RECAP STORY: A companion to the world's most powerful private Earth-imaging satellite rocketed into space today from the U.S. west coast atop an Atlas 5 to double the amount of high-resolution imagery available on the commercial market and satisfy the demands of customers clamoring for more.

Read our launch story.

2:45 p.m. local (2245 GMT)
A video replay of today's launch is posted here.
1:23 p.m. local (2123 GMT)
Centaur has executed its three-minute-long Earth-escape burn, entering a solar orbit for a safe and permanent disposal. This method of boosting rocket stages out of Earth orbit has been used several times in the past.
1:07 p.m. local (2107 GMT)
"A launch like this takes teamwork and dedication across the 30 SW and our mission partners," said Lt. Col. Eric Zarybnisky, 4th Space Launch Squadron commander at Vandenberg.

"Our mission assurance technicians and engineers have worked hand-in-hand with United Launch Alliance over this extended campaign going over critical procedures and tasks to ensure this launch is successful."

1:05 p.m. local (2105 GMT)
The next Atlas 5 rocket launch from Vandenberg is expected in January for the National Reconnaissance Office.

But several missions are planned from Cape Canaveral between now and then. First up will be the launch of a next-generation U.S. civil weather observatory next Saturday, Nov. 19.

1:00 p.m. local (2100 GMT)
This was the 137th successful Atlas program launch in a row spanning more than two decades and the 66th for an Atlas 5.
12:58 p.m. local (2058 GMT)
MISSION SUCCESS is declared in today's commercial satellite launch performed by the Atlas 5 rocket from Vandenberg.

"This flawless launch was the result of extraordinary teamwork between the 30th Space Wing and our United Launch Alliance partner following the extensive fires on Vandenberg in September," said Col. Chris Moss, Vandenberg's commander and today's launch decision authority.

"What this team has accomplished in such a short time is absolutely amazing. Hundreds of people worked tirelessly over the past weeks to make this happen."

12:56 p.m. local (2056 GMT)
T+plus 2 hours, 26 minutes. The last of the cubesats, RAVAN, has been released from the Centaur upper stage!

All of the ENTERPRISE cubesat deploys have been completed, launching seven tiny technology demonstration missions to Earth orbit today. This NRO-sponsored rideshare took advantage of excess performance on the Atlas 5 rocket to carry the cubesats in addition to the primary WorldView 4 payload.

United Launch Alliance has successfully launched 62 cubesats through the company's 112 flights to date.

ULA recently selected student-built cubesats from the University of Texas at El Paso, the University of Louisiana at Lafayette, Purdue University and the University of Michigan for free launches into space aboard Atlas 5 rockets in the company's first-ever cubesat challenge.

12:53 p.m. local (2053 GMT)
T+plus 2 hours, 23 minutes. The third deploy operation has been performed for the ENTERPRISE cubesats.
12:45 p.m. local (2045 GMT)
T+plus 2 hours, 15 minutes. Confirmation that the second cubesat batch -- Aerocube 8C and 8D -- has been spring-ejected.
12:42 p.m. local (2042 GMT)
T+plus 2 hours, 12 minutes. The first cubesat deploy sequence has been performed.
12:00 p.m. local (2000 GMT)
T+plus 90 minutes. The vehicle is passing 377 miles over the North Pole, traveling at 16,923 mph.
11:37 a.m. local (1937 GMT)
T+plus 67 minutes. After flying over the South Pole, the Centaur upper stage is crossing Africa at this time. The rocket is circling the world in a 98-degree inclination orbit.
11:07 a.m. local (1907 GMT)
"Congratulations to the entire mission team. ULA is honored to celebrate the successful launch of the WorldView 4 satellite for DigitalGlobe and Lockheed Martin," said Gary Wentz, ULA vice president of Human and Commercial Services.

"This morning's Atlas 5 launch delivered the WorldView 4 satellite into near sun-synchronous orbit during a flawless flight. ULA is proud to have launched the entire constellation of DigitalGobe's satellites and served in an essential role to get this revolutionary capability to orbit."

10:57 a.m. local (1857 GMT)
T+plus 27 minutes. Today's flight of the Centaur upper stage is not over. About two hours from now, seven tiny cubesats will be deployed from carrier boxes as part of a National Reconnaissance Office-sponsored rideshare. This particular mission is called ENTERPRISE.

They are performing various technology demonstrations for U.S. national laboratories and academia.

Deployments will occur in four batches starting at T+plus 2 hours, 12 minutes, followed three minutes later by the second, then the third at T+plus 2 hours, 22 minutes and the final release at T+plus 2 hours, 25 minutes.

