Masashi Abe
(JAXA, Japan)

Our team started Space based Automatic Identification System Experiment(SPAISE) in April, 2010. The Automatic Identification System(AIS) is a ship-to-ship and ship-to-shore system used an aid for collision avoidance and vessel traffic management. AIS signals consist of short messages, broadcast at VHF, that contain information such as ship ID, position, speed and heading, etc. In recent years, JAXA promotes utilization of remotes sensing techniques by satellites in the field of ocean. Especially, our team have considered next generation satellite network system for maritime security and safety. SPAISE is the first step of this system. This experiment has two missions which are engineering tests, and verification of the usefulness of the signals for maritime security and safety. On engineering tests mission, we develop the AIS receiver for mounting satellites, and signal analysis algorithm. On the other mission, we will investigate validity of space born AIS signals with joint researchers who use AIS data for them jobs. The satellite which use for SPAISE is JAXA's small demonstration satellite 4(SDS-4). SDS-4 will be launched at November, 2011. After the experiment, we will develop a next-generation AIS receiver based on the findings from this study for second step of our plan.

Morio Toyoshima
(NICT, Japan)

Space communications by lightwave have various advantages such as smaller and lighter equipment, higher data rate, larger communication capacity, and limited risk of interference with other optical communication systems. Many organizations in the world have been researching and developing the optical space communications technologies for space infrastructures to support various space activities. At the National Institute of Information and Communications Technology (NICT) in Koganei, Japan, a laser communication demonstration between the NICT optical ground station and a low earth orbit satellite was successfully conducted in 2006 to 2009. The polarization characteristics of an artificial laser source in space were measured through space-to-ground atmospheric transmission paths. Stokes parameters and the degree of polarization of the laser beam transmitted from the satellite were measured. These results contribute to the link estimation for quantum key distribution (QKD) via space and provide the potential for enhancements in QKD worldwide in the future. After this experiment, NICT has begun to develop a Small Optical TrAnsponder (SOTA) onboard a small satellite, which project is called the Space Optical Communications Research Advanced TEchnology Satellite (SOCRATES). In this mission, basic QKD experiments are planned. In this paper, the verification plan of basic QKD experiments is presented.

Yuta Fujii
(Mitsubishi Electric Corporation, Japan)

In the future, earth orbiters including observation satellites and geostationary satellites would be required to transmit a large amount of data at a fast rate. The use of laser beams to communicate between two satellites is thought to be one of the effective methods to realize such transmission. The difficult point is to track the other satellite with a few microradians using the high directivity of the laser beams. The accurate detection of the center position of the spot image created on an image sensor by focusing the received laser beam makes it possible to track the satellite. In this paper, an algorithm for the accurate detection at a sub-pixel resolution is presented. By combining the conventional algorithm with the proposed centroid algorithm using a weight map with a modified circular shape, the accuracy of detection can be increased more. This is confirmed by performing numerical simulations using virtual spot images that are created on the basis of optical wavefront calculations. The effectiveness of the proposed algorithm is also confirmed when the image contains some noise, when the spot image exhibits shape variations because of changes in the f-number, or when the image is defocused.

Tomoyuki Ikeda
(Osaka Institute of Technology, Japan)

In the Project of Osaka Institute of Technology Electric-Rocket-Engine onboard Small Space Ship (PROITERES), a nano-satellite with electrothermal pulsed plasma thrusters (PPTs) will be launched in 2011. The main mission is to achieve powered flight of nano-satellite by an electric thruster and to observe Kansai district in Japan with a high-resolution camera. We developed Bread Board Model (BBM) and Engineering Model (EM) of the satellite, including electrothermal PPT system, high-resolution camera system, onboard computer system, communication system and grand station, electric power system, attitude control system etc, in 2007-2009. The development of the satellite Flight-Model (FM) was completely finished in 2010. In this paper, we introduce the final feature of development for the PROITERES satellite and the next projects of PROITERES satellites 2 and 3.