WASHINGTON – The launch of a spy satellite aboard a SpaceX Falcon 9 was postponed for 24 hours Sunday morning after the launch company detected an issue with a sensor on the rocket’s first stage less than a minute before the scheduled liftoff.

NROL-76 mission patch. Credit: NRO
NROL-76 mission patch. Credit: NRO

 Just 52 seconds before liftoff was set to occur, SpaceX called a 24-hour hold to check out the sensor, pushing the launch to Monday’s two-hour backup window that opens at 7 a.m. Eastern.

“Standing down today due to a sensor issue; backup launch opportunity tomorrow morning,” SpaceX posted to Twitter. 

SpaceX's mission patch for the Falcon 9 NROL-76 launch. Credit: SpaceX
SpaceX’s mission patch for the Falcon 9 NROL-76 launch. Credit: SpaceX
SpaceX’s mission patch for the Falcon 9 NROL-76 launch. Credit: SpaceX

The classified payload for the mission designated NROL-76 is a satellite for the National Reconnaissance Office, SpaceX’s first mission for the spy agency. It is also the first launch since successfully launching and landing a previously-flown Falcon 9 booster March 30 on a mission for commercial satellite operator SES. 

The rocket will lift off from SpaceX’s Launch Complex 39A at Kennedy Space Center, Florida. Should the launch occur as planned Monday, the company will attempt to recover the first stage booster, landing it at Landing Zone 1 at Cape Canaveral Air Force Station.

Phillip Swarts is the military space reporter for SpaceNews. He previously covered space and advanced technology for Air Force Times, the Justice Department for The Washington Times, and investigative journalism for the Washington Guardian;...