Recently, the technology of small/nano satellites has developed remarkably and is expected to apply to planetary exploration. The planetary orbit insertion technology is indispensable for fruitful planetary explorations in the future. However, the orbit insertion maneuver using a chemical propulsion is not realistic for the small/nano class spacecrafts because of its severe resource constraint. An aerocapture technology is attractive. This research focuses on the drag-modulation aerocapture in Mars using a large-area and low-mass inflatable aeroshell. In this concept, the atmospheric entry vehicle with an inflatable aeroshell jettisons its aeroshell at the appropriate time during the atmospheric entry in order to acquire the necessary atmospheric deceleration to insert the Mars orbit. The feasibility of Martian aerocapture for the small/nano class spacecrafts is proved by the orbital trajectory simulation with the atmospheric entry. Especially, focusing on the algorithm to determine the time of the aeroshell jettison, the relation between some algorithms and the accuracy of the orbit insertion is evaluated using Monte Carlo simulation. It demonstrated that the algorithm depending on a combination with time and total deceleration velocity can increase the accuracy of the orbit insertion.

Low-level wind shear poses a risk of hard landings and accidents for aircraft in the landing phase. Predicting such low-level wind shear is challenging without clearly understanding its mechanisms. To clarify the mechanism of low-level wind shear generation at Shizuoka Airport, where wind shear warnings are frequently activated, we comprehensively compared and verified data from aircraft onboard record data (Quick Access Recorder), Doppler lidar observations, and numerical simulation analysis. The results revealed that strong westerly winds at the airport are induced by downdrafts caused by the descent of the upper stable layer due to the influence of the terrain along the wind path. These strong winds are disturbed by the hill located at the southeastern end of the airport, creating a weak wind zone along the landing path. This downdraft and weak wind zone suggest an environment conducive to activating wind shear warnings. Since wind shear is attributed to meteorological and topographical factors, pressure patterns and wind directions/speeds that easily lead to strong winds can be utilized for wind shear prediction. Additionally, knowing the location of the weak wind zone may help identify areas where the pilot should pay attention during maneuvers, potentially reducing the pilot's workload.

This research aims to clarify the effects of folding on the mechanical and electrical characteristics of a transmission line consisting of two membrane layers. To realize a lightweight and compact membrane antenna, it is essential to clarify the transmission characteristics of a transmission line when it is folded. In this research, we investigated (1) the geometry of a transmission line with a folding habit, (2) the series impedance and parallel admittance of a transmission line when it is deformed, and (3) the relationship between the folding habit and the reflection coefficient. First, for (1), the tension and initial deflection angle effects on the membrane were significant, while the impact of spring stiffness on the membrane shape was small. Next, for (2), it becomes clear that the same theory of inhomogeneous transmission lines can be used for lines with varying widths, such as tapered transmission lines, and lines with different thicknesses in a distributed manner, such as two membrane layer transmission lines. Finally, for (3), it becomes clear that the reflection coefficient approaches zero when the tension is strong, the folding habit is weak, and the reflection coefficient increases when the tension is weak or the folding habit is strong.

Conventionally, the double-probe method is used to observe the electric field by the sounding rockets. In the double-probe method, two pairs of dipole antennas are equipped to observe the electric field of two orthogonal components in the spin plane perpendicular to the rocket axis. In this study, we establish an electric field analysis method using one pair of dipole antennas and investigate its error in order to reduce the size of the detector and the risk by reducing the number of extensions. The results show that the magnitude of the electric field has an error of ±12% and the direction of the electric field vector has an error of ±4^º.