Forging a new constellation of ultra-secure communications satellites that will ring the globe to link the president with military forces anywhere on the planet, an Atlas 5 rocket roared to space Friday to continue putting the pieces in place for the warfighter.

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The next Atlas launch is scheduled for June 18 from the Cape. That flight will deploy a classified spy satellite payload for the National Reconnaissance Office on the NROL-38 mission using an Atlas flying in its most-basic 401 configuration.

"ULA is proud to serve alongside our mission partners and privileged that the Air Force entrusts the ULA team to deliver critical national security capability to orbit for our soldiers, sailors, airman and Marines around the world," said Jim Sponnick, United Launch Alliance's vice president for Mission Operations.

"Through our focus on attaining Perfect Product Delivery, ULA remains dedicated to providing reliable, cost-effective launch services while continuing our unwavering commitment to 100 percent mission success. Today's successful launch was the 60th since ULA was formed just over five years ago and we congratulate the AEHF team on this important step toward delivering these critical protected communications capabilities."

Ground controllers have established communications with the newly-launched AEHF 2 satellite and confirmed the craft is operating properly in orbit to begin its 14-year mission.

Over the next couple of weeks, the spacecraft will conduct three firings of its liquid apogee engine to raise the orbit's low point toward geosynchronous altitude. The twin power-generating solar arrays then get unfurled to stretch 89 feet tip-to-tip in preparation for 90 days of Hall Current Thruster burns to finish circularizing the altitude at 22,300 miles and reducing the inclination to 4.8 degrees.

Once in geosynchronous orbit about 100 days from now, the two antenna-laden wings of the satellite will be extended and exhausting testing begins. About 217 days after launch, control of the spacecraft will be transferred to the 14th Air Force.

T+plus 51 minutes, 18 seconds. SPACECRAFT SEPARATION! The Centaur upper stage has deployed the Defense Department's second Advanced Extremely High Frequency satellite into orbit following today's launch from Cape Canaveral.

T+plus 50 minutes, 15 seconds. One minute away from releasing the payload.

T+plus 49 minutes, 30 seconds. The thermal roll is nulling out.

T+plus 48 minutes. The vehicle is more than 2,900 miles in altitude.

T+plus 46 minutes, 30 seconds. The vehicle is 11,000 miles downrange from the launch pad.

T+plus 44 minutes. Current altitude is 2,220 miles and climbing.

T+plus 43 minutes. All remains nominal aboard the launch vehicle.

T+plus 42 minutes. Current altitude is 1,890 miles and climbing.

T+plus 40 minutes. Centaur is operating well with good battery voltages and tank pressures. Telemetry from the rocket is being routed back to the Cape via NASA's Tracking and Data Relay Satellite System.

T+plus 39 minutes. The vehicle is soaring above the Indian Ocean as it climbs away from the planet. Currently 1,400 miles in altitude.

T+plus 36 minutes. The upper stage continues in its thermal conditioning roll while quietly coasting in this orbit before releasing the satellite.

T+plus 34 minutes. The rocket has flown over Africa. Current altitude is 725 miles and climbing.

T+plus 32 minutes. The successful supersynchronous transfer orbit achieved today stretches from 138 statute miles at its lowest point to over 31,210 statute miles at its highest and inclined 20.6 degrees to the equator.

T+plus 30 minutes. Centaur is turning itself to the proper orientation for releasing the payload.

T+plus 29 minutes. Although the Centaur has finished firing, the rocket won't immediately deploy the payload. That milestone moment will wait about 23 minutes as the rocket crosses Africa and Madagascar, eventually flying within communications range of the Diego Garcia tracking station on an island in the Indian Ocean.

Release of the payload from the rocket to complete the launch is expected at T+plus 51 minutes, or 3:33 p.m. EDT.

T+plus 27 minutes, 54 seconds. MECO 2. Main engine cutoff confirmed. Centaur has completed its second burn of the afternoon!

T+plus 26 minutes, 30 seconds. Centaur's RL10 engine continues a good firing.

T+plus 25 minutes, 45 seconds. Bus and battery voltages, tank pressures and other system measurements look good.

T+plus 25 minutes, 30 seconds. About two minutes are left in the burn to reach the planned supersynchronous transfer orbit.

T+plus 24 minutes. The engine is burning well. This is a planned five-and-a-half-minute firing by the Centaur's single Pratt & Whitney Rocketdyne RL10 engine.

T+plus 23 minutes. Vehicle acceleration is smooth.

T+plus 22 minutes, 10 seconds. Ignition and full thrust! The Centaur's single RL10 engine has re-ignited to accelerate the AEHF payload into the planned deployment orbit.

