Engineers in South America finished constructing the framework of a 17-story mobile gantry for the Soyuz rocket in June, but the installation of pad systems continues in hopes of launching the Russian booster from the new facility by December, an Arianespace spokesperson said Friday.

The Soyuz launch pad gantry under construction in June. Credit: ESA/CNES/Arianespace

The schedule is tight for December because of the late construction of the Soyuz pad's mobile tower, in which the rocket's satellite payloads will be bolted atop the vehicle.

The launch pad is being built at the Guiana Space Center, a French-run spaceport at the edge of the Amazon jungle. Located in Kourou, French Guiana, the launch site has hosted nearly 200 flights of Ariane rockets since 1979.

The new Soyuz complex is about 7 miles northwest of the existing Ariane 5 launch pad.

Russian and European workers must still clad the tower with electrical cables, communications systems, cranes, work platforms, metallic siding and other equipment for rocket assembly and launch operations. That could take several more months.

The Soyuz launch pad pedestal, umbilical arms and flame trench were finished last year.

The first two Soyuz 2-1a rockets to launch from Kourou were delivered from Russia to French Guiana in November. Engineers started integrating the three-stage rocket this spring inside the freshly-built Soyuz launcher integration building.

The first Soyuz rocket is assembled in Kourou, French Guiana. Credit: Arianespace

Soyuz rocket variants have flown more than 1,700 times, but the flights from Kourou will be the first time the workhorse launchers lift off outside of Russia or the Baikonur Cosmodrome in Kazakhstan.

If workers complete the mobile gantry in time, they will move the Soyuz to the launch pad by September to begin fit checks and interface tests ensuring the facility is built to specifications.

The first Soyuz from Kourou will launch the HYLAS communications satellite for Avanti Communications of the United Kingdom.

At the beginning of 2010, Arianespace and European Space Agency officials said the Soyuz would debut sometime this summer. But delivery and assembly delays for the mobile gantry pushed the launch to September, then the 4th Quarter, and now until December.

The French Guiana pad is the first Soyuz complex to use a mobile gantry. Soyuz facilities at Baikonur and the Plesetsk Cosmodrome in Russia do not have service towers because the rockets horizontally roll out to the pad fully assembled and ready for launch.

A panorama of the Soyuz launch pad at the Guiana Space Center. Credit: Arianespace

In Kourou, Soyuz payloads will be added to the rocket vertically inside the gantry.

Managers aren't ruling out a delay to 2011, but Arianespace says there has been no decision on a specific launch date in December or on another slip into next year.

Arianespace, which sells Soyuz rockets commercially, has accumulated orders for up to 19 flights of the medium-lift launcher from Kourou and Baikonur.

The Soyuz joins the market-leading Ariane 5 rocket in Kourou, and Europe's small Vega satellite launcher will make its first flight in early 2011, giving Arianespace a toehold in all sectors of the launch industry.