The 100th flight by United Launch Alliance took off Friday for deployment of a sophisticated geomobile communications satellite to bridge the digital divide in Mexico while extending the rocket company's unparalleled record of success in launching $80 billion in space assets.

Read our launch story.

“The quality and reliability of the Atlas 5 is unparalleled, and today it delivered on a critical step toward bringing next-generation mobile telecommunications services to Mexico,” said Steve Skladanek, president of Lockheed Martin Commercial Launch Services.

“The placement of Morelos 3 into orbit is vital to an effective MEXSAT constellation, and partnering with ULA, we were able to help the customer achieve that mission.”

“Congratulations to Lockheed Martin Commercial Launch Services and Mexico’s Ministry of Communications and Transportation on today’s successful delivery of the Morelos 3 satellite into orbit, providing advanced telecommunications throughout Mexico,” said Jim Sponnick, ULA vice president, Atlas and Delta Programs.

“Today was an especially proud day for our team as we launched our 100th successful one-at-a-time mission since ULA was formed in 2006. Congratulations to the entire team including our many mission partners on this unprecedented achievement.”

The next Atlas 5 rocket launch from Cape Canaveral is planned for Dec. 3 on a commercial cargo run to the International Space Station.

For ULA, the company's next mission is six days away on Oct. 8 when an Atlas 5 is launched from Vandenberg Air Force Base in California on the classified National Reconnaissance Office NROL-55 flight.

MISSION SUCCESS DECLARED by United Launch Alliance officials. This was the 128th successful Atlas program launch in a row spanning more than two decades and the 57th for an Atlas 5.

T+plus 2 hours, 52 minutes. SPACECRAFT SEPARATION! The Centaur upper stage has deployed the Morelos 3 for the Mexican Satellite System and the Ministry of Communications and Transportation.

T+plus 2 hours, 51 minutes. The second burn by Centaur inserted the rocket into another precise orbit as targeted. The vehicle is in an orbit of approximately 2,982 by 22,239 statute miles at 27 degrees inclination.

T+plus 2 hours, 49 minutes. MECO 2. Centaur has completed its second burn of the day to raise the orbit's low point for the Morelos 3 spacecraft into a high-perigee geosynchronous transfer orbit. It was a planned 51-second firing by the Centaur's single Aerojet Rocketdyne RL10C engine.

T+plus 2 hours, 48 minutes. Ignition! The Centaur's single RL10C engine has re-ignited to finish the climb into a highly elliptical geosynchronous transfer orbit.

T+plus 2 hours, 47 minutes. Liquid hydrogen and liquid oxygen system prestarts are underway.

T+plus 2 hours, 46 minutes. Centaur getting into its pressurization sequence.

T+plus 2 hours, 43 minutes. Five minutes away from the burn.

T+plus 2 hours, 41 minutes. Centaur is reorienting to the proper position for the next engine firing.

T+plus 2 hours. All parameters from the Centaur are reported normal as the coast continues.

T+plus 1 hour, 8 minutes. Now 6,818 miles above the Indian Ocean.

VIDEO REPLAY of today's Atlas 5 rocket launch with Morelos 3.

T+plus 30 minutes. Centaur is more than 1,000 miles in altitude as it coasts away from Earth in a preliminary parking orbit of 112 by 19,700 statute miles.

We will pause our live updates at this time. Check back at 9:10 a.m. EDT (1310 GMT) for confirmation of the second Centaur burn and deploy of the Morelos 3 satellite to complete today's mission.

T+plus 20 minutes. A good and proper parking orbit has been achieved.

T+plus 18 minutes, 20 seconds. MECO 1. Centaur's main engine has shut down following its first burn today, achieving orbit around Earth. The rocket will coast in this orbit for about 2.5 hours before the RL10 engine re-ignites to boost the orbit's low-point and then deploy the satellite.

T+plus 17 minutes, 10 seconds. Everything looking normal with one minute to go in this burn.

T+plus 16 minutes. Now over 20,000 mph.

T+plus 15 minutes, 30 seconds. RL10 engine parameters still look good.

T+plus 14 minutes, 30 seconds. The rocket traveling over 18,000 mph.

T+plus 14 minutes. Centaur remains on course and looking good.

T+plus 13 minutes, 17 seconds. Centaur is orbital.

T+plus 12 minutes, 15 seconds. About six minutes are left in this burn of Centaur.

T+plus 11 minutes, 30 seconds. Speed now 16,000 mph.