T+plus 20 minutes, 45 seconds. Centaur is getting pressurized again in preparation for the next engine burn.

T+plus 19 minutes, 55 seconds. Current velocity is 17,875 mph.

T+plus 19 minutes. The flight path is taking the vehicle over the equatorial Atlantic Ocean, just off the western coast of Africa. Here's the planned track map.

T+plus 18 minutes. Centaur's onboard systems are stable in this coast period continues.

T+plus 17 minutes. A good orbit has been achieved, right on the mark.

T+plus 16 minutes, 30 seconds. The rocket is performing its turn to the proper position for the next engine firing.

T+plus 16 minutes. That first burn by Centaur inserted the rocket into an orbit with a high point of 560 statute miles, a low point of 115 statute miles and inclination of 27.49 degrees.

T+plus 15 minutes, 40 seconds. All vehicle parameters still reported normal.

T+plus 14 minutes, 1 second. MECO 1. Centaur's main engine has shut down following its first burn today, achieving a preliminary orbit around Earth. The rocket will coast in this orbit for about 8 minutes before the RL10 engine re-ignites.

T+plus 13 minutes, 45 seconds. Centaur systems remain in good shape as the rocket nears orbit.

T+plus 13 minutes, 15 seconds. Everything looking normal on Centaur and RL10 engine with one minute to go in this burn.

T+plus 12 minutes, 45 seconds. Centaur remains on course and looking good. The vehicle is speeding along at over 16,000 mph.

T+plus 11 minutes, 20 seconds. RL10 engine parameters still look good.

T+plus 10 minutes, 15 seconds. About four minutes are left in this burn of Centaur.

T+plus 9 minutes, 35 seconds. The rocket is 178 miles in altitude, some 1,468 miles downrange and traveling at 14,750 mph.

T+plus 9 minutes. The RL10 continues to perform well, burning liquid hydrogen and liquid oxygen propellants.

T+plus 8 minutes, 45 seconds. Centaur is 176 miles in altitude, 1,250 miles downrange from the launch pad, traveling at 14,250 mph.

T+plus 8 minutes. All systems reported stable as the Centaur fires to reach an initial Earth orbit.

T+plus 7 minutes. The rocket is performing a planned roll to improve the link with NASA's orbiting Tracking and Data Relay Satellite System.

T+plus 6 minutes, 15 seconds. The rocket is tracking right down the planned flight path.

T+plus 5 minutes, 30 seconds. Now 130 miles in altitude, 540 miles downrange from the launch pad, traveling at 12,800 mph.

T+plus 5 minutes. Centaur engine readings look good as this burn gets underway.

T+plus 4 minutes, 38 seconds. Centaur has ignited! The RL10 engine is running at full thrust for its first of two planned firings today.

T+plus 4 minutes, 27 seconds. The Atlas 5's Common Core Booster first stage has been jettisoned, and the Centaur upper stage's liquid hydrogen and liquid oxygen systems are being readied for engine start.

T+plus 4 minutes, 22 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.

T+plus 4 minutes. Good engine throttle profile reported at 80.7 percent thrust.

T+plus 3 minutes, 39 seconds. The two-halves of the Atlas 5 rocket nose cone encapsulating the AEHF 2 spacecraft have separated, exposed the satellite to space. Also jettisoned was the Forward Load Reactor, a two-piece deck that rings the Centaur stage to support the bulbous fairing during launch.

T+plus 3 minutes, 15 seconds. The RD-180 main engine continues to fire smoothly, burning a mixture of highly refined kerosene and liquid oxygen.

T+plus 2 minutes, 50 seconds. The reaction control system has been activated.

T+plus 2 minutes, 20 seconds. RD-180 is performing nominally at 95 percent throttle.

T+plus 2 minutes, 3 seconds. Boosters one, two and then three have jettisoned. The Aerojet-made solid rocket motors have successfully separated from the Atlas 5, having completed their job of adding a powerful kick at liftoff.

T+plus 1 minute, 33 seconds. Solid rocket booster burnout has occurred. But the spent motors will remain attached to the first stage for a brief while, until the Atlas 5 reaches a point where the airborne dynamic pressure reduces to an allowable level for a safe jettison.

T+plus 1 minute, 10 seconds. The RD-180 has revved back to full throttle.

T+plus 60 seconds. The launcher is departing Cape Canaveral to give the second Advanced Extremely High Frequency communications satellite a 51-minute ride to orbit.

T+plus 45 seconds. Mach 1.

