NROL-52 – Atlas V 421 (AV-075) – Канаверал SLC-41 – 15.10.2017 07:28 UTC

[tnt22]

ULA‏Подлинная учетная запись @ulalaunch 58 мин. назад

The #AtlasV #NROL52 launch countdown has entered a planned 15-minuted hold. This is the first of 2 planned holds in today's countdown.

10/06/2017 08:33 Countdown in pre-planned hold

T-minus 2 hours and holding. The countdown has just entered the first of two planned, 15-minute holds over the course of the day that will lead to the 4:03 a.m. EDT (0803 GMT) launch of the Atlas rocket. The holds give the team some margin in the countdown timeline to deal with technical issues or any work that is running behind. The final hold is scheduled to occur at T-minus 4 minutes.

[tnt22]

Spaceflight Now‏ @SpaceflightNow 47 мин. назад

As countdown progresses flawlessly, all is GO to fuel Atlas 5 rocket for #NROL52 https://spaceflightnow.com/2017/10/02/av075_journal/ ...

[tnt22]

10/06/2017 08:38

MAN STATIONS for cryogenic tanking operations.
The countdown is progressing very smoothly today, without the weather drama that occurred yesterday before fueling.

[tnt22]

ULA‏Подлинная учетная запись @ulalaunch 46 мин. назад

The team has given the Go to begin cryogenic fueling operations and we're counting down again to #AtlasV #NROL52 launch at 4:03amEDT

10/06/2017 08:45 GO for fueling

Console operators have reported READY status during the pre-fueling readiness poll. The ULA launch director also voiced his approval for moving forward with the countdown today.

The loading of nearly 66,000 gallons of cryogenic liquid oxygen and liquid hydrogen into the Atlas 5 rocket will be getting underway a short time from now.

[tnt22]

10/06/2017 08:48 Countdown running again

T-minus 2 hours and counting! The launch countdown has resumed for today's flight of the Atlas 5 rocket to deploy the clandestine NROL-52 satellite for the National Reconnaissance Office.

Clocks have one more built-in hold planned at T-minus 4 minutes. During that 15-minute pause, the final "go" for launch will be given. All remains targeted for liftoff at 4:03 a.m. EDT (0803 GMT) from Cape Canaveral's Complex 41.

In the next couple of minutes, chilldown thermal conditioning of the mobile launch platform upon which the rocket stands will begin. This is meant to ease the shock on equipment when supercold cryogenic propellants start flowing into the rocket.

[tnt22]

10/06/2017 08:55 Centaur LOX loading

Filling of the Centaur upper stage with about 4,150 gallons of liquid oxygen has begun at Cape Canaveral's Complex 41 following the thermal conditioning of the transfer pipes.

The liquid oxygen -- chilled to Minus-298 degrees F -- will be consumed during the launch by the Centaur's single RL10 engine along with liquid hydrogen to be pumped into the stage a little later in the countdown. The Centaur will perform the firings required to propel the NROL-52 spacecraft into the desired orbit today.

[tnt22]

10/06/2017 09:16

The chilldown conditioning of liquid hydrogen propellant lines at Complex 41 is starting to prepare the plumbing for transferring the Minus-423 degree F fuel into the rocket. The Centaur holds about 12,300 gallons of the cryogenic propellant.

[tnt22]

10/06/2017 09:18 Atlas LOX loading

The conditioning of the systems for the first stage liquid oxygen tank have been completed. And a "go" has been given to begin pumping supercold liquid oxygen into the Atlas 5's first stage.

The Common Core Booster stage's liquid oxygen tank is the largest tank to be filled today. It holds 48,800 gallons of cryogenic oxidizer for the RD-180 main engine.

[tnt22]

Tory Bruno‏Подлинная учетная запись @torybruno 7 мин. назад

Centaur LO2 loading complete

[tnt22]

10/06/2017 09:28

The first stage liquid oxygen loading is transitioning from slow-fill to fast-fill mode.

[tnt22]

10/06/2017 09:33 L-minus 90 minutes

Everything continues to go very smoothly and the countdown is on schedule to launch he NROL-52 classified government payload aboard Atlas 5 at 4:03 a.m. EDT (0803 GMT).

[tnt22]

10/06/2017 09:37

Weather conditions have gone RED due to clouds over the spaceport.

[tnt22]

10/06/2017 09:40 Centaur LH2 loading

Chilldown of the liquid hydrogen system has been accomplished. The launch team has received the "go" to begin filling the Centaur upper stage with the supercold fuel.

[tnt22]

10/06/2017 09:41

The Centaur engine chilldown sequence is being initiated.

[tnt22]

Launch Hazard Area - обновлена
 

[tnt22]

Airspace Closure Area - обновлена
 

[tnt22]

10/06/2017 09:47

Centaur's liquid hydrogen tank is 20 percent full. The cryogenic propellant will be consumed with liquid oxygen by the stage's Aerojet Rocketdyne-made RL10 engine.

[tnt22]

10/06/2017 10:00

The liquid hydrogen tank in the Centaur upper stage just reached the 96 percent level. Topping is beginning.

[tnt22]

10/06/2017 10:03

Now 60 minutes till Atlas launch of #NROL52, weather permitting.

[tnt22]

10/06/2017 10:10

Fast-filling of the first stage liquid oxygen tank has been completed. Topping mode is now underway.