Europe's Ariane 5 rocket has been in service since 1996
Arianespace, the Paris-based company which operates Europe's rocket service, has placed an order for 35 new Ariane 5 ECA launchers.
The contract signed with EADS Astrium is worth 4bn euros (£3.6bn).
The Ariane 5 ECA is one of the world's biggest rockets, and lofts scientific and commercial payloads from the Kourou spaceport in French Guiana.
Arianespace currently has a large backlog of customers wanting to put satellites in orbit.
The company expects to launch six to eight Ariane 5s this year.
Noteworthy payloads will include the Herschel and Planck space observatories, and the Terrestar-1 telecommunication satellite, which at over six tonnes will be one of the biggest commercial platforms ever put in geostationary orbit.
Arianespace also expects to start operations of the Russian Soyuz rocket from Kourou in late 2009, and perhaps even Europe's new small launcher called Vega.
The Ariane 5 was developed under the European Space Agency's launcher programme which is committed to providing member states with guaranteed access to space.
The Ariane 5 has made 42 launches since its introduction in 1996. After two early catastrophic failures, it has built a strong reputation for reliability and the accuracy of its orbital insertions.
Last year it began servicing the International Space Station by launching Europe's space freighter, the ATV.