An imaging telescope for high energy gamma-ray astronomy

Recent tests of a γ-ray imaging telescope, which incorporated a coded aperture mask and multi-wire proportional counter system produced good images of a tritium target source which was used to generate the 20 MeV protons at a proton Van de Graaff accelerator. This paper indicates what performance one might expect if a large area drift chamber were used in conjunction with a coded aperture mask. The prospects for achieving significant scientific results if such a system were flown on a variety of space vehicles are discussed.     

A prospectus on airborne laser mapping systems

Airborne laser systems have demonstrated enormous potential for topographic and bathymetric mapping. Both profiling and scanning systems have been evaluated for terrain elevation mapping, stream valley cross-section determination, and nearshore bottom profiling. Performance of the laser systems has been impressive and for some applications matches current operational accuracy requirements. Determining the position of individual laser measurements remains a constraint for most applications. Laser technology constrains some terrain and bathymetric applications, particularly for water penetration and frequency of measurements for high-spatial resolution over large areas.     

Prospecting in glaciated terrain-integrating airborne and Landsat MSS

The effects of a glacially enriched zone of trace elements on soils and vegetation in the Thetford Mines area of Quebec were investigated using ground information plus digital Multispectral Scanner (MSS) data from airborne and Landsat sensors. The enriched zone was developed during the last glaciation when a southeastward flowing glacier eroded and dispersed an ultrabasic outcrop that had anomalous levels of Ni, Cu, Co, Cr, Mg and Fe.The dispersal train of enriched trace elements was detectable over an area at least 70 × 15 km ‘down-ice’ from the outcrop. In this zone total Ni concentrations in the soil ranged from background levels of 10 ppm to levels in excess of 1800 ppm. The dominant tree species, $\text{Abies}$$\text{balsamea}$ (balsam fir) and $\text{Picea glauca}$ (white spruce) reflect the soil anomaly with higher concentrations of trace elements in their tissue and lower concentrations of chlorophyll.An unsupervised enhancement of Landsat imagery showed that a tonal discontinuity was caused by a vegetation segregation related to the heavy metal enrichment soils. A detailed study based on Landsat MSS data was able to establish regional patterns of chlorophyll production by certain plant species closely related to the ultrabasic dispersal train. Multi-channel airborne MSS data confirmed the Landsat soil-plant patterns.     

Conception of spacecraft centralized power supply

A reliable power supply for spacecraft is one of the central problems determining the future development of space technology. The traditional solution to this problem implies having an autonomous power plant on board each spacecraft. The most widely used are power plants with solar cells. However, there exists an alternative power supply concept of using a centralized power supply system (CPSS) and power transmission to the user satellites by laser or microwave beams. Use of a CPSS has a number of advantages. In particular, it allows the spacecraft to increase power supply level and service life as well as to decrease the spacecraft mass and cost. However, it sets new physical and technical problems associated with long distance power transmission and requires some changes in spacecraft structure and concepts. The feasibility study of CPSS development and use has to rely on existing or firmly forecastable technologies. An attempt of such an analysis has been done by a group of scientists at Moscow State Aviation Institute during 1994-1996. The very first results have already been published. This paper discusses new results obtained lately regarding a space based CPSS     

Population inversion and gain distribution in supersonic mixed flow systems

Experimental results are reported for small signal gain distribution across a cavity of a mixed flow gasdynamic laser system at different turbulent supersonic mixing regimes. It is shown that the temperature range of the GDL generation regime can be extended up to 7000°K, and gain coefficients as high as 3.5 m⁻¹ be attained in a “double-freeze” supersonic gas flow. Basic advantages are discussed as well as the opportunity to obtain higher efficiencies in thermally pumped laser systems.     

Simulation of space cabin atmosphere

The Soyuz 22 space cabin atmosphere was studied for volatile organic trace contaminants. By gas chromatography the following constituents were identified: methane, ethane, heptane, methanol, ethanol, n-propanol, acetaldehyde, acetone, ethyl benzene. Except for acetone, concentrations of the above compounds were close to the values determined in the mock-up experiments.     

Ionospheric electron heating by a rocket borne electron accelerator

A “mother-daughter” rocket code-named “Electron 2” was launched from And?ya, Northern Norway in November, 1978. The “daughter”, carrying a 10 keV electron accelerator, was separated from the “mother” payload with a speed of 0.4 m/s. A series of plasma diagnostic instruments were included on the “mother” to study effects produced by the interaction between the electron beam and the ionospheric plasma. Results obtained by two different plasma probes are presented. It was found that pronounced changes in the ambient electron population took place in regions penetrated by the electron beam. Estimates of the dimensions of the disturbed region are presented.     

Thermal and nonthermal flare emission observed with the Nobeyama Radio Heliograph

The early phases of three flares, observed by the Nobeyama Radio Heliograph, are studied. Nonthermal and thermal radio sources are identified by comparison with soft X-ray images taken by the Soft X-ray Telescope onboard the Yohkoh satellite. Two of the flares are mainly of nonthermal origin and their location coincides with one of the footpoints of soft X-ray loops. Another flare has both thermal and nonthermal components which start to brighten simultaneously. This suggests that particle acceleration and plasma compression develop simultaneously.     

The properties of alamethicin incorporated into planar lipid bilayers under the influence of microgravity.

During evolution, life on earth had adapted to the gravity of 1g. Due to space flight, in the last decades the question arose what happens to the brain under microgravity on the molecular level. Ion channels among others are the molecular basis of brain function. Therefore, the investigation of ion channel function under microgravity seems to be a promising approach to gather knowledge on brain function during space flight. In a first step, the ion channel forming peptide Alamethicin was used as a model channel in an artificial membrane. It is well suitable for this kind of investigation, since its properties are well described under standard gravity. For that reason, changes due to microgravity can be detected easily. All experiments were performed in the German drop tower at ZARM-FAB, Bremen. A special set-up was constructed based on the bilayer technique introduced by Mueller and Rudin. All functions of this set-up can be observed and controlled remotely. In the first set of experiments, a dramatic change of electrical properties of Alamethicin under microgravity could be observed. Mainly, the pore frequency is significantly reduced.     

Assessing the plausibility of life on other worlds

As the field of astrobiology matures and search strategies for life on other worlds are developed, the need to analyze in a systematic way the plausibility for life on other planetary systems becomes increasingly apparent. We propose the adoption of a simple plausibility of life (POL) rating system based on specific criteria. Category I applies to any body shown to have conditions essentially equivalent to those on Earth. Category II applies to bodies for which there is evidence of liquid water and sources of energy and where organic compounds have been detected or can reasonably be inferred (Mars, Europa). Category III applies to worlds where conditions are physically extreme but possibly capable of supporting exotic forms of life unknown on Earth (Titan, Triton). Category IV applies to bodies that could have seen the origin of life prior to the development of conditions so harsh as to make its perseverance at present unlikely but conceivable in isolated habitats (Venus, Io). Category V would be reserved for sites where conditions are so unfavorable for life by any reasonable definition that its origin or persistence there cannot be rated a realistic probability (the Sun, gas giant planets). The proposed system is intended to be generic. It assumes that life is based on polymeric chemistry occurring in a liquid medium with uptake and degradation of energy from the environment. Without any additional specific assumptions about the nature of life, the POL system is universally applicable.