Liftoff is scheduled during a launch window that opens at 6:36 p.m. and continues to 7:05 p.m. local time, with EchoStar XVII and MSG-3 being deployed during a 34-minute flight.

This will be the 63rd launch of an Ariane 5, and Arianespace’s third flight of its heavy-lift workhorse in 2012.

EchoStar XVII is a Space Systems/Loral-built 1300-series satellite platform, and is to be operated by Hughes Network Systems – delivering broadband services from geostationary orbit to consumers, businesses and government customers across North America.

MSG-3 is a weather observation spacecraft for EUMETSAT (the European Organisation for the Exploitation of Meteorological Satellites).  Produced by a Thales Alenia Space-led consortium, MSG-3 will operate in geostationary orbit – providing detailed images of Europe, Africa and the North Atlantic for use by meteorologists and national weather forecasters.