Masatsugu Otsuki

This paper presents the current development status of the optional payload named Lunar Excursion Vehicle (LEV) for the Japanese future Lunar landing mission SLIM. The deployable exploration system LEV is released from the lander at the few meters above the Lunar surface after the lander's terminal deceleration is finished. LEV consists of two probes that will move and observe around the landing site autonomously. They also help acquire the evidence of SLIM landing by taking pictures of the final status of the lander.

The world's smallest moon lander (OMOTENASHI) will be launched by NASA's space launch system. The lander impacts to the moon at 100km/h. The landing impact is absorbed by crushable materials and an airbag consisted of an external cover and an air chamber made by polyimide films. However, the coexistence of tough glued strength and lightweight will not be expected. Meanwhile, welding technique for polyimide films has been proposed which can be fabricated stronger and lighter than the glued films. In this paper, the development of the air chamber fabricated by using the welding technique for polyimide films is shown.

DESTINY+ is a flyby space mission for the asteroid named Phaethon and will be launched in 2022. Camera system in Flyby space mission has been conventionally controlled by a PD controller. However, PD controller cannot generally consider constraints. A flyby mission requires a robust control for constraints in traversing at high-speed. This paper proposes a control scheme based on Model predictive Control for a flyby mission with robustness for constraints of input and angular velocity. The simulation study shows that Model predictive Control is effective for robustness in a flyby mission.

When the lander carries a large amount of fuel, the landing on a celestial body becomes difficult and dangerous due to sloshing of fuel. Sloshing of fuel causes turbulence of attitude and overturning of the lander. In order to design a landing gear and attitude control system, landing simulation with a sloshing will be required. The mechanical sloshing model that takes the place of experiment and computational fluid dynamics is required for the landing simulator. This paper describes the modelling of mechanical concentrated-constant sloshing models for a landing simulator and the result of numerical simulations of landing on a small body celestial bodies.

Understanding the interaction between granular materials on surface of a small body and a spacecraft is the key issue to design equipments of the spacecraft utilized in a future planetary exploration. Aiming to realize a safe long-term stay on the small body, this paper presents the experimental results that acquired the basic data about the interaction through the drop tower test.

<p>This paper describes the design of the hopping rover for the moon or Mars surface exploration. Hopping rover is one of solution for locomotion on loose and rocky terrain on the moon and planetary surface. The hopping rover can jump over an obstacles. Since the height of hopping is equal to the height which the rover can get over, the traversability of rover becomes higher than that of the small wheeled rover. In this paper, we describe the whole design of the hopping rover, design of hopping mechanism, simulator with the estimation of terrain force, action strategy, and the scientific missions.</p>

<p>Planetary surface mobility is one of the key technologies for future deep space missions. However conventional rovers are so big and expensive. To enhance robotic surface exploration missions, small, light-weight explorers are required. Therefore this paper proposes a new hopping locomotion system for small planetary rover using shape-memory-alloy(SMA) actuator. The proposed mechanism is analysed based on SMA constitutive mathematical model. Simulation results show that proposed mechanism has the capability of horizontally 2.5 m jump under the 1/6 gravity environment.</p>

This study discusses an airbag system as a landing gear of a spacecraft for a planetary exploration. The inflated airbag has the capability to attenuate impact acceleration at the instant of landing and submergence into regolith that covers a planetary surface. Crash tests in this paper verify the attenuation performance of the airbag and specify an issue.