Sea Launch is counting down to the blastoff of a new DISH Network broadcasting satellite early Wednesday from the equatorial Pacific Ocean.

The Odyssey launch platform and the Sea Launch Commander control ship arrived at the launch site over the weekend after a two-week journey from Home Port in Long Beach, Calif.

Engineers began a 72-hour countdown, and the Zenit 3SL rocket was erected on the launch pad Monday.

Spaceflight Now visited Sea Launch one week before Odyssey set sail to begin this launch campaign. See our exclusive photo gallery here and an overview of Sea Launch operations here.

Liftoff of the Zenit 3SL rocket is on tap for 0521 GMT (1:21 a.m. EDT) Wednesday, or around dusk at the company's launch site along the equator at 154 degrees west longitude.

The 200-foot-tall launcher, including parts from Ukraine, Russia and the United States, will spend an hour guiding the EchoStar 11 television broadcasting satellite into orbit.

The Zenit's first stage, propelled by an RD-171 main engine, will boost the rocket to an altitude of more than 43 miles during the first two-and-a-half minutes of the mission. The second stage's RD-120 main engine will ignite at that point to continue the flight.

After the rocket clears the thick lower layers of the atmosphere, the payload fairing will be jettisoned from around the EchoStar 11 payload at the 3-minute, 48-second point.

The rocket's second stage will separate from the Russian Block DM-SL upper stage eight-and-a-half minutes after liftoff. The upper stage's engine is programmed to fire about ten seconds later.

The first burn of the Block DM-SL will deliver the rocket and payload to a temporary parking orbit after a five-minute firing.

The upper stage will coast through space for 30 minutes before igniting again to propel EchoStar 11 into a geosynchronous transfer orbit.

The 6-minute, 38-second burn will inject the spacecraft into an orbit stretching from a low point of about 466 miles to a high point of about 22,143 miles. The rocket is targeting a final orbital inclination of zero degrees.

EchoStar 11 will be deployed from the Zenit's upper stage about one hour after launch, completing Sea Launch's role in the mission.

Officials expect to acquire the first signals from the 12,150-pound satellite about ten minutes later.

Built by Space Systems/Loral of Palo Alto, Calif., EchoStar 11 will join the fleet of satellites beaming television programming to more than 13.78 million subscribers across North America.

"There is a great deal of anticipation as we gear up for the EchoStar 11 launch," said Rohan Zaveri, vice president of space programs for DISH Network.

The launch will mark the fourth mission of the year for Sea Launch. The company expects two more Sea Launch missions this year. Up to two more flights of the company's Land Launch subsidiary are also on the books to round out 2008.