Japan · ISAS / U Tokyofirst
February 11, 1970
Ohsumi — Japan becomes the fourth space-faring nation
Lambda 4S Launcher No. 5 stood on its rail at Kagoshima Space Center on the afternoon of 11 February 1970, pointed out over the Pacific from the Ohsumi Peninsula. The University of Tokyo team behind it had been here four times before, between 1966 and 1969, and each time the little rocket had failed. At 1:25 p.m. local time the fifth attempt thundered away from the coast, carrying the hopes of a nation whose rocketry program had begun with pencil-sized test vehicles only fifteen years earlier.
By superpower standards the Lambda 4S barely qualified as a launch vehicle. It stood 16.5 metres tall, weighed 9.4 tonnes at ignition, burned solid propellant in all four stages, and carried no active guidance at all; engineers flew it with a gravity-turn technique, a choice shaped in part by domestic political sensitivities about guided rockets and missiles. The payload was equally modest: Ohsumi, a roughly 24-kilogram capsule named for the peninsula below, carrying little more than thermometers, accelerometers and radio transmitters powered by a small silver oxide-zinc battery.
Two and a half hours of silence followed while the satellite circled the planet. Then, at 3:56 p.m., the antennas at Uchinoura picked up Ohsumi's beacon returning from its first revolution, and Japan became the fourth nation to orbit a satellite on its own rocket, after the Soviet Union, the United States and France, and the first in Asia. The triumph was brief and long at once. Higher-than-expected temperatures drained the battery within about fifteen hours, but the silent satellite kept circling for 33 years, finally burning up over North Africa on 2 August 2003.
Mission Data
Launch
11 Feb 1970, 13:25 JST, Kagoshima Space Center
Launch vehicle
Lambda 4S-5, four-stage all-solid, unguided
Satellite mass
approx. 24 kg
Orbit
350 × 5,140 km, 31° inclination, 145 min period
Signal lifetime
14–15 hours
Reentry
2 Aug 2003, over North Africa
Key Facts
Success came on the fifth try: the Lambda 4S failed four consecutive times between September 1966 and September 1969 before L-4S-5 finally reached orbit.
The rocket carried no active guidance system and was flown with a gravity-turn technique, a constraint shaped partly by Japanese political concerns that guided rockets could be seen as missile technology.
Unexpectedly high temperatures killed the battery within about 15 hours, yet the silent satellite kept orbiting for 33 more years before burning up on 2 August 2003.
The milestone was achieved not by a national space agency but by the University of Tokyo's Institute of Space and Aeronautical Science, effectively a university project.
Japan beat China to orbit by just ten weeks; the world's fourth and fifth space-faring nations both arrived in the spring of 1970.
Why It Mattered
Ohsumi proved that orbit was no longer the exclusive province of superpowers with ballistic missile programs. A university institute working with miniature solid rockets had reached space independently, legitimizing Japan's space establishment and leading directly to the Mu rocket family and the ISAS deep-space science tradition that later produced missions like Hayabusa. It also opened the era in which Asia became a permanent presence in spaceflight, with China following only ten weeks later.
Rlandmann, CC BY-SA 3.0, via Wikimedia Commons
Official source
