宇宙科学研究所
The Ionospheric Measurement Sensor (IMS) is composed of a Langmuir probe (LP) and of the Electron Temperature Probe (ETP) developed by K. Oyama (Institute of Space and Astronautical Science (ISAS), Japan). LP measures the in-situ electron temperature and density and ETP measures the in-situ electron temperature and floating potential. The instrument monitored the variation of the nighttime ionosphere along the satellite track until the unexpected power failure of the probes on 2 August 2001.