Hypogravity (low G) has been known to elicit many changes in automatic and endocrine functions which may be regulated by the hypothalamus. We investigated hypothalamic neuron activity during low-G simulation and its involvement on regulation of muscle electrolytes and Ca metabolism. 1) In unanesthetized rats, about 50% of neurons of the lateral hypothalamic area (LHA) showed changes in activity during horizontal suspension. About 40% of neurons of the paraventricular necleus (PVN) showed changes in activity during head-down tilt suspension. Inputs from barorecestors and/or vestibular system seem to affect both LHA and PVN neuron activities, while proprioceptive information mainly affect LHA activity. 2) Electrophysiological experiments revealed that polysynaptic excitation from the vestibular nucleus and monosynaptic inhibition from the fastigial nucleus were main inputs to the LHA. 3) Rats under conditions of long-term hypokinesia, potassium-deficient diet or DOCA (deoxy corticosteron acetate) -salt hypertension show increase and decrease in intracellular concentration of sodium and potassium ions, respectively, in muscles. Lesion of the ventromedial hypothalamus (VMH) or PVNreduced the electrolyte changes in the muscle. VMH activity through sympathetic nerve are involved in regulation of Na-K pump activity in the slow muscles, while endogenous Na-K ATPase inhibitor in the PVN and the anteroventral region of the III ventricle is involved in regulation of Na-K pump activity in the fast muscles. 4) LHA neurons have calcitonine sensitivity and central injection of calcitonin reduced plasma concentration of Ca. These findings suggest that the hypothalamus is involved in regulation of calcium as well as other electrolytes.

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Recent and scheduled chemical analysis in space missions are reviewed. Recent progress in analytical chemistry have made it possible to analyze chemical cpmposition of extraterrestrial samples in space. VEGA-1 and Giotto utilized mass spectrometers to analyze cometary dust particles. Phobos I and II are flying toward Mars and its moons. They carry various instruments to analyze Martian atmosphere and surface material of Phobos. NASA is planning to launch unmanned spacecrafts with mass spectrometers on board to comets and Jupiter. Various kinds of organic compounds were/are being detected in extraterrestrial matters. These facts promote the study of chemical evolution toward origins of life in space.

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As a mission after MAGELLAN, which is the NASA's next Venus explorer and will be launched in April 1989 for making a Radar map, a Venus exploration program is proposed here with the special interest in the origin and evolution of Venusian atmosphere. This program will make the exact measurements of the compositions of clouds and atmosphere under the cloud, the composition and temperature of the surface, and topography. By these measurements, we aim at: manifesting whether an ocean was present in the past, whether lots of water have escaped from Venus, whether the volcanic activity is/was present now/in the past, whether the plate tectonics is/was present, etc. We will also Study in detail the dynamics in the lower atmosphere, the origin of sulfur compounds, the history in the topographic structures, etc. In consequence, this program will use an orbiter and a balloon which will make a ground-base observation after the landing on the surface. More detailed description in English is available in the paper: A.Matsuzaki, ''Venus Exploration Relevant to Origin and Evolution of its Atmosphere Origin of Sulfur Dioxide as a Clue'', Proceedings of the 21 st ISAS Lunar and Planetary Symposium, July 7-9 1988, in press.

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The author shows his own view on exobiology, which are inspired by the discussion with his colleague NASA researchers. The profiles of these active NASA-Ames researchers are sketched. No ongoing NASA researchers are described here.

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