Launching for the 200th time and loaded with one of its heaviest cargoes ever, the Atlas-Centaur rocket flexed its muscle and sped away from Cape Canaveral on Tuesday night with a U.S. Navy satellite for mobile communications to the military and White House.

Read our launch story.

0438 GMT (11:38 p.m. EST)
"The ULA team is honored to deliver this critical mission into orbit for the U.S. Navy and U.S. Air Force with the support of our many mission partners," said Jim Sponnick, ULA vice president, Atlas and Delta Programs.

"The MUOS 3 spacecraft is the heaviest payload to launch atop an Atlas 5 launch vehicle. The Atlas 5 generated more than two and half million pounds of thrust at liftoff to meet the demands of lifting this nearly 7.5-ton satellite.

"Today's launch was the 200th Atlas-Centaur launch – a very sincere congratulations to the many women and men responsible for the incredible success of the Centaur upper stage over the last 5 decades!"

0359 GMT (10:59 p.m. EST)
SPACECRAFT SEPARATION! The Centaur upper stage has deployed the U.S. Navy's third Mobile User Objective System satellite, dubbed MUOS 3, for a 15-year mission to provide mobile communications to U.S. military forces on the move.

Just a few minutes before separation, the Centaur completed its third burn of the day to raise the orbit's low point and reduce orbital inclination for the MUOS spacecraft. It was a planned minute-long firing by the Centaur's single Aerojet Rocketdyne RL10C engine, which was making its second flight.

0155 GMT (8:55 p.m. EST)
A video replay of tonight's launch is posted here.
0141 GMT (8:41 p.m. EST)
We will pause our live updates at this time. Check back around 11 p.m. EST for confirmation of the third Centaur burn and deploy of the MUOS 3 satellite to complete today's mission.
0139 GMT (8:39 p.m. EST)
T+plus 35 minutes. A typical Atlas 5 ascent to geosynchronous transfer orbit, the standard dropoff point for communications satellites, uses just two firings by the Centaur to achieve the highly elliptical, egg-shaped orbit to deploy the payloads. From there, the satellites use their own engines in the subsequent days to fly into the operational locations 22,300 miles above the equator.

But the sizable MUOS, at nearly 15,000 pounds, drove planners to create a three-burn launch profile for the hefty payload to use all of the available performance from the Atlas-Centaur that in turns saves the satellite's precious onboard fuel supply for maneuvering over its 15-year life.

The three burns provides 1,000 pounds greater lift capability than a conventional 2-burn geosynchronous transfer orbit.

