10:44 p.m. EDT (0244 UTC)The Centaur liquid oxygen tank is topping to flight level. Meanwhile, first stage liquid oxygen loading is transitioning from slow-fill to fast-fill mode.
10:50 p.m. EDT (0250 UTC)The first stage liquid oxygen tank has reached the 20 percent mark.
10:55 p.m. EDT (0255 UTC)The launch team has received the "go" to begin filling the Centaur upper stage with the super-cold fuel following chilldown of the system. The Centaur holds about 12,300 gallons of the cryogenic propellant for its three engine burns during this launch.
11:02 p.m. EDT (0302 UTC)First stage liquid oxygen tank is 50 percent full thus far. The LOX will be consumed along with RP-1, a highly refined kerosene, by the RD-180 main engine on the first stage during the initial four-and-a-half minutes of flight. The 25,000 gallons of RP-1 were loaded into the rocket after rollout yesterday.
11:08 p.m. EDT (0308 UTC)Centaur's liquid hydrogen tank is 50 percent full. The cryogenic propellant will be consumed with liquid oxygen by the stage's Aerojet Rocketdyne RL10C-1 engine.
11:14 p.m. EDT (0314 UTC)The liquid hydrogen tank in the Centaur upper stage just reached the 96 percent level. Topping is beginning.
11:15 p.m. EDT (0315 UTC)This is Atlas Launch Control with 60 minutes remaining in our countdown to liftoff at 12:15 a.m. EDT (0415 UTC). Today marks the 79th flight for Atlas 5 since debuting in August 2002. The vehicle has a 100 percent mission success record for the Defense Department, NASA, the National Reconnaissance Office and commercial customers.
11:25 p.m. EDT (0325 UTC)Fast-filling of the first stage liquid oxygen tank has been completed. Topping mode is now underway to give us a fully-fueled, 1.3-million-pound rocket for flight. The cryogenics will be replenished throughout the countdown until the final minutes before launch to replace the liquid oxygen and liquid hydrogen that naturally boils away.
11:44 p.m. EDT (0344 UTC)The fuel fill sequence is beginning. This procedure releases RP-1 kerosene fuel into the RD-180 main engine in preparation for ignition.
11:46 p.m. EDT (0346 UTC)Weather is observed and forecast GO for liftoff at 12:15 a.m. EDT (0415 UTC) today, according to the countdown’s final planned briefing by Air Force weather officer Jessica Williams.