Then, the Centaur will perform an Earth-escape burn for a safe disposal into solar orbit.

10:50 a.m. local (1850 GMT)
T+plus 19 minutes, 28 seconds. SPACECRAFT SEPARATION! The WorldView 4 commercial Earth-observing spacecraft has been released from the United Launch Alliance Atlas 5 rocket, completing today's ascent from Vandenberg Air Force Base in California. The satellite has begun its solo flight to orbit pole-to-pole about 380 miles up in space.
10:48 a.m. local (1848 GMT)
T+plus 18 minutes. A good orbit has been achieved.
10:46 a.m. local (1846 GMT)
T+plus 15 minutes, 19 seconds. MECO. Centaur main engine cutoff has occurred following the single burn of the RL10 engine needed to inject the WorldView 4 spacecraft into polar orbit.
10:44 a.m. local (1844 GMT)
T+plus 14 minutes. All parameters from the Centaur are reported normal as the burn continues. The first stage performance was nominal too.
10:42 a.m. local (1842 GMT)
T+plus 12 minutes. The RL10 engine is consuming the liquid oxygen and liquid oxygen loaded into the vehicle just two hours ago.
10:41 a.m. local (1841 GMT)
T+plus 11 minutes. About five minutes remain in this burn of Centaur's single Aerojet Rocketdyne RL10 engine.
10:40 a.m. local (1840 GMT)
T+plus 10 minutes. The vehicle is 301 miles in altitude, continuing to power into orbit.
10:39 a.m. local (1839 GMT)
T+plus 9 minutes. Centaur performance is reported right on target.
10:37 a.m. local (1837 GMT)
T+plus 7 minutes. The rocket is tracking along the planned flight path.
10:36 a.m. local (1836 GMT)
T+plus 6 minutes. Proper first stage performance has been reported from the launch team.
10:35 a.m. local (1835 GMT)
T+plus 5 minutes. Centaur engine readings look good as this burn gets underway.
10:35 a.m. local (1835 GMT)
T+plus 4 minutes, 35 seconds. The two halves of the 14-foot-diameter Atlas 5 rocket nose cone encapsulating the satellite have separated.
10:34 a.m. local (1834 GMT)
T+plus 4 minutes, 28 seconds. Centaur has ignited! The RL10C-1 engine is up and running at full thrust to power the WorldView 4 spacecraft into orbit.
10:34 a.m. local (1834 GMT)
T+plus 4 minutes, 17 seconds. The Atlas 5's Common Core Booster has been jettisoned, completing the first stage of flight, and the Centaur upper stage's liquid hydrogen and liquid oxygen systems are being readied for engine start.
10:34 a.m. local (1834 GMT)
T+plus 4 minutes, 7 seconds. BECO. Booster Engine Cutoff is confirmed as the RD-180 powerplant on the first stage completes its burn. Standing by to fire the retro thrusters and separate the spent stage.
10:34 a.m. local (1834 GMT)
T+plus 3 minutes, 45 seconds. Atlas now weighs just a quarter of what it did at liftoff.
10:33 a.m. local (1833 GMT)
T+plus 3 minutes, 10 seconds. The RD-180 main engine continues to fire normally, burning a mixture of highly refined kerosene and liquid oxygen.
10:33 a.m. local (1833 GMT)
T+plus 2 minutes, 50 seconds. Reaction control system has been activated.
10:33 a.m. local (1833 GMT)
T+plus 2 minutes, 30 seconds. Everything still looking good on the first stage as the rocket powers downrange on the thrust being produced by the main engine.
10:32 a.m. local (1832 GMT)
T+plus 2 minutes, 20 seconds. Atlas now weighs half of what it did at liftoff, burning propellant at a rate of nearly 2,000 pounds per second.
10:32 a.m. local (1832 GMT)
T+plus 1 minutes, 45 seconds. The RD-180 main engine continues to fire normally, burning a mixture of highly refined kerosene and liquid oxygen.
10:32 a.m. local (1832 GMT)
T+plus 95 seconds. Now passing through the region of maximum aerodynamic pressure on the vehicle as its accelerates through the dense lower atmosphere.
10:31 a.m. local (1831 GMT)
T+plus 80 seconds. Mach 1. All looks good aboard the 189-foot-tall rocket.
10:31:33 a.m. local (1831:33 GMT)
T+plus 60 seconds into the mission.
10:31 a.m. local (1831 GMT)
T+plus 30 seconds. Pitch, yaw and roll maneuvers are complete, putting the Atlas 5 thunders away from the Central Coast with its RD-180 engine burning.
10:30:45 a.m. local (1830:45 GMT)
T+plus 15 seconds. The vehicle has cleared the tower at Space Launch Complex 3-East at Vandenberg and begun maneuvers to the flight heading.
10:30:33 a.m. local (1830:33 GMT)
LIFTOFF! Liftoff of the Atlas 5 rocket for DigitalGlobe, seeing a better world through the WorldView 4 imaging spacecraft!
10:30:13 a.m. local (1830:13 GMT)
T-minus 20 seconds. "Go Atlas", "Go Centaur" "Go WorldView 4" was just called by launch team during a final status check.
10:29:53 a.m. local (1829:53 GMT)
T-minus 40 seconds. Centaur's liquid oxygen and liquid hydrogen tanks are stable at flight pressures.
10:29:33 a.m. local (1829:33 GMT)
T-minus 1 minute until the launch. Range is GREEN.
10:29:03 a.m. local (1829:03 GMT)
T-minus 90 seconds. The safety system has been armed.
10:28:43 a.m. local (1828:43 GMT)
T-minus 1 minute, 50 seconds. Liquid oxygen and liquid hydrogen propellant topping to the Centaur upper stage is being secured.
10:28:38 a.m. local (1828:38 GMT)
T-minus 1 minute, 55 seconds. The launch sequencer has been commanded to start.
10:28:33 a.m. local (1828:33 GMT)
T-minus 2 minutes. The Atlas first stage and Centaur upper stage are now switching from ground power to internal batteries.
10:28:03 a.m. local (1828:03 GMT)
T-minus 2 minutes, 30 seconds. The first stage RP-1 kerosene fuel tank and the liquid oxygen have stepped up to proper flight pressure levels.
10:27:33 a.m. local (1827:33 GMT)
T-minus 3 minutes. The Atlas first stage liquid oxygen replenishment is being secured so the tank can be pressurized for launch.
10:26:43 a.m. local (1826:43 GMT)
T-minus 3 minutes, 50 seconds. The ground pyrotechnics have been enabled.
10:26:33 a.m. local (1826:33 GMT)
T-minus 4 minutes and counting. Clocks have resumed for the final minutes of today's countdown to launch the Atlas 5 rocket carrying the WorldView 4 satellite payload.
10:25:33 a.m. local (1825:33 GMT)
Countdown clocks will resume in one minute.
10:24 a.m. local (1824 GMT)
The ULA launch director has given the formal approval to press onward with the countdown.
10:23 a.m. local (1823 GMT)
All systems are reported "go" to continue with the countdown for liftoff at 10:30 a.m. The clocks will resume from this hold at 10:26 a.m.
10:21 a.m. local (1821 GMT)
Standing by for the final readiness check to be conducted. The launch team will be polled for a GO or NO GO to proceed with the count.
10:20:33 a.m. local (1820:33 GMT)
Now 10 minutes from launch.