0134 GMT (8:34 p.m. EST)
T+plus 30 minutes. The second burn by Centaur inserted the rocket into another precise orbit as targeted.
0132 GMT (8:32 p.m. EST)
T+plus 28 minutes. Centaur now begins a quiet two-and-a-half-hour coast through space, moving higher and away from the planet before the third and final burn occurs nearly 2 hours and 49 minutes into flight. Deployment of MUOS 3 from the rocket to complete the launch is expected 2 hours, 53 minutes after launch.
0130 GMT (8:30 p.m. EST)
T+plus 26 minutes, 29 seconds. MECO 2. Main engine cutoff confirmed. Centaur has completed its second burn of the day, this one taking the next step upwards to substantially increase the altitude from the previous parking to nearly geosynchronous height.
0129 GMT (8:29 p.m. EST)
T+plus 25 minutes, 45 seconds. Engine performance remains normal.
0128 GMT (8:28 p.m. EST)
T+plus 24 minutes, 30 seconds. About two minutes are left in the burn to reach the next orbit. Everything continues to look nominal.
0127 GMT (8:27 p.m. EST)
T+plus 23 minutes. Continued good engine operation is being delivered by the RL10C, no problems reported. Speed currently 19,527 mph.
0125 GMT (8:25 p.m. EST)
T+plus 21 minutes, 10 seconds. The engine is burning well. This is a planned six-minute firing by the Centaur's single Aerojet Rocketdyne RL10C engine.
0124 GMT (8:24 p.m. EST)
T+plus 20 minutes, 37 seconds. Ignition! The Centaur's single RL10C engine has re-ignited to climb into a highly elliptical intermediate orbit on the way to the final perch later tonight.
0124 GMT (8:24 p.m. EST)
T+plus 20 minutes, 25 seconds. Liquid hydrogen and liquid oxygen system prestarts are underway.
0124 GMT (8:24 p.m. EST)
T+plus 20 minutes. Centaur getting into its pressurization sequence.
0123 GMT (8:23 p.m. EST)
T+plus 19 minutes. The flight path is taking the vehicle over the equatorial Atlantic Ocean, soon to near the western coast of Africa where the next Centaur burn will occur. It will soar away from the Indian Ocean over the course of the next couple hours before the RL10C restarts for a final time to accelerate MUOS into the geosynchronous transfer orbit and separating the payload.
0122 GMT (8:22 p.m. EST)
T+plus 18 minutes. Centaur is half-way through this coast period. It is completing a slow roll to keep thermal heating even across the rocket's surfaces.
0121 GMT (8:21 p.m. EST)
T+plus 17 minutes, 30 seconds. That first burn by Centaur inserted the rocket into the precise target orbit as planned.
0119 GMT (8:19 p.m. EST)
T+plus 15 minutes. Centaur's onboard systems are stable in this coast period continues.
0117 GMT (8:17 p.m. EST)
T+plus 12 minutes, 35 seconds. 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 RL10C engine re-ignites for the next burn.
0117 GMT (8:17 p.m. EST)
T+plus 12 minutes, 5 seconds. Centaur is now orbital.
0116 GMT (8:16 p.m. EST)
T+plus 11 minutes, 30 seconds. About one minute are left in this burn of Centaur.
0115 GMT (8:15 p.m. EST)
T+plus 11 minutes. The RL10C continues to perform well, burning liquid hydrogen and liquid oxygen propellants.
0113 GMT (8:13 p.m. EST)
T+plus 9 minutes, 30 seconds. All systems reported stable as the Centaur fires to reach an initial Earth orbit.
0112 GMT (8:12 p.m. EST)
T+plus 8 minutes, 15 seconds. Vehicle traveling at 14,840 mph.
0111 GMT (8:11 p.m. EST)
T+plus 7 minutes, 30 seconds. The rocket has performed a planned roll to improve antenna links with NASA's orbiting Tracking and Data Relay Satellite System.
0110 GMT (8:10 p.m. EST)
T+plus 6 minutes, 30 seconds. RL10C performing well.
0109 GMT (8:09 p.m. EST)
T+plus 5 minutes. Centaur engine readings look good as this burn gets underway.
0108 GMT (8:08 p.m. EST)
T+plus 4 minutes, 55 seconds. Centaur has ignited! The RL10C engine is up and running at full thrust for its first of three firings today to reach the intended geosynchronous transfer orbit.
0108 GMT (8:08 p.m. EST)
T+plus 4 minutes, 44 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.
0108 GMT (8:08 p.m. EST)
T+plus 4 minutes, 34 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.
0107 GMT (8:07 p.m. EST)
T+plus 3 minutes, 40 seconds. The two-halves of the Atlas 5 rocket nose cone encapsulating the MUOS 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.
0107 GMT (8:07 p.m. EST)
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. The vehicle weighs just a quarter of what it did at liftoff.
0106 GMT (8:06 p.m. EST)
T+plus 2 minutes, 50 seconds. Reaction control system has been activated.
0106 GMT (8:06 p.m. EST)
T+plus 2 minutes, 40 seconds. Everything still looking good on the first stage as the rocket powers downrange on the thrust being produced by the main engine.
0106 GMT (8:06 p.m. EST)
T+plus 2 minutes, 30 seconds. Vehicle is right on course.
0105 GMT (8:05 p.m. EST)
T+plus 1 minute, 55 seconds. All five 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.
0105 GMT (8:05 p.m. EST)
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.
0105 GMT (8:05 p.m. EST)
T+plus 60 seconds into this complex three-hour mission to deploy the Navy's second Mobile User Objective System communications satellite in a geosynchronous transfer orbit.
0104 GMT (8:04 p.m. EST)
T+plus 50 seconds. A period of maximum dynamic pressure is being experienced by the rocket.
0104 GMT (8:04 p.m. EST)
T+plus 45 seconds. Mach 1.
0104 GMT (8:04 p.m. EST)
T+plus 40 seconds. The main engine is throttling down to ease the stresses on the vehicle in the lower atmosphere.
0104 GMT (8:04 p.m. EST)
T+plus 30 seconds. The vehicle is heading due eastward to reach a 28-degree inclination preliminary parking orbit 12 minutes from now.
0104 GMT (8:04 p.m. EST)
