A Russian rocket Zenith-3SL bearing an American TV broadcasting satellite took off from a floating platform in the Pacific Ocean.

Mission control near Moscow said the launch had been successful, delivering the satellite into a geosynchronous orbit about 62 minutes after lift-off.

The satellite, developed by Hughes Electronic Corporation, will provide 30 extra channels for DIRECTV, the leading digital television supplier in the United States.

Earth's rotation

The three-stage rocket lifted off at 0328 GMT on Sunday from the Odyssey - a converted oil platform stationed about 1,500 miles south-east of Hawaii.

The platform's position on the equator - using the Earth's rotation to maximum effect - makes putting payloads into orbit cheaper.

This means the rocket can harness maximum benefit from the Earth's rotation, which helps catapult the payload into space.

Less fuel should be needed, making the launch less expensive. It also means heavier satellites can be carried - up to five tonnes.

Wave effect

The owners say that although the platform is low in the water, it will not be a problem unless the waves are bigger than three metres (10ft) and the wind blows harder than 45 mph (72 km/h).

When the platform is steady, the space vehicle can be wheeled out from a hangar, stood upright and fuelled with kerosene and liquid oxygen.

Odyssey departed from Long Beach, California

Officials say they have 18 further confirmed launch orders.

The charge for each launch is $40m, according to Sea Launch. Europe's Arianespace, which launches from French Guiana, charges $55m per rocket and has 70% of the world's business.