T+plus 10 minutes. All systems reported stable as the Centaur fires to reach an initial Earth orbit.

T+plus 9 minutes. Centaur performance is reported right on target.

T+plus 7 minutes, 45 seconds. The rocket is tracking right down the planned flight path.

T+plus 7 minutes. Good first stage performance.

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

T+plus 4 minutes, 37 seconds. The two halves of the 14-foot-diameter Atlas 5 rocket nose cone encapsulating the spacecraft have separated.

T+plus 4 minutes, 31 seconds. Centaur has ignited! The RL10C-1 engine is up and running at full thrust to power the vehicle into orbit.

T+plus 4 minutes, 21 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.

T+plus 4 minutes, 12 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 3 minutes, 30 seconds. Main engine continues to burn well.

T+plus 2 minutes, 45 seconds. Reaction control system has been activated.

T+plus 2 minutes, 35 seconds. Atlas continues tracking on course.

T+plus 2 minutes, 15 seconds. Vehicle systems looking good.

T+plus 2 minutes, 10 seconds. Both of the Aerojet Rocketdyne-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 minutes, 45 seconds. The RD-180 main engine continues to fire normally, burning a mixture of highly refined kerosene and liquid oxygen.

T+plus 93 seconds. Solid rocket booster burnout has occurred. But the spent motors will remain attached to the first stage for a few seconds, until the Atlas 5 reaches a point where the airborne dynamic pressure reduces to an allowable level for a safe jettison.

T+plus 60 seconds. The period of maximum dynamic pressure is being experienced by the rocket as we are one minute into the ascent of the Mexican Morelos 3 mobile communications satellite.

T+plus 47 seconds. Mach 1.

T+plus 30 seconds. The vehicle is heading on a flight azimuth of 104 degrees.

T+plus 15 seconds. Pitch, yaw and roll maneuvers are underway as the Atlas 5 thunders away from Cape Canaveral with its RD-180 engine and twin solid rocket boosters burning.

LIFTOFF! Liftoff of the 100th United Launch Alliance flight and the Morelos 3 satellite to bridge the digital divide in Mexico.

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. Range is green.

T-minus 90 seconds. The 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 carrying Morelos 3. Liftoff is set to occur at 6:28 a.m. EDT.

The launch team has been polled again and approval given for liftoff at 6:28 a.m. EDT (1028 GMT).

The rocket recycle is complete. Readiness poll coming up at 6:21 a.m. EDT.

Range is GO.

"Boat. Heading to chasing it out," ULA CEO Tory Bruno says of the hold.

The launch team is recycling systems back to the status at T-minus 4 minutes and holding.

NEW LAUNCH TIME. Liftoff has been retargeted for the end of the window at 6:28 a.m. EDT (1028 GMT).

Today's available launch opportunity of Morelos 3 extends to 6:28 a.m. EDT (1028 GMT).

HOLD due to Range problem! Clock has stopped at T-minus 51 seconds.

T-minus 90 seconds. The 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 carrying Morelos 3. Liftoff is set to occur at 6:08:30 a.m. EDT.

Countdown clocks will resume in one minute.

The ULA launch director has given the permission to fly today.

Polling of the team by Atlas launch conductor has occurred. All systems are reported "go" to continue with the countdown for liftoff at 6:08:30 a.m. EDT.

No problems being reported by the launch team. Countdown continues to sit in the hold period at T-minus 4 minutes, waiting for the launch window to open at 6:08:30 a.m. EDT.

Standing by for the launch team readiness polls in 10 minutes.

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

• The 639th launch for Atlas program since 1957
• The 345th Atlas launch from Cape Canaveral
• The 228th mission of a Centaur upper stage
• The 205th use of Centaur by an Atlas rocket
• The 47th Atlas 5 launch from Cape Canaveral
• The 461st production RL10 engine to be launched
• The 6th RL10C-1 engine launched
• The 63rd flight of the RD-180 main engine
• The 57th launch of an Atlas 5 since 2002
• The 12th commercial mission for an Atlas 5
• The 87th Evolved Expendable Launch Vehicle flight
• The 100th United Launch Alliance flight overall
• The 49th Atlas 5 under United Launch Alliance
• The 37th 400-series flight of the Atlas 5
• The 5th Atlas 5 to fly in the 421 configuration
• The 3rd MEXSAT program launch
• The 1st MEXSAT launch on Atlas
• The 1st Mexican satellite on Atlas 5
• The 6th Atlas 5 launch of 2015

The Morelos 3 satellite nestled inside the nose of the Atlas 5 rocket is switching to internal power for launch.

