Ion temperature and relative ion composition measurements from a low-altitude polar-orbiting satellite

An ion energy analyzer has been flown on a recent (November 9-11, 1965) low-altitude polar-orbiting satellite. The data were collected, partially analyzed while in flight by the instrument, and stored on tape to be read out at convenient satellite tracking stations. The data sampling rate was once every three seconds, which permitted a very detailed measure of the latitude variation of ion temperature, concentration, and relative ion composition. Large temperature fluctuations were observed in the nighttime northern high-latitude regions. Mid-latitude daytime ion temperatures generally varied between 400 and 1000°K. High temperatures were observed in both the daytime southern auroral zone and the nighttime northern auroral zone. The midlatitude trough in ion concentration was observed a L = 4.5, while other sharp troughs were located at about L = 1.5.