UPDATE: 7:40 a.m. - SpaceX launch has been cancelled this morning due to a sensor issue. The launch has been rescheduled for Monday morning. 

ORIGINAL REPORT: After postponing a launch from a few weeks ago, SpaceX is set to launch its first military payload Sunday, a classified satellite.

SpaceX is planning to launch a Falcon 9 rocket that will carry a classified satellite for the U.S. National Reconnaissance Office.

The two-hour launch window opens at 7 a.m. Sunday. A backup launch window is scheduled for 7 a.m. Monday.

The launch was supposed to happen April 16 but was delayed.

The launch of the NROL-76 will take place from Launch Complex 39A at NASA's Kennedy Space Center. The complex was built in the early 1960s to support the Apollo program. Later, in the 1970s, it was modified to support the space shuttle program.

After the launch, SpaceX will try to land the first stage of the Falcon 9 rocket at their landing zone at Cape Canaveral Air Force Station. Residents in the area might hear a sonic boom from the landing attempt.

Friday's forecast for Sunday is supposed to be 90 degrees, sunny and breezy.

We will carry live coverage of the launch on TV (watch TV live stream — authentication required), or you can watch SpaceX's live stream here on our website.