Watch a live view of the Atlas 5 launch pad with countdown audio (members only)

The United Launch Alliance Delta 4 rocket, standing 217 feet tall and weighing 900,000 pounds, unleashes 1.8 million pounds of thrust from its main engine and four side-mounted boosters at 8:18 p.m. EDT Saturday (0018 GMT Sunday) to launch the ninth Wideband Global SATCOM satellite for U.S. military and allied communications.

A year after a launch mishap left Orbital ATK’s Cygnus supply ship without a ride to the International Space Station, company officials say the cargo delivery system is on the verge of a comeback, thanks to deals with United Launch Alliance and a decision to redesign its Antares booster with new rocket engines.

Two million pounds of firepower successfully launched a behemoth Delta 4-Heavy rocket and a top-secret eavesdropping surveillance satellite into space Saturday, embarking on a taxing climb directly into geosynchronous orbit 22,300 miles above the Earth to deploy one of the pinnacles of U.S. intelligence-gathering.