The Middle Atmosphere Observation Satellite “OHZORA” aims to elucidate the structure and composition of middle atmosphere, and observation of magnetosphere and participate in the International Middle Atmosphere Program.

Name (pre-launch in parentheses) OHZORA (EXOS-C)
International Designation code 1984-015A
Objectives 1.Elucidation of structure and composition of middle atmosphere, and observation of magnetosphere
2.Participation in the International Middle Atmosphere Program conducted from 1982 through 1985
Launch Date 17:00, February 14, 1984 (JST)
Launch Location Kagoshima Space Center (Uchinoura)
Launch Vehicle M-3S-4
Weight 207kg
Shape 88cm high, 109cm long from face to face
Octagonal cylinder with four solar-array paddles
Extending 20m-long antenna from the body
Orbital Altitude Perigee 354 km, Apogee 865 km
Orbital Inclination 75°
Type of orbit Elliptical
Orbital Period 97 min
Scientific Instruments Limb Atmospheric Infrared Spectrometer
Planet Plasma Sounder
End of Operation December 26, 1988
Reentered Date December 26, 1988
Operation Since the satellite touched the 3rd-stage rocket motor five seconds after separation, it was contaminated by residual gas. Consequently, the satellite’s battery capacity fell by 20%. To cope with this drop, careful switch on/off operation of the observation instruments was made to prevent excessive battery discharge. After orbiting 26,799 times around the earth, the last signal from OHZORA was received at 14:11:53 on December 26, 1988 (JST), and then the communication link was lost. It is thought that the satellite perished at an altitude of 90km over New Guinea at 23:39 on that day.
Results Of 11 observation instruments, five were used for research of atmospheric environment and six for research on the earth's electromagnetic environment. During its four years of operation, OHZORA provided us with valuable data obtained by observations of absorption spectrum of sunlight by minor constituents in the middle atmosphere, high-energy particles over the Polar Regions and South Atlantic Anomaly, etc.