Harunori Nagata

Proposal of procedure of thermal design on micro and nano satellites pointing to Earth

A procedure for the thermal design of micro and nano satellites is proposed in order to complete the thermal design of micro and nano satellites for about 1 year. Two concepts of thermal design are considered to keep the temperature change of components within the design temperature range of components. One concept is to decrease the temperature change using the whole heat storage of the micro and nano satellite. The other is to decrease the temperature change of the inner structure where the components with the narrow design temperature range are mounted. The temperature of micro and nano satellites designed in the former concept is calculated using one nodal analysis method. The temperature of micro and nano satellites designed in the latter concept is calculated using two nodal analysis method. The combinations of optical properties on structures and components to keep the temperature within the design temperature range of components are clarified using one or two nodal analysis. Then, the multi-nodal analyses are carried out to be designed in detail based on the optical properties clarified from the one-nodal analysis and two nodal analysis. This procedure of thermal design is applied to Hodoyoshi-1 satellite. Hodoyoshi-1 satellite is the micro satellite that is about 50 cm in width, 50 cm in depth, 50 cm in height, is about 50 kg in mass, has two inner plates, has solar cells on the body, flies on the sun-synchronous orbit of the 500 km of altitude and is pointing to the Earth. The thermal design of Hodoyoshi-1 satellite has been completed for about ten months. The validity of this procedure is confirmed and the problems of this procedure are clarified.

Ignition Delay of Premixed Gases under Microgravity Conditions

There have been many studies of hot surface ignition of premixed combustible gases reported in the literature. In these studies, all experiments were made under normal gravity condition, suffering from the complicated effect of gravity. Therefore, it is very difficult to interpret these results and also to investigate the ignition mechanisms.