SpaceX’s Falcon Heavy will launch on its first commercial flight tomorrow. The rocket launch was postponed from early April due to unspecified concerns, and then postponed again just this week due to weather. But Wednesday has a clear forecast with an 80% probability of a launch, so odds are good the mission will proceed. The launch window opens at 6:35am EDT.

Falcon Heavy is a modified version of SpaceX’s standard Falcon 9 rocket, essentially made up of three Falcon 9’s strapped together