From the beginning of the program a Zenit-3 version was proposed for geosynchronous launches using the N1/Proton Block D third stage. This had the potential of replacing the Proton in the role of geosynchronous launcher. It was considered for launch from Australia / Cape York in the 1980's. Finally a joint US-Norwegian-Ukraininan-Russian consortium was formed to launch the three stage commercial Zenit from a floating launch platform in the Pacific Ocean,
Launches: 4. Failures: 1. Success Rate: 75.00% pct. First Launch Date: 28 March 1999. Last Launch Date: 28 July 2000. Payload: 5,250 kg. to a: Geosynchronous transfer trajectory. Liftoff Thrust: 740,000 kgf. Total Mass: 471,000 kg. Core Diameter: 3.9 m. Total Length: 59.6 m. Launch Price $: 90.00 million. in 1999 price dollars.
The first Boeing Sea Launch mission. The Zenit-3SL lifted off from the Odyssey floating platform on the equator at 154 degrees West longitude. The DemoSat payload was an instrumented dynamic model of an HS-702 satellite built by Boeing Commercial Space/Kent. 13 minutes after launch, the Block DM-SL upper stage completed its first burn and entered a 180 km x 735 km x 1.2 degree parking orbit. A second burn 47 minutes after launch placed DemoSat in a 638 km x 36,064 km x 1.2 degree geostationary transfer orbit. Three hours later, a third DM-SL burn lowered the stage's perigee so that it would re-enter quickly.
Second successful Zenit-3SL flight from the Odyssey launch platform in the Pacific Ocean at 154 deg W, 0 deg N. First flight to carry a commercial payload. The satellite used its R-4D apogee engine to enter geostationary orbit at 81.6 deg W. Finally stationed at 101 deg W.
First ICO Global Communications satellite. Lost due to launch vehicle failure; was to have entered a 10,300 km x 45 deg circular orbit. ICO's satellites would carry multiple spot beams for mobile communications.
Panamsat geosynchronous communications satellite to replace PAS 5 at 58 deg W. Stationed at 58 deg W.