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 five solid rocket boosters burning.
0104 GMT (8:04 p.m. EST)
LIFTOFF! Liftoff of the 200th Atlas-Centaur rocket, launching the future of U.S. Navy tactical communications.
0103 GMT (8:03 p.m. EST)
T-minus 20 seconds. "Go Atlas", "Go Centaur" and "Go MUOS" was just called by launch team during a final status check.
0103 GMT (8:03 p.m. EST)
T-minus 40 seconds. Centaur's liquid oxygen and liquid hydrogen tanks are stable at flight pressures.
0103 GMT (8:03 p.m. EST)
T-minus 55 seconds. Range is green.
0103 GMT (8:03 p.m. EST)
T-minus 1 minute. Now 60 seconds away from launching the third Mobile User Objective System communications satellite to continue orbital construction of a five-spacecraft network to span the globe.
0102 GMT (8:02 p.m. EST)
T-minus 90 seconds. The rocket's safety system has been armed.
0102 GMT (8:02 p.m. EST)
T-minus 1 minute, 45 seconds. Liquid oxygen and liquid hydrogen propellant topping to the Centaur upper stage is being secured.
0102 GMT (8:02 p.m. EST)
T-minus 1 minute, 55 seconds. The launch sequencer has been commanded to start.
0102 GMT (8:02 p.m. EST)
T-minus 2 minutes. The Atlas first stage and Centaur upper stage are now switching from ground power to internal batteries.
0101 GMT (8:01 p.m. EST)
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.
0101 GMT (8:01 p.m. EST)
T-minus 3 minutes. The Atlas first stage liquid oxygen replenishment is being secured so the tank can be pressurized for launch.
0100 GMT (8:00 p.m. EST)
T-minus 3 minutes, 50 seconds. The ground pyrotechnics are enabled.
0100 GMT (8:00 p.m. EST)
T-minus 4 minutes and counting. Clocks have resumed for the final minutes of today's countdown to launch the Atlas 5 rocket with a new mobile communications satellite for the U.S. Navy from Cape Canaveral, Florida.
0059 GMT (7:59 p.m. EST)
Standing by to pick up the count.
0059 GMT (7:59 p.m. EST)
ULA and the Air Force have given their respective final approvals to resume the countdown.
0059 GMT (7:59 p.m. EST)
Range is GO!
0059 GMT (7:59 p.m. EST)
The MUOS 3 satellite has switched to internal power for launch.
0057 GMT (7:57 p.m. EST)
Polling of the team by Atlas launch conductor just occurred. The Range reports NO GO for a radio frequency issue. Everyone else polled was GO.
0056 GMT (7:56 p.m. EST)
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.
0055 GMT (7:55 p.m. EST)
The latest weather balloon shows GREEN upper level winds. However, the Range continues to work a command interference issue.
0050 GMT (7:50 p.m. EST)
NEW TIME now planned no sooner than 8:04 p.m. EST.
0048 GMT (7:48 p.m. EST)
NEW TIME now planned no sooner than 7:59 p.m. EST.
0044 GMT (7:44 p.m. EST)
NEW TIME has been targeted for 7:54 p.m. EST. But still waiting on clearance from the Range and clarity on upper level winds.
0042 GMT (7:42 p.m. EST)
HOLD extended. Tonight's launch window extends to 8:27 p.m. EST.
0039 GMT (7:39 p.m. EST)
Upper level winds are now GO. However, the Range is RED.
0035 GMT (7:35 p.m. EST)
NO GO for the Range due to a command issue.
0031 GMT (7:31 p.m. EST)
NEW LAUNCH TIME. Liftoff has slipped to 7:49 p.m. EST due to upper level winds.
0030 GMT (7:30 p.m. EST)
Here's a look at some stats about today's mission. This will be:
0024 GMT (7:24 p.m. EST)
T-minus 4 minutes and holding. The countdown has entered the planned 15-minute hold to give the launch team a chance to review all systems before pressing ahead with liftoff.
0023 GMT (7:23 p.m. EST)
T-minus 5 minutes. Standing by to go into the final built-in hold.
0018 GMT (7:18 p.m. EST)
Today marks the 52nd flight for Atlas 5, born of the Air Force's competition to develop next-generation Evolved Expendable Launch Vehicles. In its previous 51 missions since debuting in August 2002, the tally shows 18 flights dedicated to the Defense Department, 11 for NASA, 11 with spy satellites for the National Reconnaissance Office. and 11 commercial missions with communications and Earth-observing spacecraft.
0015 GMT (7:15 p.m. EST)
The final planned weather briefing to launch officials just occurred and the odds of acceptable conditions today has improved to 90 percent.
0013 GMT (7:13 p.m. EST)
Just 30 minutes until liftoff time. Today's launch is the third for the Navy's new Mobile User Objective System satellite constellation to provide mobile communications to U.S. military forces.

In its launch configuration atop the Atlas rocket with the two power-generating solar arrays stowed on the sides and the umbrella reflectors folded up, MUOS stands 22 feet tall, 12 feet wide and 6 feet deep. The craft was built on Lockheed Martin's A2100 satellite design used by dozens of previous communications spacecraft.

Following separation from the launch vehicle nearly three hours after liftoff today, ground controllers will begin maneuvering MUOS 3 into geosynchronous orbit, deploying its power-generating solar arrays to span more than 90 feet, unfurling a pair of umbrella-like antenna reflectors on boom assemblies and fully checking out the onboard communications equipment.

Eight orbital raising burns are expected over the next 8-9 days, followed by the antenna reflector deploys, then a test program that Lockheed Martin will perform. The military will take control of the satellite in a few months to conduct its own acceptance evaluation before the craft enters service early next year.

0012 GMT (7:12 p.m. EST)
The fuel-fill sequence for the first stage main engine is starting.
2358 GMT (6:58 p.m. EST)
Now 45 minutes from liftoff. Today begins a 9-launch manifest for the Atlas 5 rocket in 2015. Read our manifest story.
Earlier updates