An Arianespace heavy lift rocket is set to carry dual satellites which will offer direct to home television service for Europe over to central Asia and Japan.
Lift-off is targeted for Thursday at 5:51:07 pm EDT (21.51 GMT) -- the opening of a seventy minute launch window -- from complex 3 in Kourou, French Guiana.
Today the launch team will perform a launch rehearsal as they ready the entire launch system for Thursday. The launch vehicle will then be rolled out to its launch pad early on Wednesday and connected to fuel and power lines.
Riding a top the Ariane 5 in the payload cone will be the W3B satellite for Eutelsat at the top, and stacked below it will be Japan's BSAT-3b.
The W3B television satellite will offer broadcasting service to multiple countries from it's perch at 16 degrees East longitude in geostationary orbit. Countries in Europe, northern Africa, the Middle East and in central Asia will receive service from the 53 Ku-band and three Ka-band transponders.
The satellite on orbit will measure nearly 112 feet from its six panel t-shaped solar array to array, and nineteen feet wide.
W3B will also offer high speed Internet, data and telephone service during it's planned fifteen year life.
In contrast, the Lockheed Martin built BSAT-3b for Japan's direct to home broadcast satellite will be used for high speed programming. Supporting only 12 Ku-band transponders, the satellite will operate over 110 degrees east.
BSAT-3b measures 48 feet from solar array tip to array tip by 6.23 feet wide as it sails through space.
This will be the Ariane 5's fourth mission of 2010 and only the 53rd since it first flew in 1996.
The 165 1/2-foot Ariane 5 is fueled during ascent by a core liquid fueled engine and two strap on soild fuel boosters.
The single Vulcain 2 main engine ignites at T-0 in the count followed by the 104-foot twin boosters igniting seven seconds later.
During the rocket's climb to space, it will steer out from it's launch pad in northeastern South America and eastward out over the southern Atlantic Ocean.
Just over two minutes into the launch, the boosters will have spent their fuel at will then jettison at 5:53:22 pm EDT.
After a brief ride to orbit, the first of the satellites to be deployed will be W3B at 6:19:11 pm, as the rocket's upper stage passes through 737 miles altitude.
Nearly ten minutes later, Japan's BSAT-3b will be released at an altitude of 2084 miles high.