Live at Cape: Atlas V booster being fueled

The Atlas V's Centaur upper stage has been filled with more than 4,200 gallons of liquid oxygen, putting it at "flight level."

The LO2 is now being loaded into the rocket's common core booster, which already contains its RP-1 fuel.

Managers still expect a thunderstorm to put a "red" condition on the countdown, but not necessarily interfere with the launch.

"We do have plenty of time remaining to hopefully wait that out as this thunderstorm system moves toward the south," said George Diller, a NASA TV commentator.

Titusville residents report hearing thunder in the area.

If the 5:12 p.m. target liftoff time is not possible, additional opportunities are possible at 5:22 p.m. and 5:32 p.m.

Each window lasts one second.