The Delta 4 rocket debuted its latest variant with a display of power and precision Saturday night, successfully using an energetic creation to heave a vital communications satellite into space for the U.S. military.

Read our full story.

A dazzling gallery of launch photos is posted here.

A gallery of launch photos taken from the press viewing spot on the NASA Causeway are posted here.

"The WGS provides a giant leap in communications bandwidth and technology," said Secretary of the Air Force Michael Donley. "The launch of this satellite is another example of the Air Force bringing important and vital capabilities to our nation's military around the world."

"I am extremely proud to be a part of a team of space professionals that launched the third Wideband Global SATCOM satellite to complete the first phase of the WGS constellation," said Brig. Gen. Edward L. Bolton Jr., 45th Space Wing commander. "I am also pleased this marked our 20th launch of the year."

Jim Sponnick, ULA vice president of the Delta product line:

"ULA congratulates the Air Force and our mission partners on the successful launch of WGS 3. It was appropriate the Air Force, which was one of the primary customers ULA was created to support, was the customer for today's 36th launch in 36 months. WGS is also the first of the constellation of satellites to launch on both the Delta 4 and Atlas 5 since the formation of ULA. This operational flexibility was a primary reason ULA was formed and we look forward to providing this capability to our government customers for decades to come."

Here's a post-flight statement from Michael Gass, United Launch Alliance president and chief executive officer:

"I couldn't be more proud of our nearly 3,850 ULA employees and our many government partners whom I'm privileged to work with at ULA," said Gass. "This team of people, with their combined expertise, is the reason for this sustained mission success. When we formed ULA in 2006, our primary mission was to the deliver the highest reliable products for assured access to space for our government and commercial customers. Launching successfully 36 times in our first 36 months of company history is a significant accomplishment as we celebrate our third anniversary."

T+plus 40 minutes, 40 seconds. SPACECRAFT SEPARATION! The Air Force's Wideband Global SATCOM 3 military communications satellite has been deployed into orbit from the Delta 4 rocket's upper stage, completing tonight's launch.

The spacecraft will spend the next few weeks being maneuvered into geostationary orbit by controllers at Boeing's satellite facility in El Segundo, California. The orbit raising activities will use both the conventional propellant engines as well as ion propulsion thrusters.

"WGS has the chemical propulsion system, as well as xenon ion propulsion," said Mark Spiwak, the WGS program director for satellite-builder Boeing.

"When we come off the rocket, we've got a little over two weeks of the chemical burns...and 36-37 days of xenon ion propulsion that brings the inclination down and also rounds out the orbit."

Boeing will oversee the craft's solar array and antenna deployments, plus complete an initial round of testing before WGS 3 is handed over to the Air Force in February. The military plans to conduct its own set of checks and verifications, then position the craft at its orbital slot of 12 degrees West to enter service in April.

T+plus 39 minutes, 45 seconds. Separation will occur while soaring away from the planet over the Indian Ocean.

T+plus 38 minutes, 40 seconds. About two minutes from separation.

T+plus 36 minutes. The rocket is coasting in orbit and will soon deploy the next Wideband Global SATCOM, continuing the modernization effort for the U.S. military's satellite communications network in space.

T+plus 34 minutes. Release of the payload just under seven minutes away.

T+plus 32 minutes. Delta is traveling at 32,830 feet per second, some 6,209 miles downrange from the launch pad.

T+plus 31 minutes, 29 seconds. SECO 2. The second of two firings by the upper stage during today's launch has been completed, ending the powered phase of flight.

T+plus 30 minutes, 15 seconds. This burn injects the rocket into a highly elliptical orbit stretching about 36,000 nautical miles in altitude at its furthest point from Earth.

T+plus 29 minutes, 45 seconds. Engine performing well.

T+plus 29 minutes, 30 seconds. This burn will last just over three minutes in duration.

T+plus 29 minutes, 10 seconds. Pitch and yaw control are normal.

T+plus 28 minutes, 42 seconds. Good engine chamber pressure reported.

T+plus 28 minutes, 33 seconds. The RL10B-2 engine, fed by liquid hydrogen and liquid oxygen, has been ignited once again! This firing will propel WGS 3 to its targeted orbit.

T+plus 25 minutes, 30 seconds. The vehicle is now in a coast mode before the next firing of the upper stage engine. Re-ignition of the RL10 engine is three minutes away.

T+plus 24 minutes. To see the track the rocket is following this evening, click here.

T+plus 23 minutes. The upper stage is reorienting to the proper position for the next burn.

T+plus 22 minutes. The initial orbit appears to be right on target.

