Telescope of extreme ultraviolet boarded on KAGUYA: Science from the moon

We have succeeded in observations by the Telescope of Extreme Ultraviolet (TEX) aboard Japan's lunar orbiter KAGUYA to characterize the evolution of the Earth's plasmasphere. The view afforded by the KAGUYA orbit encompasses the plasma distribution in a single exposure, enabling us to examine for the first time the globally-averaged properties of the plasmasphere from the side (meridian) view. We focus on a study period that began with a likely moderate erosion event of plasma patches in a geomagnetically disturbed period, and follow refilling of plasma from the upper ionosphere. The Earth's plasmasphere grew up to saturated level at the rate of approximately 1,600 km per day to 4,800 km per day on the equatorial plane. From the “side view” of the Earth, a specific magnetic flux tube with cold dense plasmas was seen and likely moved to outer magnetosphere, even while geomagnetic activity was low. From the moon, we are studying the terrestrial plasmas in the vicinity of the Earth. This is called “Geoscience from the Moon”.