PARIS — Engineers will complete a series of minor adjustments on Europe’s Ariane 5 rocket to raise its payload-carrying capacity to about 9,200 kilograms to geostationary transfer orbit — compared to around 8,900 kilograms currently — by the end of 2010, the chief executive of launch services provider Arianespace said.

Jean-Yves Le Gall, who has long argued that the global commercial-launch market is oversupplied, said there may be signs already of a coming drop in demand for commercial launches.

By Arianespace’s count, 24 commercial launch contracts have been signed so far in 2009. On the face of it, this would appear to be a banner year for the industry. But only 16 of these contracts have been for new satellites. The remaining eight are for satellites that were previously booked by one launch service provider but later transferred to another.

Le Gall said Evry, France-based Arianespace, which previously had talked about raising its annual launch rate to eight Ariane 5 vehicles per year, now believes that six or seven heavy-lift Ariane 5 rockets and two or three medium-lift Soyuz vehicles will be sufficient for the market.

“We do not see a [global commercial launch] market beyond 18 to 20 satellites per year,” Le Gall said. Arianespace’s contract backlog includes 33 geostationary telecommunications satellites in addition to the company’s planned launches of European government spacecraft.

Russia’s Soyuz rocket is scheduled to begin operations from Europe’s Guiana Space Center in French Guiana, at a new pad nearing completion, in the spring of 2010. Launched from French Guiana, Soyuz will be able to place a 3,000-kilogram telecommunications satellite into geostationary transfer orbit, the destination of most commercial telecommunications spacecraft.

Squeezing additional lift capacity out of the Ariane 5 will permit Arianespace to continue its dual-launch policy by launching a 6,000-kilogram satellite together with a smaller spacecraft weighing up to 3,000 kilograms on a single vehicle.

Peter B. de Selding was the Paris bureau chief for SpaceNews.