Today marks the 66th flight for Atlas 5, born of the Air Force's competition to develop next-generation Evolved Expendable Launch Vehicles. In its previous 65 missions since debuting in August 2002, the Atlas 5 has flown 25 flights dedicated to the Defense Department, 14 commercial missions, 13 for the National Reconnaissance Office and 13 for NASA.

10:15 a.m. local (1815 GMT)
Here's a look at some stats about today's mission. This will be:
10:12 a.m. local (1812 GMT)
The WorldView 4 spacecraft is switching to internal battery power for launch. The Lockheed Martin-built satellite has a dry mass of 4,477 pounds and a launch weight of 5,479 pounds fully fueled.
10:10 a.m. local (1810 GMT)
Harris Corp., which built the camera system on WorldView 4, says the primary mirror was manufactured to an accuracy of 1/1000th of a human hair.
10:05 a.m. local (1805 GMT)
This is the fifth DigitalGlobe sub-meter resolution imagery satellite to fly since 2007. All five missions have been boosted to orbit by United Launch Alliance Delta 2 and Atlas 5 rockets from Vandenberg.
10:01 a.m. local (1801 GMT)
Weather is observed GO and forecast GO for launch.

There is a 100 percent chance of acceptable conditions for today's launch window with no areas of concern.

9:57 a.m. local (1757 GMT)
Liquid oxygen and liquid hydrogen tanks are at flight level.
9:56:33 a.m. local (1756:33 GMT)
T-minus 4 minutes and holding. The countdown has entered the planned hold to give the launch team a chance to review all systems before pressing ahead with liftoff.
9:55 a.m. local (1755 GMT)
T-minus 5 minutes and counting. Standing by to go into the final built-in hold that will last for 30 minutes.
9:50 a.m. local (1750 GMT)
The workhorse Centaur upper stage has flown in various configurations for decades. For this launch, the stage will use one Aerojet Rocketdyne-built RL10C-1 liquid oxygen/liquid hydrogen engine that develops a thrust of about 22,890 pounds.

