Kvaerner 's Per Herbert Kristensen explains why it is beneficial to launch from the equator

The mission could herald a new era in the space business as it is designed to cut the cost of launching commercial satellites.

The three-stage rocket, built by Boeing's Russian and Ukrainian partners, lifted off at 0130 GMT on Sunday from the Odyssey - a converted oil platform stationed about 1,500 miles southeast of Hawaii.

The $2bn Sea Launch project aims to make the satellite business much cheaper by sending up all payloads from near the equator. This means the rocket can harness maximum benefit from the Earth's rotation, which helps catapult the payload into space.

The US Federal Aviation Administration (FAA) licensed Sea Launch after safety checks.

Before the launch, the FAA head, Jane Harvey, said: "This will be the beginning of a new and captivating period in the field of commercial space launches."

Space flight consultant Phillip Clarke says there are concerns over the reliability of the Zenit boosters.

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

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).

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

A ship acting as the control centre is accompanies Odyssey. It is 200m (660ft) long and was built on the Clyde in Glasgow, UK. In port, the ship is the rocket assembly area.

Odyssey departed from Long Beach, California

The ship and platform left their home port in Long Beach, California, on 11 March.

The Sea Launch consortium says it already has contracts for 18 commercial launches and could host over 60 missions by 2010.

The Hughes Space and Communications Company has awarded a contract for 10 satellite launches with an option for a further 10.

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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.