T-4 Minutes and Holding

The launch countdown is in a T-4 minute hold. The launch team is proceeding toward launch of a United Launch Alliance Delta IV Heady rocket carrying Parker Solar Probe on a mission to the Sun.

Liftoff is scheduled for 3:31 a.m. EDT, at the beginning of a 65-minute launch window. The forecast is now at 95 percent chance for favorable weather conditions for launch.