T+plus 40 seconds. The main engine is throttling down to 76 percent of rated thrust to ease the stresses on the vehicle during transit through the lower atmosphere.

T+plus 15 seconds. Pitch, yaw and roll maneuvers are underway as the Atlas 5 points itself to arc over the Atlantic Ocean en route to a supersynchronous transfer orbit. The RD-180 engine and three solid rocket boosters are up and burning!

LIFTOFF! Liftoff of Atlas 5 with AEHF 2, forging a new ultra-secure communications satellite system for the United States government. And the vehicle has cleared the tower!

T-minus 20 seconds. "Go Atlas" and "Go Centaur" was just called by launch team during a final status check.

T-minus 40 seconds. Centaur's liquid oxygen and liquid hydrogen tanks are stable at flight pressures.

T-minus 1 minute. Now 60 seconds away from launching the 30th Atlas 5 rocket.

T-minus 90 seconds. The rocket's safety system has been armed.

T-minus 1 minute, 45 seconds. Liquid oxygen and liquid hydrogen propellant topping to the Centaur upper stage is being secured.

T-minus 1 minute, 55 seconds. The launch sequencer has been commanded to start.

T-minus 2 minutes. The Atlas first stage and Centaur upper stage are now switching from ground power to internal batteries.

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.

T-minus 3 minutes. The Atlas first stage liquid oxygen replenishment is being secured so the tank can be pressurized for launch.

T-minus 3 minutes, 50 seconds. The ground pyrotechnics have been enabled.

T-minus 4 minutes and counting. Clocks have resumed for the final minutes of today's countdown to launch the Atlas 5 rocket with second Advanced Extremely High Frequency satellite, one of the Defense Department's most sophisticated and critical spacecraft.

The ULA launch director and Air Force mission director have given their "go" to resume the countdown as scheduled.

Polling of the team by Atlas launch conductor just occurred. All systems are "go" for an on-time liftoff today at 2:42 p.m. EDT.

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.

Here's a look at some stats about today's mission. This will be:

• The 612th launch for Atlas program since 1957
• The 324th Atlas to occur from Cape Canaveral
• The 201st mission for Centaur upper stage
• The 178th use of Centaur by an Atlas rocket
• The 30th launch of an Atlas 5 since 2002
• The 26th Atlas 5 to occur from the Cape
• The 22nd Atlas 5 under United Launch Alliance
• The 49th Evolved Expendable Launch Vehicle flight
• The 9th Atlas 5 launch overseen by the Air Force
• The 10th 500-series flight of the Atlas 5
• The 2nd Atlas 5 to fly in the 531 configuration
• The 2nd Atlas launch with AEHF payload
• The 2nd Atlas launch of 2012

A direct link to our text updates.

The AEHF 2 spacecraft nestled inside the nose cone of the Atlas 5 rocket is switching to internal power for launch.

T-minus 4 minutes and holding. The countdown has entered the planned 10-minute hold to give the launch team a chance to review all systems before pressing ahead with liftoff.

The first stage liquid oxygen tank and Centaur's liquid oxygen and liquid hydrogen tanks are reported at flight level.

T-minus 5 minutes. Standing by to go into the final built-in hold.

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Upper level winds are favorable today as well.

The official forecast for today's two-hour launch window extending from 2:42 to 4:42 p.m. EDT continues to predict good weather for an on-time liftoff. None of the weather rules are being violated right now. However, thick clouds are drifting this way and could pose a constraint to fly later in the window.

The fuel-fill sequence for the first stage main engine is starting.

Thirty minutes from liftoff. The countdown clocks are heading to the T-minus 4 minute mark where a planned 10-minute hold will occur. Launch of Atlas 5 remains scheduled for 2:42 p.m. EDT.

Atlas 5 represents the culmination of evolution stretching back several decades to America's first intercontinental ballistic missile. At the dawn of the space age, boosters named Atlas launched men into orbit during Project Mercury and became a frequent vehicle of choice to haul civil, military and commercial spacecraft to orbit.

Topped with the high-energy Centaur upper stage, Atlas rockets have been used since the 1960s to dispatch ground-breaking missions for NASA, including the Surveyors to the Moon, Mariner flights to Mars, Venus and Mercury, and the Pioneers that were the first to visit Jupiter and beyond.

In its newest era, the Atlas 5 rocket sent the Mars Reconnaissance Orbiter to the red planet in 2005, propelled the New Horizons probe toward Pluto and the solar system's outer fringes in 2006, doubled up with the dual Lunar Reconnaissance Orbiter and LCROSS impactor to the Moon in 2009, hurled Juno to Jupiter last August and dispatched the car-sized Curiosity rover on the Mars Science Lab mission in November.

