Ohsumi (satellite)
Artist's rendition of Ohsumi in orbit. | |
| Mission type | Earth science |
|---|---|
| Operator | Institute of Space and Aeronautical Science, University of Tokyo (now part of JAXA) |
| COSPAR ID | 1970-011A |
| SATCAT no. | 04330 |
| Mission duration | 33 years, 5 months and 21 days |
| Spacecraft properties | |
| Launch mass | 24.0 kilograms (52.9 lb) |
| Power | 10.3 watt |
| Start of mission | |
| Launch date | February 11, 1970, 04:25 UTC |
| Rocket | Lambda-4S |
| Launch site | Kagoshima LA-L |
| Contractor | ISAS |
| End of mission | |
| Last contact | February 12, 1970 |
| Decay date | August 2, 2003 |
| Orbital parameters | |
| Reference system | Geocentric |
| Regime | Medium Earth |
| Eccentricity | 0.262379 |
| Perigee altitude | 350 kilometres (220 mi) |
| Apogee altitude | 5,140 kilometres (3,190 mi) |
| Inclination | 31.0 degrees |
| Period | 144.0 minutes |
| Epoch | 10 February 1970, 23:25:00 UTC |
The Ohsumi ( or Ōsumi, おおすみ) satellite, Japan’s first artificial satellite, was launched on February 11, 1970, at 04:25 UTC (Coordinated Universal Time) by the Institute of Space and Aeronautical Science (ISAS) from the Kagoshima Space Center, which is located on the Ohsumi peninsula in Japan. This location was chosen for its strategic position in coordinating eastward launches, optimizing the rocket's trajectory. The launch vehicle was the Lambda 4S-5, a rocket developed by the ISAS of the University of Tokyo. Such an achievement marks Japan as the fourth nation to independently place a satellite into orbit.
The satellite achieved an elliptical orbit with an apogee of approximately 5,150 km and a perigee of 335 km, conducting experiments to gather data on the ionosphere and testing satellite launch technologies. Although its operational life ended within hours due to power loss, Ohsumi remained in orbit for over 33 years before re-entering the atmosphere on August 2, 2003. The mission's success laid the foundation for Japan’s later achievements in space exploration, including scientific missions such as Hakucho and Hayabusa.