequalled magnitude. This paper describes the engineering challenge of communicating with spacecraft at the limits of the Solar System and the engineering responses to that challenge.     

Photometric calibration and first results obtained with the UFT experiment on board the astron satellite

The UV telescope of 30 cm diameter equipped with a three channel scanner spectrometer aboard the highly eccentric orbit space station “ASTRON” is describedAbsolute calibration of the whole device is performed using spectra of standard stars, of which absolute values were obtained by TDI or IUE experiments. Several photometric controls have been made on the stability of the equipment after one year of operation which demonstrate reliability of some first results obtained by the UFT.The sensitivity curve of the spectrophotometric system has been observed with a reproducibility of 2σ = 10% or better.The repeated observation of one star (139 Tau) indicates that the overall performance exhibits the same quality after one year in orbit. The low resolution mode ($\text{Δ λ = 28}\text{A}\text{?}$) leads to a powerful new investigation of faint extended sources.     

Measurements of trace contaminants in closed-type plant cultivation chambers.

Trace contaminants generated in closed facilities can cause abnormal plant growth. We present measurement data of trace contaminants released from soils, plants, and construction materials. We mainly used two closed chambers, a Closed-type Plant and Mushroom Cultivation Chamber (PMCC) and Closed-type Plant Cultivation Equipment (CPCE). Although trace gas budgets from soils obtained in this experiment are only one example, the results indicate that the budgets of trace gases, as well as CO2 and O2, change greatly with the degree of soil maturation and are dependent on the kind of substances in the soil. Both in the PMCC and in the CPCE, trace gases such as dioctyl phthalate (DOP), dibutyl phthalate (DBP), toluene and xylene were detected. These gases seemed to be released from various materials used in the construction of these chambers. The degree of increase in these trace gas levels was dependent on the relationship between chamber capacity and plant quantity. Results of trace gas measurement in the PMCC, in which lettuce and shiitake mushroom were cultivated, showed that ethylene was released both from lettuce and from the mushroom culture bed. The release rates were about 90 ng bed-1 h-1 for the shiitake mushroom culture bed (volume is 1700 cm3) and 4.1 approximately 17.3 ng dm-2 h-1 (leaf area basis) for lettuce. Higher ethylene release rates per plant and per unit leaf area were observed in mature plants than in young plants.