T+plus 20 minutes, 31 seconds. SECO 1. Confirmation that the second stage engine has shut down after the first of two planned firings to inject the WGS 3 spacecraft into a supersynchronous transfer orbit.

T+plus 19 minutes, 20 seconds. Delta is traveling at 27,503 feet per second over the central Atlantic Ocean.

T+plus 18 minutes. The upper stage's the RL10 engine working well, still firing as planned to reach the parking orbit this evening.

T+plus 17 minutes, 5 seconds. Delta is traveling at 24,897 feet per second, 2,361 miles downrange from the launch pad.

T+plus 16 minutes, 30 seconds. About four minutes remain in this firing of the second stage.

T+plus 15 minutes, 40 seconds. The telemtry relay duties for the rest of the mission are being handed from ground stations to NASA's Tracking and Data Relay Satellite System.

T+plus 14 minutes, 30 seconds. This burn will place the vehicle into an initial parking orbit around Earth. The rocket is headed for an elliptical orbit of 100 by 3,714 nautical miles with an inclination of 25.59 degrees.

T+plus 13 minutes, 30 seconds. The RL10 engine is burning a mixture of liquid oxygen and liquid hydrogen cryogenic propellants. Chamber pressures still look good.

T+plus 12 minutes, 30 seconds. Normal chamber pressures and good pitch and yaw steering reported.

T+plus 12 minutes, 15 seconds. Delta is 221 miles in altitude, 1,418 miles east of the launch pad.

T+plus 11 minutes, 30 seconds. The vehicle's steep climb leveled off as it gains speed toward orbital velocity. Delta is 227 nautical miles in altitude, 1,228 miles downrange from the launch pad.

T+plus 10 minutes, 20 seconds. The upper stage is stable and giving WGS 3 a good ride.

T+plus 9 minutes, 10 seconds. Delta is 222 miles in altitude, 919 miles east of the launch pad.

T+plus 8 minutes, 30 seconds. The second stage engine continues to fire. All is looking good.

T+plus 7 minutes, 30 seconds. The upper stage is the larger five-meter version that has flown three previous times on the Delta 4-Heavy vehicle, another element that distinguishes this Medium+ (5,4) rocket configuration. The earlier Medium variants used four-meter upper stages.

Today's stage has a wider liquid hydrogen tank and a lengthened liquid oxygen tank to carry additional propellants, enabling the RL10 engine to fire longer.

T+plus 6 minutes, 50 seconds. Good controls by the upper stage. Delta is 186 miles in altitude, 587 miles downrange from the launch pad.

T+plus 6 minutes, 10 seconds. Delta is 167 miles in altitude, 484 miles east of the launch pad.

T+plus 5 minutes, 50 seconds. Good chamber pressure data being reported from the RL10 engine as it thrusts to reach orbit.

T+plus 5 minutes, 30 seconds. Delta is 148 miles in altitude, 402 miles east of the launch pad.

T+plus 4 minutes, 55 seconds. Delta is 128 miles in altitude, 321 miles east of the launch pad.

T+plus 4 minutes, 26 seconds. The cryogenic RL10B-2 upper stage engine has been lit!

T+plus 4 minutes, 14 seconds. The Common Booster Core first stage and the attached interstage have been separated in one piece. The upper stage engine's extendible nozzle is dropping into position to prepare for ignition.

T+plus 4 minutes, 5 seconds. MECO! Main engine cutoff confirmed as the RS-68 powerplant shuts down.

T+plus 3 minutes, 57 seconds. The main engine is throttling down to 57 percent thrust for the rest of its firing in today's launch.

T+plus 3 minutes, 26 seconds. The protective payload fairing enclosing the WGS 3 satellite atop the rocket has separated.

T+plus 2 minutes, 55 seconds. Altitude 51 nautical miles, 84 nautical miles downrange.

T+plus 2 minutes, 40 seconds. The main engine continues to burn, consuming its liquid hydrogen and liquid oxygen propellants.

T+plus 2 minutes, 10 seconds. Altitude 31.4 miles, 38.2 miles downrange.

T+plus 2 minutes. The RS-68 is consuming nearly a ton of propellants per second as the powerplant pushes the Delta 4 rocket closer to space.

T+plus 1 minute, 44 seconds. Solid motor separation! The spent boosters have been shed from the first stage. Delta 4 continues powering its way on the thrust generated by the RS-68 main engine.

T+plus 1 minute, 34 seconds. The four solid rocket boosters have burned out of their propellant. Standing by for jettison.

T+plus 50 seconds. Now passing through the region of maximum aerodynamic pressure.

T+plus 36 seconds. The launcher has broken through the sound barrier.

