Video: Delta 2/SMAP pre-launch news conference

The mission will focus on proving the reusability of the rocket and not on additional flight objectives, like operating the payload bay door or reigniting the vacuum engines on the Ship upper stage. The June 5 launch window opens at 7 a.m. CDT (8 a.m. EDT (1200 UTC).

Fueled segments of the solid rocket boosters that will lift off on the first flight of NASA’s Space Launch System have arrived at the Kennedy Space Center in Florida, but officials will hold off on stacking the boosters until the SLS core stage completes a crucial test-firing later this year.

United Launch Alliance’s next-generation Vulcan rocket will lift off from the company’s existing Atlas 5 launch facilities in Florida and California, according to the company’s Vulcan program manager.