The head of Russia's federal space agency arrived on Tuesday at the Kourou space center in French Guiana to oversee preparations for the much-anticipated first launch of the modernized Soyuz carrier rocket.

Parts of two Soyuz-ST rockets, to be launched this year, were delivered to French Guiana in South America in 2009. The first launch was repeatedly postponed, and the project seems to be behind schedule again as the April deadline was not met.

The Russian and French space officials are uncertain of when the launch will take place, saying only that the rocket will definitely blast off by the end of this year.

During the visit, Roscosmos head Anatoly Perminov will meet with ESA director-general Jean-Jacques Dordain and officials of the French space agency CNES, the Russian space agency said on its website.

He is also to visit the Soyuz-ST assembling facility and the launch pad of Ariane-5, the main European-made booster. He may be joined by Sergei Ivanov, Russian deputy prime minister in charge of space and defense industries, who is also expected in Kourou for a working visit on Tuesday.

Russia's Federal Space Agency Roscosmos and French satellite launch firm Arianespace signed a contract in 2008 to launch ten Russian Soyuz-ST carrier rockets from Kourou, with two launches scheduled for 2010.

However, Arianespace Chairman and CEO Jean Yves le Galle said only one Soyuz launch will be held in 2010 to take the Hylas-1 commercial satellite to orbit. The second launch from Kourou is not expected by the end of 2010.

Arianespace suffered numerous setbacks this year, mainly related to numerous delays of the recent Ariane-5 launch. In addition, the company's income dropped 71.1 million euros (over $90 million), to 1.03 billion euros (over $1.31 billion) last year.

The Kourou launch site is intended mainly for the launch of geostationary satellites. Its proximity to the Equator will enable the Soyuz-ST to put into orbit heavier satellites than those launched from Baikonur in Kazakhstan and Plesetsk in northern Russia.