T+plus 20 seconds. The Delta 4 rocket cleared the Complex 37 towers in a heartbeat and continues racing away from the spaceport with its main engine firing at full throttle and the four strap-on motors giving an impressive boost in speed.

LIFTOFF! Liftoff of the energetic new version of Delta 4 launching a sophisticated communications relay satellite for U.S. military forces overseas.

T-minus 12 seconds. Residual hydrogen burnoff ignitors have been fired beneath the main engine.

T-minus 22 seconds. The steering system for the solid rocket motor nozzles has been activated.

T-minus 30 seconds. Green board. All systems remain "go" for launch.

T-minus 40 seconds. Upper stage liquid hydrogen tank is confirmed at flight level.

T-minus 1 minute and counting. The ignition conditions for the RS-68 main engine are "go." The terminal countdown sequencer will take control at T-minus 8.5 seconds. Ignition of the RS-68 powerplant will follow at T-minus 5.5 seconds. The engine powers up to the 102 percent level of thrust for a computer-controlled checkout before liftoff.

T-minus 70 seconds. The Air Force-controlled Eastern Range has given its "go" for launch.

T-minus 75 seconds. The liquid hydrogen fuel tank on the upper stage is being secured for launch.

T-minus 80 seconds. Upper stage liquid oxygen tank has been secured at flight level.

T-minus 1 minute, 50 seconds. The first stage liquid hydrogen tank has reached flight level and pressure.

T-minus 2 minutes. The rocket's upper stage liquid oxygen tank is being secured.

T-minus 2 minutes, 45 seconds. The liquid oxygen tank in the first stage is confirmed at the proper level and pressure for flight.

T-minus 3 minutes, 15 seconds. Replenishment of liquid hydrogen and liquid oxygen to the Common Booster Core first stage is being secured in preparation to pressurize the tanks for launch.

T-minus 4 minutes and counting. Ordnance devices aboard the vehicle are being armed.

T-minus 4 minutes, 10 seconds. The systems of the first and second stages of the Delta 4 rocket have switched from ground-fed power to internal batteries for launch.

T-minus 5 minutes and counting! The final phase of today's countdown has commenced for launch of the Delta 4 rocket carrying the Wideband Global SATCOM spacecraft. Liftoff is set to occur at 8:47 p.m. EST (0147 GMT) from pad 37B at Cape Canaveral Air Force Station.

The launch director has given approval given to resume the count for liftoff at 8:47 p.m. EST. The winds aloft declared "go" for launch!

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

• The 346th Delta rocket launch since 1960
• The 11th Delta 4 rocket mission since 2002
• The 9th Delta 4 rocket launch from Cape Canaveral
• The 8th Delta 4 flight for the Air Force
• The first Medium+ 5,4 configuration to fly
• The 10th launch of the Delta family in 2009
• The third Delta 4 of 2009
• The 36th United Launch Alliance mission in 36 months
• The fourth Delta 4 under the ULA banner

The launch pad swing arm retraction system pins are being pulled. The three arms will be rotated away from the Delta 4 rocket at liftoff.

The launch conductor just performed another readiness poll of his team. All elements remain "ready" for flight.

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The launch team will be re-polled at 8:37 p.m. to verify systems remain ready for liftoff once the winds are declared acceptable. There won't be any additional margin to delay liftoff tonight. The window closes at 8:47 p.m. EST.

NEW LAUNCH TIME. Liftoff is being targeted for the very end of today's launch window at 8:47 p.m. EST. That's because there was a problem transmitting the latest weather balloon data to engineers at the United Launch Alliance facilities in Denver. The time to re-send the info will push back when the flight data will be ready.

NEW LAUNCH TIME. Liftoff has delayed to 8:37 p.m. EST. There was a problem with one of the weather balloons that has added some time before the next data will be available.

To recap, the countdown is holding at the T-minus 5 minute mark while engineers assess the wind conditions in the atmosphere that the Delta 4 rocket will fly through tonight. Concerns about those upper level winds have delayed liftoff twice so far, scrapping target launch times of 7:23 and 8:00 p.m. EST.

The team is expecting the next flight data file based upon the newer weather balloon information to be ready for transmission to the rocket around 8:15 p.m. EST.

If the conditions aloft are deemed improved and acceptable, the launch will occur at 8:30 p.m. EST.

The last moment that launch could happen tonight is 8:47 p.m. EST. That is when the window closes for today.

NEW LAUNCH TIME. Liftoff has been retargeted for 8:30 p.m. EST.

DELAY. The launch will be pushed back from the 8:00 p.m. EST target. The latest balloon has shown "no go" conditions in comparison to the previous data run.

