SpaceX on Monday morning successfully launched a Falcon 9 rocket from NASA’s Kennedy Space Center after Sunday’s planned launch was scrubbed over a sensor issue.

The rocket, which blasted off from the historic Launch Complex 39A at 7:15 a.m., is delivering a top-secret NROL-76 satellite into orbit for the U.S. National Reconnaissance Office.

The federal agency, which develops and maintains spy satellites, said it surveys potential security threats to the U.S. by tracking terrorists and monitoring the development of nuclear weapons abroad.

Five minutes after the launch, SpaceX landed the first stage of the rocket at Cape Canaveral Air Force Station's Landing Zone 1, officials said.

It was the company's fourth zone landing and the 10th overall successful landing of the first stage booster.

Spectator Stephen Marr said watching the launch was thrilling.

“I think it is good for SpaceX that they are able to get these contracts,” Marr said. “It has been ULA only for so long.”

Marr said he values competition in the space industry.

“It is good to see it competed for,” he said. “(To) see SpaceX just have that extra revenue stream to do all the awesome things that they say they are going to do.”