After several delays, SpaceX’s Falcon Heavy rocket is ready to launch the X-37B spaceplane for the US Space Force today (Dec. 28), and you can probably watch the action live.

Falcon Heavy is scheduled to lift off from Launch Complex-39A at NASA’s Kennedy Space Center in Florida in a window that will open at 8:07 PM ET (0107 GMT, December 28).

SpaceX announced on Sunday morning, December 10, that the first flight delay would be 24 hours. SpaceX later delayed the launch of its X-37B spaceplane on Monday, December 11, by at least 24 hours due to space issues. A new launch date was announced on Tuesday, December 12, and was tentatively set for Wednesday, December 13, but the launch was delayed again due to “ground system checks,” as SpaceX officials published on X. The company has scheduled its next launch for December 28.

The X-37B is a spaceplane that has flown on various secret long-duration missions into space, but it is not clear why it was launched on the larger Falcon Heavy rather than the Falcon 9 that SpaceX had previously launched.

Modernization of the launch vehicle may be related to mass. The X-37B has a cargo bay to house equipment and experiments and can carry an auxiliary payload that requires the additional lift capacity of the Falcon Heavy.

The uncertainty here is not surprising; Most details of the X-37B missions are classified. However, USSF-52 is carrying at least one unclassified experiment: NASA’s Project Seeds 2, which will test the effects of radiation and long spaceflight on plant seeds.

Each successive X-37B mission was longer than the previous one, with the final orbital march lasting 908 days. This mission, called OTV-6, landed in November 2022. When Falcon Heavy launches on Sunday, it will be the rocket’s ninth mission to date. This will also be the fifth flight of side thrusters supporting this special mission; The duo recently launched NASA’s Psyche probe in October this year.