The stage is 41.5 feet in length and 10 feet it diameter. It also houses the navigation unit that serves as the rocket's guidance brain.

9:44 a.m. local (1744 GMT)
The fuel-fill sequence for the first stage main engine is underway.
9:40 a.m. local (1740 GMT)
WorldView 4 will join sister-craft WorldView 3 in providing best-in-class 30cm imagery from space. Atlas 5 launched WorldView 3 in 2014.
9:35 a.m. local (1735 GMT)
The Atlas 5 rocket's rigid body first stage is known as the Common Core Booster. The CCB replaced the "balloon" pressure-stabilized stage used by previous Atlas vehicles.

It is equipped with the RD-180 liquid-fueled main engine. This liquid oxygen/kerosene powerplant is a two-thrust chamber, two-nozzle engine.

As the CCB's name suggests, the stage is common and is used in all the various configurations of the Atlas 5 family. The booster stage is 106.6 feet long and 12.5 feet diameter.

9:30:33 a.m. local (1730:33 GMT)
Now 60 minutes from launch. The 720,000-pound Atlas 5 rocket now stands fueled for flight and activities are proceeding toward a liftoff at 10:30:33 a.m. local Time.

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9:18 a.m. local (1718 GMT)
The liquid hydrogen tank in the Centaur upper stage just reached the 96 percent level. Topping is now beginning.
9:14 a.m. local (1714 GMT)
Fast-filling of the first stage liquid oxygen has been completed. Topping mode is now underway.
9:09 a.m. local (1709 GMT)
The Centaur liquid hydrogen tank is 40 percent loaded so far. The cryogenic propellant will be consumed with liquid oxygen by the stage's Aerojet Rocketdyne-made RL10 engine.
9:04 a.m. local (1704 GMT)
Now beyond the three-quarters level of liquid oxygen on the first stage.
9:01 a.m. local (1701 GMT)
Centaur liquid oxygen has reached flight level.
9:00:33 a.m. local (1700:33 GMT)
Now 90 minutes from liftoff. Fueling operations remain in work for the launch time of exactly 10:30:33 a.m. local.

Today's available launch window extends to 11:45:21 a.m. local (1845:21 GMT) from Vandenberg Air Force Base in California.

8:58 a.m. local (1658 GMT)
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.
8:51 a.m. local (1651 GMT)
First stage liquid oxygen tank is passing the 40 percent mark. Chilled to Minus-298 degrees F, the liquid oxygen will be used with RP-1 kerosene by the RD-180 main engine on the first stage during the initial minutes of flight today. The 25,000 gallons of RP-1 were loaded into the rocket earlier.
8:40 a.m. local (1640 GMT)
Centaur liquid oxygen is topping to flight level.
8:37 a.m. local (1637 GMT)
The first stage liquid oxygen loading is transitioning from slow-fill to fast-fill mode.
8:35 a.m. local (1635 GMT)
The Centaur liquid oxygen tank is 75 percent full now.

And the chilldown conditioning of liquid hydrogen propellant lines 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.

8:29 a.m. local (1629 GMT)
Half of the Centaur liquid oxygen tank has been filled so far.
8:16 a.m. local (1616 GMT)
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.

8:14 a.m. local (1614 GMT)
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.

8:05 a.m. local (1605 GMT)
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.
8:00:33 a.m. local (1600:33 GMT)
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 10:30:33 a.m. local time (1830:33 GMT) from Vandenberg Air Force Base in California.

Today's available launch window extends to 10:45:21 a.m. local (1845:21 GMT).

7:58 a.m. local (1558 GMT)
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 underway a short time from now.

7:55 a.m. local (1555 GMT)
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.
7:40 a.m. local (1540 GMT)
And a reminder that if you will be away from your computer but would like to receive occasional countdown updates, sign up for our Twitter feed to get text message updates on your cellphone. U.S. readers can also sign up from their phone by texting "follow spaceflightnow" to 40404. (Standard text messaging charges apply.)
7:30 a.m. local (1530 GMT)
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 the 10:30 a.m. local time (1:30 p.m. EST; 1830 GMT) 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.

7:17 a.m. local (1517 GMT)
Workers are leaving the pad area in advance of today's propellant loading and launch of the Atlas 5 rocket.
7:14 a.m. local (1514 GMT)
In the pre-fueling weather update, the marine layer and fog remains off the coast. Skies are clear over Vandenberg. Currently, there are no weather constraints to speak of.
6:15 a.m. local (1415 GMT)
The 8-million-pound mobile service tower has been retracted from around the Atlas 5 rocket, revealing the 19-story-tall vehicle for liftoff at 10:30 a.m. local time today.

