Examined solar radiation, thermospheric structure. SRATS (Solar and Thermospheric Radiation Satellite) is the third Japanese scientific satellite, to study the intereffects of solar radiation and the thermosphere of the earth. National name: Taiyo. Launch time 0525 GMT.

JETS-1 (Japanese Engineering Test Satellite -1, national name 'Kiku') is intended for preliminary experiments for confirmation of the launching technologies, acquiring the satellite tracking and control technologies, and for extension tests of the extenda ble antennas, measurement of satellite environment, measurement of satellite attitudes, etc. Launch time 0530 GMT.

Ionospheric sounding. Japanese Ionospheric Sounding Satellite (JISS - national name 'Ume') is intended for regular observations by means of radio waves of the global distribution of the critical frequencies of the ionosphere, and for utilization of the results of the observati on for radio wave forecasts and warning necessary for effective operation of short-wave radio-communication. Time of launch 0330UT.