Today marks the 30th flight for Atlas 5, born of the Air Force's competition to develop next-generation Evolved Expendable Launch Vehicles. In its previous 29 missions since debuting in August 2002, the tally shows nine commercial flights with communications spacecraft, nine dedicated to the Defense Department, five missions with spy satellites for the National Reconnaissance Office and six for NASA.

Pre-launch checks of the rocket's safety system have been completed.

Constructed around Lockheed Martin's A2100 satellite model with a 14-year design life, the AEHF satellites like the one being launched today feature power-generating solar panels stretching 89 feet tip-to-tip and two antenna-laden deployable wings.

What's more, the craft are nuclear-hardened to survive the effects of hellish warfare and possess built-in autonomy to resolve onboard problems while enduring hostile conditions.

They are built to follow the military's aging Milstar satellite series that provide the preeminent communications with top-level protection.

While all five Milstars remain in use, the emerging AEHF fleet will fly alongside to offer their faster data speeds and expand the capacity for secure communications across the world.

"This system is integral to our national security space architecture. It provides significantly improved protected communications capabilities for both tactical and strategic users. With the addition of a second AEHF satellite in the constellation, the nation will have a robust and resilient seven-satellite combined Milstar-AEHF constellation that will add significant protected communications capabilities for the warfighter," said John Miyamoto, Lockheed Martin's vice president for advanced programs in Global Communications Systems.

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

The liquid hydrogen tank in the Centaur upper stage just reached the 97 percent level. Topping is now beginning.

The first stage liquid oxygen tank is above 90 percent full now.

The weather odds have decreased to 60 percent favorable for today's launch window due to worries about incoming clouds moving from west to east across Florida this afternoon. But all the weather rules are "green" at the present time.

Now 60 minutes from liftoff. Fueling of the Atlas rocket with cryogenic liquid oxygen and liquid hydrogen is proceeding as planned for a liftoff at 2:42 p.m. EDT.

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

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.

First stage liquid oxygen tank is 50 percent full thus far. 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 four-and-a-quarter minutes of flight today. The 25,050 gallons of RP-1 were loaded into the rocket after rollout Wednesday.

The Centaur engine chilldown sequence is being initiated.

The first stage liquid oxygen tank has reached the 20 percent mark.

The Centaur liquid oxygen tank reached the 95 percent level. The topping off process is starting now.

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

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 12,320 gallons of the cryogenic propellant.

Centaur liquid oxygen is three-quarters loaded.

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 48,745 gallons of cryogenic oxidizer for the RD-180 main engine.

The Centaur upper stage's liquid oxygen tank is 50 percent full.

Filling of the Centaur upper stage with about 4,075 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 two firings to propel the payload -- initially into a parking orbit, then into a highly elliptical supersynchronous transfer orbit.

Now exactly two hours until launch! There are no reports of any technical problems and the current weather is acceptable.

The Centaur liquid oxygen 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.

T-minus 120 minutes and counting! The launch countdown has resumed on schedule for today's flight of the Atlas 5 rocket with the AEHF 2 secure military communications satellite.

Clocks have one more built-in hold planned at T-minus 4 minutes. That pause will last 10 minutes during which time the final "go" for launch will be given. All remains targeted for liftoff at 2:42 p.m. EDT 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.

All console operators have reported GO status during the pre-fueling readiness poll. The ULA launch director also voiced his approval for moving forward with the countdown as scheduled today.

Loading of cryogenic liquid oxygen and liquid hydrogen into the Atlas 5 rocket will be getting underway a short time from now.

The ULA launch conductor at the Atlas Spaceflight Operations Center is briefing his team on procedures before entering into the final two hours of the countdown.

The Complex 41 pad and surrounding danger area has been cleared of all workers for the remainder of the countdown.

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Now that final hands-on work has wrapped up at Complex 41, all workers are departing the pad for the remainder of the countdown.

Working in parallel with the countdown, a team of technicians has successfully removed and replaced a gaseous helium relief valve at the launch pad. All retesting has gone well and that task has wrapped up in preparation for fueling.

T-minus 2 hours and holding. The countdown has just entered the first of two planned holds over the course of the day that will lead to the 2:42 p.m. EDT launch of the Atlas 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 before fueling starts. The final hold is scheduled to occur at T-minus 4 minutes and will last for 10 minutes.

