(Florida Today) - A classified spy satellite is on its way to orbit after a 9:15 a.m. blastoff from Cape Canaveral Air Force Station atop a Delta IV Heavy rocket.

Liftoff from Launch Complex 37 came after three aborted attempts earlier in the morning, the first at 6:13 a.m., due to a faulty battery voltage reading and issues with two propellant valves. 

But a patient United Launch Alliance team resolved each problem and pulled off the launch several hours into the window on a perfectly clear morning. 

The 232-foot rocket blasted off for the first time with upgraded main engines beneath three first-stage boosters, each providing an extra 39,000 pounds of thrust over the earlier version.

The engines fired properly, three rust-colored boosters separated and a second stage engine ignited as planned.

After the payload fairing separated, ULA blacked out its launch broadcast at the National Reconnaissance Office's request. 

The launch was the sixth by a Delta IV Heavy, and the 20th overall by the Delta IV family since 2002. 

It was the third launch of an NRO satellite planned within five months, and the second in just over a week from the Cape. The next one will launch from California.