The Sea Launch project is a joint venture involving American capital and Russian hardware.

The idea is to position a floating launch pad on the equator, as far away from the Earth's spinning axis as possible, so that less fuel is needed to get into orbit, making launches cheaper.

BBC's Andrew Harding reporting from Vyborg

The BBC correspondent, Andrew Harding who has been to see the project progressing, says the sight of the huge platform - called Odyssey - which is now in the Russian port of Vyborg, in the Baltic Sea, is extraordinary.

Its owners say Odyssey is the largest construction of its kind, measuring 133m long by 67m wide.

It is expected that by mid-June it will start its trip from the Baltic Sea to the Pacific Ocean. The launch site is about 1,600km south of Hawaii.

The huge platform will work with a command ship, which will be used as a floating rocket assembly plant and mission control.

Submerged

Almost all of the platform will be submerged in the water, to give it the stability needed for a precise launch. The owners say that as long as waves do not get above 3m and wind not above 20m per second, there will be no problem.

The first rocket to be launched from Odyssey, a Ukrainian-made booster of Soviet-era design, will be shipped out to the home base aboard a special cargo vessel from St Petersburg, in readiness for a maiden launch planned for early October.

Odyssey is joining the increasingly competitive and busy satellite launch market.