The ground crews are getting the gantry's doors closed, plus finishing the final buttoning up of pad equipment before all workers clear the pad for the remainder of the countdown.

5:40 a.m. local (1340 GMT)
Rollback of the launch pad's service gantry is underway. This is a major milestone in today's countdown, getting the mobile tower retracted to uncover the Atlas 5 rocket.

The structure's internal crane was instrumental in bringing the rocket stages and payload together. And now the fully assembled Atlas 5 is being unveiled for its 66th launch, the 12th to originate from Vandenberg.

5:22 a.m. local (1322 GMT)
A readiness poll of the team has verified all systems are GO for retraction of the gantry at Space Launch Complex 3-East this morning.
4:50 a.m. local (1250 GMT)
The mobile service tower is being jacked up in preparation to roll.
4:35 a.m. local (1235 GMT)
A check of the current weather shows it is a clear morning at Vandenberg and there's a 90 percent chance of favorable conditions at liftoff time for the Atlas 5 rocket from California today.

There are no constraints to proceeding with mobile service tower rollback in about an hour. That will reveal the rocket to the elements, allowing the vehicle to be fueled and launched.

3:33 a.m. local (1133 GMT)
Atlas and Centaur have been powered up. Guidance system testing is next.
2:30:33 a.m. local (1030:33 GMT)
Clocks have begun ticking for today's flight by the Atlas 5 rocket from Vandenberg Air Force Base in California to deploy the WorldView 4 commercial satellite into space.

As the countdown gets started, the launch team will power up the rocket to conduct standard pre-flight tests and ready the vehicle.

Rollback of the mobile service tower from around the rocket is expected in about three hours. Once the gantry is removed, crews at the pad will make preparations to systems and equipment before the site is cleared of all personnel for fueling.

Supercold liquid oxygen begins flowing into the Centaur upper stage around 8:15 a.m., followed by the Atlas first stage. Liquid hydrogen fuel loading for Centaur will be completed a short time later.

A final 30-minute built-in hold is scheduled when clocks hit the T-minus 4 minute mark. That will give the team a chance to finish any late work and assess the status of the rocket, payload, Range and weather before proceeding into the last moments of the countdown.

Liftoff remains targeted for the exact moment of 10:30:33 a.m. local time (1:30:33 p.m. EST; 1830:33 GMT).

LRR: Countdown clocks will begin ticking in the middle-of-the-night Friday morning to ready an Atlas 5 rocket at America's western spaceport to launch a commercial Earth-imagery observatory.

The Launch Readiness Review today formally gave approval to proceed into countdown operations at Vandenberg Air Force Base in California to deploy the WorldView 4 satellite for DigitalGlobe.

Friday's liftoff is targeted for 10:30 a.m. local time (1:30 p.m. EST; 1830 GMT) at the opening of a 15-minute launch opportunity.

A live launch webcast can be viewed on this page.

Air Force meteorologists, as of this morning, now give 90 percent odds that the weather will allow the launch to occur. High pressure has been dominant over the region for the past several days, keeping a weather system to the northwest. At launch time Friday, the forecast calls for mostly clear skies with just some high-level cirrus, light south‐southeasterly winds of 5 to 8 knots and temperatures between 67 and 72 degrees F.

"Team V is thrilled to be launching again following the devastating wildfires we experienced in September. We are excited to launch the Atlas 5 WorldView 4 mission from Vandenberg's Western Range and are looking forward to a safe and successful mission," said Col. Chris Moss, 30th Space Wing commander at Vandenberg and the launch decision authority.

It will be the 12th Atlas 5 to fly from Vandenberg.

The launch countdown begins at 2:30 a.m. local time for the start of an eight-hour sequence to prepare the launch pad and rocket for flight.

This is United Launch Alliance's 112th flight, the 9th just this year, and the company's 19th for a commercial client.

PREVIEW: The belated launch of a powerful Earth-imaging satellite that will take the highest resolution pictures in the market, postponed by an unprecedented wildfire near the pad, is scheduled to fly on Friday.

Read our full story.

360 VR: DigitalGlobe’s 360 virtual reality preview of Friday’s WorldView 4 satellite launch atop a United Launch Alliance Atlas 5 rocket from Vandenberg Air Force Base, California. Liftoff is scheduled for 10:30 a.m. local time to reach a sun-synchronous polar orbit more than 380 miles above Earth.

See the interactive video.