Europe's Ariane 5 rocket has set a new benchmark for a commercial launch - lifting into orbit a two-satellite payload weighing 9.4 tonnes.
The immense, 50m-long vehicle powered away from Kourou in French Guiana at 1929 local time (2229 GMT).
The Astra 1L and Galaxy 17 platforms it put in space will deliver TV and other services to Europe and North America.
Friday's mission represented the second launch of the year for the Ariane 5 and its 32nd flight overall.
The launch was delayed by a day because of poor weather over the spaceport on Thursday.
The rocket is the workhorse of Europe's commercial launch service, operated by the French-based Arianespace company.
In its heavy-lift, or ECA, configuration, the vehicle produces 13,000 kilonewtons of thrust at launch - equivalent to 20 Concorde jets at take-off.
Watching the launch in Kourou was US space agency (Nasa) Administrator Dr Mike Griffin.
The Nasa chief came to see the rocket that will begin to supply the International Space Station later this year.
Europe is preparing a new cargo ship called the Automated Transfer Vehicle (ATV), which will carry 7.5 tonnes of experimental equipment, spare parts, food, air and water to astronauts working on the orbiting outpost.
The ATV is designed to ride into space on top of an Ariane 5.