Watch conditions at Kennedy Space Center during Tropical Storm Isaias

SpaceX’s next Falcon 9 rocket ignited its nine Merlin engines at Kennedy Space Center’s launch pad 39A Thursday in a customary pre-flight test ahead of the company’s next mission, slated for Monday with a commercial South Korean-owned communications satellite.

SpaceX’s final Falcon 9 launch of the year carried a classified payload for the National Reconnaissance Office, the U.S. government’s spy satellite agency. SpaceX aborted a launch attempt Thursday morning to assess a second stage sensor reading, but the Falcon 9 successfully lifted off from the Kennedy Space Center at 9 a.m. EST (1400 GMT) Saturday. The rocket’s stage landed back at Cape Canaveral eight minutes later.

SpaceX rolled out the company’s first space-worthy Crew Dragon spacecraft and its Falcon 9 launcher to pad 39A at NASA’s Kennedy Space Center in Florida for the first time Thursday, beginning a series of fit checks before the commercial spaceship takes off on its first orbital test flight.