Terminal countdown begins about three hours before the designated
liftoff time. The Boeing Launch Director receives input from NASA, the
Jet Propulsion Laboratory, and the Air Force before proceeding with the
countdown. There is a periodic release of weather balloons to determine
the force of the winds, and there is confirmation that all tracking
stations are available. Learn more about the Delta II launch vehicle by
selecting a section of the rocket at left and clicking on that section
for more detail. Learn what happens during the terminal countdown by
clicking on "View Launch Timeline" below.