The latest weather update to mission managers shows the probabilities remain mostly favorable with a 70 percent chance of acceptable conditions during today's launch window. The opening of the window is expected to be better than later in the day due to approaching thick clouds that could be a problem.

For launch time, Air Force meteorologists are calling for some scattered low clouds at 3,000 feet, scattered mid-level clouds at 10,000 feet, a broken deck of high clouds at 24,000 feet, potentially isolated showers in the vicinity, good visibility, southeasterly winds of 12 gusting to 16 knots and a temperature around 79 degrees F.

Now entering into the final three hours of the countdown for launch at 2:42 p.m. EDT.

If you are in the local Cape Canaveral area and would like to watch today's Atlas 5 rocket launch in person, check out this authoritative viewing guide on where to go.

Hydraulic and propulsion system preps on the Atlas first stage have finished. And hold-fire checks were just performed with the Eastern Range to ensure safety personnel can hold the countdown if necessary.

The hazard area roadblocks around the launch site's safety perimeter have been established. Also, the launch team has configured the pad's water deluge system. And testing of the vehicle's guidance system is complete.

Completed in the countdown a short time ago, engineers finished pre-flight testing on the C-band system used to track the rocket as it flies downrange and checks of the vehicle's internal batteries. Currently underway, final preps to various elements of the rocket and ground facilities are being performed, as well as testing the S-band system used for telemetry relay from vehicle.

The purge system for the Centaur interstage adapter has been successfully retested following corrective work by technicians to reconfigure a manually-operated control valve on the mobile launch platform. Engineers recently completed a helium flow test to validate the entire system and the results looked nominal, officials say, clearing the way for today's launch at 2:42 p.m. EDT.

It is shaping up to be a cloudier day for this second launch attempt, forecasters report. Meteorologists will be watching for electrically charged anvil clouds from thunderstorms in the Gulf of Mexico coming over the launch site and the thickness of the local cloud cover as potential violations to the launch rules this afternoon. Overall, there is a 70 percent chance of acceptable weather.

The outlook calls for scattered clouds at 3,000 and 10,000 feet, broken high clouds at 24,000 feet, a chance isolated coastal showers, good visibility, southeasterly winds of 12 to 16 knots and a temperature around 79 degrees F.

Forecasters predict similar conditions and 70 percent odds on Saturday, if the launch is delayed again for some reason.

Technicians at Complex 41 have carried out the work to remedy the helium purge problem in ground support equipment that prevented the launch from occurring yesterday. The team will conduct a confidence-building retest of the system this morning to verify the no-flow condition on that purge to the Centaur's interstage adapter has been fully corrected.

After helium purge problem kept the Atlas 5 rocket on the pad Thursday afternoon, a second launch attempt is getting underway today to deploy a sophisticated and critical communications spacecraft for the U.S. government.

The countdown clocks just began ticking, beginning a seven-hour sequence of work that will prepare the rocket, payload and ground systems for today's blastoff at 2:42 p.m. EDT (1842 GMT).

The day's two-hour launch window stretches to 4:42 p.m. EDT.

Here's a timeline of the countdown's key events:

 HR:MM..Eastern...Event
T-6:20...7:42am...Countdown begins with rocket power up
T-5:30...8:32am...Weather briefing
T-4:55...9:07am...Start clearing assembly building area
T-4:20...9:42am...C-band tracking beacon testing
T-3:40..10:22am...S-band telemetry link checks
T-2:55..11:07am...Establish blast danger area roadblocks
T-2:20..11:42am...Weather briefing
T-2:15..11:47am...Clear the pad
T-2:00..12:02pm...T-120 minutes and holding (for 30min)
T-2:00..12:27pm...Launch conductor briefing to team
T-2:00..12:29pm...Readiness poll for fueling
T-2:00..12:32pm...Resume countdown
T-1:50..12:42pm...Centaur LOX transfer line chilldown
T-1:43..12:47pm...Begin Centaur liquid oxygen loading
T-1:30...1:02pm...Begin Atlas first stage LOX loading
T-1:25...1:07pm...Centaur LH2 transfer line chilldown
T-1:10...1:22pm...Centaur RL10 engine chilldown
T-1:02...1:30pm...Begin Centaur liquid hydrogen loading
T-0:40...1:52pm...FLight termination system final test
T-0:16...2:16pm...RD-180 engine fuel fill sequence
T-0:10...2:22pm...Weather briefing
T-0:04...2:28pm...T-4 minutes and holding (for 10min)
T-0:04...2:35pm...Readiness poll for launch
T-0:04...2:38pm...Resume countdown
T-0:00...2:42pm...LAUNCH

Read our earlier status center coverage.