Ryuichi Mitsuhashi

Attitude estimation of nano-satellite “HIT-SAT” using received power fluctuation by radiation pattern

In this paper, it is verified that the angular velocity of the small satellite can be estimated from the cycle of the received signal intensity. Estimated angular velocity from received signal coincides with that valuated from on-board sensor of gyro and magnetometer. It will be possible that high sampling rate and multi position measurement as demonstrated in this experiment gives us more information about satellite attitude.

Motion Analysis of Captive Platform System Constructed from Airship and Tether

The existence of a platform at the stratosphere is expected to be the role to gain a foothold in space. When the platform is employed airship in, it is transported by advection due to its lighter-than-air body. Thereupon, a mooring of platform is reasonable in order to incarnate fixed-point platform. Conception of a captive platform system is similar to the Rockoon one which rendered remarkable services for the space observation of the early days. Therefore, the application of captive platform system to the launch site is highly expected in order to realize the space transportation system with a large quantity and high frequency. In this study, the motion of a captive platform system constructed from an airship and tethers is analyzed in order to ensure that the motion of a captive platform system is practically incarnated. Moreover, the sensitivities of aerodynamic performance and buoyancy of the airship is observed. Consequently, the practically incarnated motion of a captive platform system has been identified under the condition of the storm environment. Furthermore, the reduction of the advection distance driven away by the storm has been quantitatively indicated under the different conditions of aerodynamic performance and buoyancy of the airship. The sensitivities of the lift and buoyancy of the airship for the motion of a system has been revealed in order to conceptually design airship geometry.

Feasibility Studies on a High-Altitude Captive Lighter-Than-Air Platform System

A station-keeping platform in the stratosphere can be a novel foothold toward spaceactivities. If the platform is conformed as free-ight LTA vehicles, there are possibilitiesthat they may be blown away by the atmospheric advection due to its free-ight nature.Therefore, mooring this type of platform to the ground by a cable will be much easierto hold it in position. This concept of a captive platform system looks somewhat similarto rockoon systems which provided remarkably good services for the space observation inthe past days. Namely, application of a captive platform system to a rocket launch padis well expected to realize a space transportation system of ample payload capacity withmuch frequent services. In addition, this newly conceived system will have a wide spectrumrange of application elds such as agriculture, meteorology, communication, etc. However,several technical issues are identi ed to materialize such a captive stratospheric platform.In these studies, summary results are presented for each of these technical issue itemsregarding ight tests, tether system operation, and wireless communication experiment.Consequently, useful knowledge has been empirically acquired concerning the above issuesin order to construct a captive LTA stratospheric platform.