Institute of Space and Astronautical Science

In-flight receiver calibration of the Ganymede Laser Altimeter (GALA) by passive Earth observations

Abstract. Post-launch characterization of the receiver telescope of the laser altimeter is essential for achieving precise georeferenced planetary measurements and for radiometric calibration to passively measure surface reflectance. For the Ganymede Laser Altimeter (GALA) aboard...

A survey of the reconnection layer around Mercury’s magnetopause

An anomalous reconnection layer (ARL) forms in the Earth’s magnetosheath near the magnetopause when the solar wind has a low Alfvén Mach number. This ARL structure is similar to a magnetic reconnection outflow region and is characterized by a weaker total magnetic field and a hig...

Hour-scale response of low-Earth-orbit satellite altitude to extreme geomagnetic storms revealed by the NinjaSat CubeSat during the 2024 solar maximum

Abstract Extreme geomagnetic storms accelerate low-Earth-orbit satellite decay by inflating the thermosphere, yet the hour-scale pathway from solar-wind energy to atmospheric heating is poorly understood. Using the GNSS receiver of the NinjaSat CubeSat ( $$\sim 500$$ km, $$97^\ci...

Estimation of auroral emission altitude in the region of the ISS magnetic footprint during a relativistic electron precipitation event observed by ISS-CALET

We report a multi-MeV relativistic electron precipitation (REP) event as observed by the CALorimetric Electron Telescope and the Monitor of All-sky X-ray Image aboard the International Space Station, together with low-cost twin all-sky auroral imagers installed at Athabasca, Cana...

Flying through the plasmasphere to optimize low-energy ion measurements

The Juice flyby of Earth in August 2024 gave us the first chance to evaluate the performance of the Jovian Plasma Dynamics and Composition analyzer (JDC) in environments similar to those expected at Jupiter. JDC is one of the sensors belonging to the Particle Environment Package...

The parent bodies of Ryugu and Ivuna formed before those of other carbonaceous chondrites

Most carbonaceous chondrite (CC) meteorites contain abundant chondrules, millimeter-scale spherical inclusions of previously molten material. Ivuna-type carbonaceous chondrites (CIs) do not contain chondrules, nor do samples of the carbonaceous asteroid Ryugu. CIs and Ryugu share...

Effect of oxygen ion irradiation on the visible, infrared, and Raman spectra of Phobos candidate materials: implications on the space weathering by Martian atmosphere-derived ions

Abstract The origin of Martian satellites is still under debate. Nevertheless, such information could give insights into the evolution of the Martian system and planetary formation processes. To address these questions, MMX (Martian Moons eXploration) will conduct spectroscopy (v...

Comparative Analysis of Ion and Electron Contributions to Ionospheric Ionization at Auroral and Subauroral Latitudes

Abstract Electron and proton precipitation into the nightside ionosphere is a key process in magnetosphere–ionosphere coupling. Although auroral electron precipitation at –10 keV is traditionally considered the main driver of auroral emissions, recent studies show that keV electr...