High precision composite pipes for SOLAR-B optical structures

The authors have been developing new high thermal conductivity and low moisture absorption composite pipes for high precision space optics applications on the Japanese Institute of Space and Astronautical Science (ISAS) SOLAR-B satellite.Pitch based K13C (Mitsubishi Chemical) high modulus and high conductivity graphite fiber, and EX1515 (Bryte Technology) low moisture absorption cyanate resin, were applied to the pipes.Thermal expansion of the composite pipes was designed to be zero and more uniform in the longitudinal direction in order to obtain long term dimensional stability in the space environment.Model pipes whose length was 500 mm were fabricated and evaluated for thermal and hygroscopic deformation in a new testing apparatus. Equivalent coefficient of thermal expansion of the model pipes was essentially zero (less than 0.1 ppm/°C) and standard deviation of these coefficients was 0.05 ppm/°C. Hygroscopic deformation of the model pipes was under representative conditions 7 ppm over 3 month. The excellent thermal and hygroscopic stability were verified. In addition, thermal conductivity of the model pipes was more than 200 W/(m · K).     

Bone metabolism and formation of mice bred in a 2 G environment.

The purpose of this study is to reveal the effect of chronic hypergravity exposure on the bone formation and the bone metabolism when mammals produce offspring in a 2 G environment. We measured the length and width of the thighbone, the length of the pelvis, the width of the pelvic cavity and the width of the fourth cervical vertebra on the second (F2) and the third (F3) generation mice bred in a 2 G environment every ten days from 20 days old to 60 days old in an experiment on bone formation. In an experiment on bone metabolism, we measured calcium and phosphorus in the bones of the F3 in the 2 G group. Ratios of the thighbone length, pelvis length, pelvic cavity width, and fourth cervical vertebra width versus the body length were calculated. These ratios were higher in the 2 G group than the control group during all measuring periods. Calcium and phosphorus concentrations in the thighbone and the lumbar vertebra were lower in the 2 G group than in the control group. However, the calcium and phosphorus concentrations in the cervical vertebrae of the 2G group were higher. These results suggest that the influence of gravity load may vary in the bones.     

Differential positioning experiment using two geostationarysatellites

A ranging and positioning system for a ship or an aircraft using two geostationary satellites is described. This system has a ranging and positioning accuracy of 100 m and 1 km. Experiments to estimate this system were performed using a ship in the Pacific Ocean in a normal and a differential modes. This system leads to the development of fundamental ranging and positioning techniques for the cooperated independent surveillance