Photos: Atlas 5 rocket on the pad with WorldView 4 satellite

One of the largest satellites in the world will launch aboard America’s biggest operational booster Thursday, riding that power to a listening post 22,300 miles above the planet for its clandestine eavesdropping mission, all indications suggest.

These photos show SpaceX’s Falcon 9 rocket, with a previously-flown first stage booster, sitting on its launch pad Tuesday at Vandenberg Air Force Base in California ahead of the scheduled liftoff of the Radarsat Constellation Mission.

The United Launch Alliance Atlas 5 rocket, standing 191 feet tall and and weighing 720,000 pounds, unleashes 860,000 pounds of thrust from its main engine at 9:49:51 a.m. local time today to launch the secret NROL-79 payload for the U.S. National Reconnaissance Office from Vandenberg Air Force Base, California.