We are moving through this morning’s countdown and everything remains on track for a liftoff at 7:05 a.m. EST, including the weather. We’ll have the final launch forecast shortly, followed by a 15-minute built-in hold at T-4 minutes that will set the stage for the terminal countdown phase.
Launch polls will be conducted during this hold to clear the way for liftoff. Orion will switch over to its own battery power then the final “go/no-go” call will be made. After that, the Delta IV’s three core stage engines will ignite and rev up to 2 million pounds of thrust.
The Delta IV Heavy and Orion will clear the tower in just a few seconds to begin a carefully choreographed climb skyward. The core stages on either side of the rocket will burn their propellants and fall away at T+3minutes, 56 seconds. The central core stage will continue for another 94 seconds as the rocket and spacecraft climb higher and pick up more speed. The first stage will fall away and the second stage will take over to put Orion into an initial orbit of 115 miles by 552 miles.