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

The $2bn Sea Launch project aims to use a giant converted oil rig, positioned on the equator, to put satellites into space relatively cheaply.

The US Federal Aviation Administration has licensed Sea Launch after safety checks. The FAA head, Jane Harvey, said: "This will be the beginning of a new and captivating period in the field of commercial space launches."

Cheaper access to space is possible if the launch site is exactly on the equator. This means the rocket can harness the maximum benefit from the Earth's rotation, to help catapult it into a geostationary space orbit.

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 launch is currently scheduled for 2218 GMT on 27 March, 1999, from a point on the equator 2,250km (1,400 miles) south of Hawaii.

The platform is called Odyssey and is a refitted, 25-year-old North Sea oil rig, measuring 133m (435ft) long by 67m (220ft) wide. It propels itself through the water but before the launch will virtually submerge in order to gain stability.

Steady platform

Safety tests have been completed

The owners say that being this low in the water 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 will be wheeled out from a hangar, stood upright and fuelled with kerosene and liquid oxygen. Ukrainian Zenit and Tsiklon booster rockets will be used.

A ship acting as the control centre is accompanying 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 and by 23 March had nearly arrived at the launch site.

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.