NROL-42 (SBIRS HEO-4) – Atlas V 541 (AV-072) – Ванденберг SLC-3E – 24.09.2017, 05:49 UTC

[tnt22]

ULA‏Подлинная учетная запись @ulalaunch 1 мин. назад

The #AtlasV #NROL42 countdown has just entered a planned 30-minute hold. This is the first of 2 planned holds in the countdown.

[tnt22]

09/24/2017 05:30 Countdown in pre-planned hold

T-minus 2 hours and holding. The countdown just entered the first of the planned holds over the course of the day that will lead to launch of the Atlas-Centaur rocket.

This initial pause lasts 30 minutes, giving 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.

At this time, the countdown is progressing very smoothly with no problems being worked.

[tnt22]

09/24/2017 05:40
Fueling of the Atlas 5 rocket will be getting underway shortly. Watch this ULA video for more information on the process:

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[tnt22]

Tory Bruno‏Подлинная учетная запись @torybruno 48 сек. назад

In the planned 30 min hold at T-2 hours. The board is green

[tnt22]

Spaceflight101 LIVE‏ @S101_Live 24 сек. назад

Trumpet-FO-2 satellites are designed to complement the Orion sats in Geostationary Orbit, offering favorable look angles at high latitudes.

[tnt22]

Spaceflight101 LIVE‏ @S101_Live 1 мин. назад

For some details on current eavesdropping efforts going on high above: http://spaceflight101.com/snowden-documents-reveal-mysterious-pan-satellite/ ...

Secret Endeavors of Mysterious Spy Satellite revealed in Snowden Documents - статья за 2016 г.

[tnt22]

09/24/2017 05:55

The Atlas launch conductor is briefing his team on procedures before entering into the final two hours of the countdown. A readiness check of the team members is next.

[tnt22]

Spaceflight Now‏ @SpaceflightNow 1 мин. назад

Launch team polled and all is ready for fueling Atlas-Centaur with 66,000 gallons of cryos for #NROL42 https://spaceflightnow.com/2017/09/19/av072_journal/ ... (ULA pic)


09/24/2017 05:57 GO for fueling

The launch team and all systems are "ready" to proceed with the countdown and begin fueling the Atlas 5 rocket as planned.

Loading of cryogenic liquid oxygen and liquid hydrogen into the Atlas 5 rocket will be getting started a few minutes from now.

[tnt22]

09/24/2017 05:59 Countdown running again

T-minus 2 hours and counting! The launch countdown has resumed for today's flight of the Atlas 5 rocket following the planned half-hour built-in hold.

Clocks have one more hold scheduled at T-minus 4 minutes. That pause will last 30 minutes during which time the final "go" for launch will be given.

All remains targeted for liftoff at exactly 10:29:48 p.m. local time (1:29:48 a.m. EDT; 0529:48 GMT) from Vandenberg Air Force Base in California.

[tnt22]

ULA‏Подлинная учетная запись @ulalaunch 3 мин. назад

Counting down once again! The ULA launch team has given the "GO!" to begin cryogenic fueling operations. #AtlasV #NROL42

[tnt22]

Spaceflight101 LIVE‏ @S101_Live 46 сек. назад

Now inside T-2 hours, #AtlasV is starting prop load operations with Liquid Oxygen ground systems and tank chilldown.

[tnt22]

09/24/2017 06:06

The Centaur liquid oxygen system's pad storage area has been prepped. The next step is conditioning the transfer lines, which is now beginning to prepare the plumbing for flowing the cryogenic oxidizer.

[tnt22]

Spaceflight Now‏ @SpaceflightNow 57 сек. назад

Fueling has started! Loading of 4,150 gallons of liquid oxygen now underway for Centaur stage to loft #NROL42 https://spaceflightnow.com/2017/09/19/av072_journal/ ... (ULA)

[tnt22]

ULA‏Подлинная учетная запись @ulalaunch 1 мин. назад

Beginning to load liquid oxygen into the Centaur upper stage. #AtlasV #NROL42

[tnt22]

09/24/2017 06:08 Centaur LOX loading

Filling of the Centaur upper stage with about 4,150 gallons of liquid oxygen is beginning at Vandenberg's Space Launch Complex 3 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 loaded into the stage a little later in the countdown.

[tnt22]

09/24/2017 06:13 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 flowing 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 about 48,800 gallons of cryogenic oxidizer for the RD-180 main engine.

[tnt22]

ULA‏Подлинная учетная запись @ulalaunch 25 сек. назад

Beginning to load liquid oxygen into the #AtlasV with #NROL42.

[tnt22]

09/24/2017 06:16

Now passing the 20 percent level on the Centaur liquid oxygen tank.

[tnt22]

09/24/2017 06:22

Half of the Centaur liquid oxygen tank has been filled so far.

[tnt22]

09/24/2017 06:29

The Centaur liquid oxygen tank is 75 percent full now.