Space environment measurements by JAXA satellites and ISS

In order to monitor space environment and its temporal variations, JAXA (Japan Aerospace Exploration Agency) Space Environment Group has been conducting space environment measurements for more than 20 years. We installed space radiation detectors, magnetometers and plasma detectors on LEO (Low Earth Orbit) satellites, GEO (Geostationary Orbit) satellites, GTO (Geostationary Transfer Orbit) satellites and JEM (Japanese Experimental Module) of the ISS (International Space Station). With these data, some distinguish achievements on space environment science and technology have been obtained and the assessment of space environment models has been made. Advanced radiation belt model, which accommodates temporal and spatial variations of relativistic electrons in the radiation belts, was proposed. Intensity of MeV electrons seems to be controlled by the solar wind velocity as well as the magnetic activity. With this relation, we have constructed advanced electron radiation belt model. Galactic cosmic ray and solar cosmic ray measurements by ISS/JEM is one of the big achievements. We are using these space environment data brought by JAXA satellites and ISS to see situation of space environment in real-time and we provide warning messages to the satellite operators as well as ISS/JEM manager when the space environment will be harmful. In this paper, we demonstrate current JAXA activities in space environment measurements together with new projects.