It will be the fifth launch of the Delta IV Heavy, but the first from Vandenberg, and the most powerful rocket ever to lift off from the West Coast.
The rocket, which is scheduled to launch at 1:10 p.m., is believed to be carrying a spy satellite.
The rumble of the liftoff may be heard as far as 50 miles away, and Lompoc residents are being alerted, so they won't think it's an earthquake.
This launch marks a significant milestone in our nation's space capability" said Lt. Col. Brady Hauboldt, launch director. "We've really restored a national capability for heavy lift on the Western Range, something we have not had since the last of the Titan IV-Bs flew out of Vandenberg."
Vandenberg officials say persons without prior knowledge of the launch may accidently see it with the naked eye as far away as 25 miles, while those who are specifically looking for the launch may be able to see it as far away as 50 miles without optical assistance. People using binoculars or a telescope may be able to see the launch as far away as 100 miles, provided they look at the right area of the sky at the right time.
The best place to view the launch will probably be near the south end of the base. Vandenberg officials recommend the public go to Surf Beach to view the launch, but to hear the countdown, they will need to go to the Corral Road viewing location.