Jun'ichiro Kawaguchi

Since 2008, a new plan for next Mars exploration program has been proposed and discussed by scientists and engineers in Japan. This exploration program is named MELOS, or Mars Exploration with Lander and Orbiter Synergy, a long-awaited program in the planetary science community in Japan after unsuccessful end of Nozomi Mars orbiter and ongoing challenge of Akatsuki Venus orbiter. The goal of the whole program is to understand Mars as a system, by elucidation of Martian climate, atmospheric escape, internal structure, surface environment and interaction by them. A series of missions has been planned, and several spacecraft including orbiters and landers are under discussion to be launched in early 2020's. In this paper, we investigate launch opportunities during early 2020's and estimate the payload mass in each case. Feasible interplanetary transfer trajectories from Earth to Mars are proposed. Preliminary design of insertion sequence into the Mars orbit and some orbit candidates derived from mission requirements are also shown together with numerical simulation results.

Japan Aerospace Exploration Agency (JAXA) successfully achieved the world's first solar power sail technology by IKAROS (Interplanetary Kite-craft Accelerated by Radiation Of the Sun) mission in 2010. It demonstrated a photon propulsion and thin film solar power generation during its interplanetary cruise. The 200m2-span sail was deployed and kept extended by centrifugal force of the spacecraft rotation. IKAROS also succeeded in accelerating and controlling the orbit by actively exploiting solar radiation pressure, and thus became the world's first actual solar sailer flying an interplanetary voyage. This paper presents the design of IKAROS solar sail system, operation results and introduces a perspective of this new technology to apply to the next generation mission toward Jupiter and Trojan asteroids.

General description, communication subsystem configuration and rescue operation after communication link down about the Asteroid Explorer "Hayabusa" which was launched on May of 2003, arrived at Asteroid "Itokawa" on September of 2005 and finally returned to the earth on June of 2010, are described.

The Japan Aerospace Exploration Agency (JAXA) makes the world's first solar power sail craft IKAROS demonstration of photon propulsion and thin film solar power generation during its interplanetary cruise. The spacecraft deploys and spans a membrane of 20 meters in diameter using the spin centrifugal force. It also deploys thin film solar cells on the membrane, in order to evaluate its thermal control property and anti-radiation performance in the real operational field. The spacecraft weighs approximately 310kg, launched together with the agency's Venus Climate Orbiter, AKATSUKI on May 21, 2010. This paper presents the summary of development and operation of IKAROS.

The asteroid explorer Hayabusa, which is the spacecraft for asteroid sample return mission of Japan, came back to the Earth on June 13, 2010, seven year after the launch. It is the first spacecraft in the world that went to a solar system body farther than the moon, touched down on its surface, took off, and came back to the earth. Hayabusa has many new challenges; some of them were successful but others were unsuccessful. As the results, Hayabusa revealed the strange nature of a small near earth asteroid, Itokawa. In this paper, we describe the whole mission of Hayabusa.

The Japan Aerospace Exploration Agency (JAXA) will make the solar power sail craft demonstrate for both its photon propulsion and thin film solar power generation during its interplanetary cruise. The spacecraft deploys and spans its membrane taking the advantage of the spin centrifugal force. The deployment system of large membrane was developed. The overall deployment experiment of solar power sail using a balloon was planned. However the balloon was not launched due to the bad weather. In this paper, the contents and significance of the experiment are reported.