The first two Soyuz rockets scheduled to lift off from the Guiana Space Center next year will take their first step toward space Saturday, beginning a transatlantic ocean voyage to a jungle spaceport instead of heading for the familiar steppes of Kazakhstan.

The MN Colibri cargo ship with two Soyuz rockets aboard. Arianespace

Components of the Soyuz ST vehicles were loaded into the MN Colibri cargo freighter this week in St. Petersburg, Russia, for the upcoming trip to the Guiana Space Center in South America.

The MN Colibri will set sail from St. Petersburg on Saturday, embarking on a journey of almost 6,000 miles to Pariacabo port in French Guiana. From there, the rocket parts will be transported by road to the European-run launch site in Kourou.

The trip will take 15 days, putting arrival in French Guiana around Nov. 22 if schedules hold.

The shipment includes parts for the Soyuz rocket's core and Fregat upper stages for two launches.

The Soyuz and Fregat are manufactured by the Samara Space Center and NPO Lavochkin, respectively.

After arriving in Kourou, the equipment will be readied in a new integration building 700 meters, or 2,300 feet, from the brand new launch pad at the northwest edge of the space center.

The three core stages of the Soyuz will be assembled horizontally much like the standardized integration process at the venerable rocket's home base at the Baikonur Cosmodrome in Kazakhstan.

Unlike operations at Baikonur, the Soyuz will be rolled to the launch pad without its Fregat upper stage or satellite payload.

Construction of the pad is in the final phases.

"The installation (of the launch pad) is 99 percent complete. We are now running the integrated tests, meaning the testing of various elements of the ground systems," said Antonio Fabrizi, head of the European Space Agency's launchers division.

The Soyuz launch pad in Kourou. Credit: Arianespace/ESA

A 174-foot-tall mobile gantry is being built to allow workers access for installation of the Fregat, payload and fairing as the Soyuz is upright on the launch pad.

Russian workers have already completed a replica of the Soyuz launch pad at Baikonur, including a similar flame trench, launch table, erector system, swing arms and four lightning towers.

"Most of the work on the launch pad is completed and we are now starting installation of the mobile gantry, which will be ready early next year. This should lead to a first launch in April or May, something like that," said Jean-Yves Le Gall, Arianespace chairman and CEO.

Arianespace, which will operate the commercial Soyuz missions, has not selected a payload for the first flight of the launcher from Kourou.

"It will be a (geosynchronous transfer orbit) satellite and we have several candidiates," Le Gall said. "We will see depending upon the availability date of the Soyuz and the satellites."

Le Gall said there are contracts for 11 future commercial Soyuz launches, including multi-spacecraft flights for Europe's Galileo navigation system and the Globalstar mobile communications satellite fleet. Four new contracts for Soyuz missions have been signed this year, according to Le Gall.

The 152-foot-tall rocket will take advantage of Earth's speedier rotation near the equator, receiving a natural boost that increases its lift capacity to about 7,000 pounds for typical communications satellite launches.

The Soyuz can only haul about 4,000 pounds to such an orbit from Baikonur.

Soyuz rockets launching from Kourou will include the upgrades of the Soyuz 2 program, such as a new digital control system and a more powerful third stage engine. Kourou flights will also use the ST-type fairing, a bulbous payload shroud with a diameter of almost 13.5 feet.