A United Launch Alliance Atlas 5 rocket boosted a classified National Reconnaissance Office payload into orbit Wednesday after a picture-perfect morning launch from Vandenberg Air Force Base northwest of Los Angeles.

The Russian-built RD-180 engine at the base of the rocket thundered to life at 12:50 p.m. EST (GMT-5; 9:50 a.m. local time), throttled up to full thrust and majestically pushed the 191-foot-tall rocket away from Space Launch Complex 3 at Vandenberg.

Riding 860,200 pounds of thrust, the Atlas 5 arced away to the south over the Pacific Ocean and accelerated toward space, bound for an orbit around Earth’s poles where spy satellites and weather stations can “see” the entire planet as it rotates below.

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Four minutes and three seconds after liftoff, the RD-180 shut down, the first stage fell away and the Aerojet-Rocketdyne RL10C-1 engine powering the Atlas 5’s second stage ignited, continuing the boost to space.

As usual with missions to launch classified military satellites, United Launch Alliance ended its launch commentary a few moments after second stage ignition “at the request of our customer.” The National Reconnaissance Office, which manages the nation’s top-secret national security payloads, provided no additional details.

A closeup view of the Atlas 5 moments after first stage engine ignition. ULA

Ted Molczan, a respected satellite tracker and analyst, believes the payload is a pair of Naval Ocean Surveillance System satellites used to track Russian and other military ships at sea. If correct, this is the eighth pair of NOSS satellites launched since 2001.

This was the 70th launch of an Atlas 5 since the booster’s debut in 2002, the second so far this year and the first of three planned for this month.

Next up for ULA is launch of a Delta 4 rocket carrying a military communications satellite from Cape Canaveral on March 8, followed by launch of an Orbital ATK Cygnus space station cargo ship on March 19, also from the Cape Canaveral Air Force Station.