A British mobile satellite the size of a double-decker bus is to be launched in Kazakhstan.
The launch marks the completion of a £722 million programme to increase UK-based communications company Inmarsat's broadband coverage across the world.
The six tonne satellite has already been lifted into launch position at the Baikonur Cosmodrome.
The take-off was previously delayed because of a fault discovered during testing.
An Inmarsat spokesman said: "The Proton M will carry the Inmarsat-4 F3 into geostationary orbit at 22,240 miles.
"Once tested and operational, it will provide satellite phone and mobile broadband services to North and South America at 98 degrees west.
"And together with its two sister satellites, already in orbit, the completed constellation will deliver full and seamless global coverage for our entire range of broadband mobile satellite services."