Weather remains GO for liftoff based on the current conditions and expected to stay favorable for a 6:08 a.m. EDT launch today. Odds have improved to 90 percent.

Thirty minutes from liftoff.

T-minus 4 minutes and holding. The countdown has entered the planned 30-minute hold to give the launch team a chance to review all systems and assess the weather before pressing ahead with liftoff.

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

Now 40 minutes till launch.

United Launch Alliance, the incumbent leader in U.S. rocketry, goes for its 100th flight today, a milestone nine years in the making after eclectic missions to Mars, the moon and Jupiter, and deployments of commercial, military and reconnaissance spacecraft.

Read our full story.

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

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 in August 2011 and dispatched the car-sized Curiosity rover on the Mars Science Lab mission in November 2013.

Today marks the 57th flight for Atlas 5, born of the Air Force's competition to develop next-generation Evolved Expendable Launch Vehicles. In its previous 56 missions since debuting in August 2002, the Atlas 5 has flown 22 flights dedicated to the Defense Department, 12 for NASA, 11 with spy satellites for the National Reconnaissance Office. and 11 commercial missions with communications and Earth-observing spacecraft.

Current check of the weather shows all rules are GO at this time.

Now 60 minutes from liftoff, weather permitting. Fueling of the Atlas rocket with cryogenic liquid oxygen and liquid hydrogen is complete as the countdown continues as planned for a liftoff at 6:08:30 a.m. EDT (1008:30 GMT).

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

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

The first stage liquid oxygen has reached the 80 percent level.

Centaur's liquid hydrogen tank is 30 percent full. The cryogenic propellant will be consumed with liquid oxygen by the stage's Aerojet Rocketdyne-made RL10 engine.

Launch of the Atlas 5 rocket is just 90 minutes away. Watching showers moving down the coastline to the Cape, however.

If you are heading out to the beach or Port Canaveral to watch the launch, sign up for our Twitter feed to get occasional countdown 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.)

And if you are need tips on picking a good viewing spot, check out this authoritative guide on where to go.

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.

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

Upper stage liquid oxygen has reached flight level.

First stage liquid oxygen tank is 30 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-half minutes of flight today. The 25,000 gallons of RP-1 were loaded into the rocket last night.

The Centaur liquid oxygen tank reached the 96 percent level. The topping off process is starting now.

The first stage liquid oxygen flow rate is switching 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 12,700 gallons of the cryogenic propellant.

Now three-quarters full on Centaur liquid oxygen.

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

The chilldown 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 49,000 gallons of cryogenic oxidizer for the RD-180 main engine.

The Centaur liquid oxygen tank has reached the 20 percent mark.

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 provide the thrust to put Morelos 3 into the proper orbit.

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 2 hours and counting! The launch countdown is continuing on schedule for today's flight of the Atlas 5 rocket to deploy the Morelos 3 satellite.

Clocks have one more built-in hold planned at T-minus 4 minutes. During that pause the final "go" for launch will be given. All remains targeted for liftoff at 6:08:30 a.m. EDT (1008:30 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.

After briefing his team on procedures before entering into the final two hours of the countdown, the launch conductor at the Atlas Spaceflight Operations Center just held a pre-fueling readiness poll. All console operators reported a "ready" status.

The ULA launch director also voiced approval for proceeding with the countdown.

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

All weather rules are now GO.

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The early portion of the countdown has been going well. There are no technical issues being reported in the count and activities are on schedule. Crews just departed the launch pad following completion of all hands-on work this morning.

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 6:08:30 a.m. EDT (1008:30 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. This hold will last for 30 minutes. The final hold is scheduled to occur at T-minus 4 minutes.

In the pre-fueling weather briefing to mission managers, odds for the launch window stand at 70 percent favorable. The main concern that meteorologists are watching is cumulus clouds.

Right now, showers just east of the launch pad are drifting northward over the Atlantic. This has caused the cumulus cloud rule to go RED for the time being.

The launch time outlook calls for scattered low- and high-level clouds, offshore showers, good visibility, northerly winds of 5 gusting to 10 knots and a temperature of 77 degrees F.

The countdown has begun for launch of the Atlas 5 rocket to haul Mexico's Morelos 3 mobile communications satellite into orbit.

