he "Zenit"  is a medium lift booster and its first stage was used for the "Energia" booster stap-on's. It was developed at the "Yujnoye Scientific Production Association". Flight testing began in 1985, and since becoming operational it has been used exclusively from Tyuratam for launch of ELINT satellites. In the mid-1970s, development got under way of a unique, new-generation launcher. Ecologically clean, capable at a launch weight of 459 tons of putting a satellite weighing 16 tons into orbit. "Zenit 2", 2 stage booster could launch up to 15,000 kg. or smaller payload up to 2000 km. altitude (±3.5 km., 2.5 sec., 2.5 minutes inclination). "Zenit 2" weighs 460,000 kg, can launch 12,000 kg. to 200 km. circular 90° orbit. "Zenit 3" a "Zenit 2" with the Block-D, can launch up to (4500 kg. to GTO) 1100 kg to geostationary  orbit. Possible launches from a Australian facility and using 2 solid kick motors  could  raise payload   to 3,000 kg. to   GEO (±.01 Hour, ±60-160 sec.,  ±6 min inclination). Weight on launch is 467,000 kg.  "Zenit SL" is a "Zenit 3" which gains additional payload capacity by launching near the equator. The "Zenit" first stage had a single four nozzle RD-171 engine that used