Clocks are picking up the seven-hour sequence of work that will prepare the booster, payload and ground systems for blastoff at 6:08:30 a.m. EDT (1008:30 GMT).

The launch team will begin powering up the rocket to commence standard pre-flight tests. Over the subsequent few hours, final preps for the Centaur's liquid oxygen and liquid hydrogen systems will be performed, along with a test of the rocket's guidance system and the first stage propulsion and hydraulic preps, internal battery checks and testing of the GPS metric tracking system used to follow the rocket as it flies downrange, plus a test of the S-band telemetry relay system.

A planned hold begins when the count reaches T-minus 120 minutes. Near the end of the hold, the team will be polled to verify all is in readiness to start fueling the rocket for launch.

Supercold liquid oxygen begins flowing into the Centaur upper stage, followed by the first stage filling. Liquid hydrogen fuel loading for Centaur will be completed a short time later.

A final hold is scheduled at the T-minus 4 minute mark. That pause will give everyone 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.

The launch window extends 20 minutes to 6:28 a.m. EDT (1028 GMT).

Traveling to the launch pad this afternoon, an Atlas 5 rocket has taken its position at Complex 41 to be fueled and readied for blastoff before daybreak Friday.

The United Launch Alliance Atlas 5 vehicle, equipped with two strap-on solid-propellant boosters for added performance, will launch Mexico's Morelos 3 satellite at 6:08:30 a.m. EDT (1008:30 GMT). The available launch window extends to 6:28 a.m. EDT.

Boeing built the 11,685-pound mobile communications spacecraft for the Secretaria de Comunicaciones y Transportes of Mexico.

The booster was wheeled out aboard a mobile launcher platform, emerging from the hangar where the rocket's two stages and the payload were integrated over the past few weeks.

The slow drive from the 30-story Vertical Integration Facility to the launch pad used a pair of specially-made “trackmobiles” to carry the rocket's 1.4-million pound launching platform along rail tracks for the 1,800-foot trip.

The 195-foot-tall rocket will launch the Morelos 3 satellite into geosynchronous transfer orbit. Deployment of the payload occurs nearly three hours into flight.

The rocket is flying the 421 vehicle configuration. The version features two stages, two solids and a 14-foot-diameter, 42-foot-long aluminum nose cone. It is powered off the launch pad by an RD AMROSS RD-180 main engine and Aerojet Rocketdyne solids. The Centaur upper stage has an Aerojet Rocketdyne RL10C-1 cryogenic engine.

Countdown clocks begin ticking Thursday night, seven hours before launch, leading to activation of the rocket, final testing and system preps. Fueling will be underway by 4 a.m. EDT.

There is a 70 percent chance of acceptable weather for the launch opportunity, with winds the main concern.

The launch time outlook calls for scattered low- and high-level clouds, good visibility, northerly winds of 12-20 knots and a temperature of 78 degrees F.

The Atlas 5 rocket is emerging from the vehicle assembly building en route to the launch pad for liftoff early tomorrow morning.

All systems are GO for Friday's predawn blastoff of a commercial Atlas 5 rocket from Cape Canaveral to deploy a Mexican telecommunications satellite into orbit.

Mission managers held the Launch Readiness Review on Wednesday and gave approval to proceed with the rocket's rollout to the launch pad.

That transfer from the vehicle assembly building to the pad at Complex 41 is scheduled for just after 5 p.m. EDT on Thursday.

The launch countdown starts around 11 p.m. EDT Thursday for the start of a seven-hour sequence to prepare the rocket for flight.

Friday's 20-minute launch window opens at exactly 6:08:30 a.m. EDT (1008:30 GMT).

Weather forecasters continue to indicate a 70 percent chance of favorable conditions. Liftoff winds have become the main concern.

The outlook calls for scattered low- and high-level clouds, good visibility, northerly winds of 17 gusting to 22 knots and a temperature of 75 degrees.

PREVIEW: Desperately needing a successful deployment to modernize the communications infrastructure for its citizens, Mexico is counting on the Atlas 5 rocket to safely launch a new satellite Friday.

Mexico was burned by a Russian Proton rocket failure in May that destroyed one of its communications satellites. Now, a duplicate spacecraft is poised for launch from the U.S.

Named Morelos 3, the craft is headed for geosynchronous orbit 22,300 miles above Earth to provide 3G+ cellular voice, data, Internet and video services for Mexican national security, civil and humanitarian efforts over the next 15 years to land, sea and air terminals and smartphones.

Read our full story.