The final readiness polls have been completed and all team members voiced "ready" status for continuing the countdown except for one. Officials are waiting on confirmation of acceptable upper level winds based on the next balloon.

The launch team is being polled to confirm all systems are "go" to press onward for 8:00 p.m. EST launch.

The revised data file is being loaded into the Delta 4 rocket's guidance computer based on the latest upper level wind information.

The team is complete with all of its procedures up to the Launch Minus 10-minute point. Pending a "go" on upper level winds, countdown activities would restart at 7:50 p.m. in preparation for a liftoff at 8:00 p.m. EST.

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NEW LAUNCH TIME. Liftoff has been retargeted for 8:00 p.m. EST. That will allow the team to receive and process new weather balloon data on the winds aloft.

A new target liftoff time has not yet been established. The countdown remains holding at T-minus 5 minutes. Tonight's launch window extends from 7:23 to 8:47 p.m. EST.

Our live stream of tonight's launch is working again! Apologies for the early difficulties. Just hit reload on this page and the video will automatically start.

DELAY. Liftoff will not occur at 7:23 p.m. because upper level wind conditions have been declared "no go" again.

The launch team will be polled in the next minute to confirm all systems are "go" to press onward for 7:23 p.m. EST liftoff.

The WGS 3 spacecraft atop the Delta 4 is switching from ground-fed power to its internal batteries for launch.

Our live video stream of the launch is back after a technical glitch. Just hit reload to this page.

T-minus 5 minutes and holding. The countdown has entered the planned 15-minute hold leading toward the 7:23 p.m. EST liftoff of the Delta 4 rocket.

This pause is designed to give the launch team the opportunity to catch up on any work running behind schedule and verify all is in readiness for the final moments of the count. A series of management polls will be conducted during the hold to give approval to proceed with the launch.

The final guidance update on upper level winds is being loaded into the rocket. At the current time, the winds are acceptable.

For those looking to watch the ULA broadcast of the launch, here's a link.

The external inspections of the Delta 4 rocket's thermal insulation following fueling has been completed without any issues of note.

Current observations show no violation of the cloud rules, there's no rain in the area and ground winds are within limits. The upper level winds are the only issue being watched.

T-minus 30 minutes and counting. The countdown is headed to the T-minus 5 minute point where a 15-minute hold is planned. Liftoff is targeted for 7:23 p.m., the opening of today's 84-minute launch window.

The engine slew checks have been performed successfully. The test sequence started with the upper stage RL10 engine, followed by the first stage RS-68 engine gimbaling and then some commanding checks for the strap-on solid rocket motors.

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No technical issues are being reported in the countdown and the team remains on the timeline for launch at 7:23 p.m. EST.

The propellant conditioning has been completed on all four cryogenic tanks. The Delta 4 rocket is fueled up and ready for today's launch window to open.

Now moving into the final 60 minutes of the countdown.

This launch will deliver to orbit the third satellite in the Wideband Global SATCOM series. Although more spacecraft are under construction in the Block 2 phase of the program, today's deployment of WGS 3 marks the last satellite in Block 1.

"The upcoming launch of WGS is really a landmark achievement for the DOD and The Boeing Company. It completes the initial constellation of three WGS satellites that will provide vital, flexible, high-capacity communications to the U.S. warfighters and allies across the theaters of operation," said Mark Spiwak, the WGS program director at Boeing.

Boeing shipped the WGS 3 satellite from its factory in El Segundo to Cape Canaveral on September 28. Over the past two months, the craft underwent final testing, fueling and encapsulation in the shroud that will cover it during launch.

On November 14, the spacecraft was transported from the Astrotech processing facility in Titusville to Complex 37 where it was hoisted atop the Delta 4 rocket.

"It's ready to join its brothers in arms -- WGS 1 and 2 -- in providing this capability to the men and woman of our armed forces. We look forward to a great ride from ULA," said Spiwak.

The company has three additional WGS satellites currently in production for launches slated to start in 2011.

"On behalf of The Boeing Company, we are very proud to be providing them to the United States Air Force. They are a key element in the very highly flexible and capable system providing this quantum leap in communications for the warfighter."

The engine steering tests are getting underway.

The RS-68 first stage main engine spin start pressurization operation is about to start.

The streaming video on the right-hand side of this page is having technical difficulties. But while we work on that, our iPhone feed can be watched on your computer if you have the latest version of QuickTime installed. Check it out!

The safety system checks are being performed at this point in the countdown.

The launch team is entering the last 90 minutes of the countdown. With fueling of the Delta 4 rocket completed, team members are monitoring systems while the clocks tick down.

In the immediate future, the rocket's safety system will be checked and a series of engine steering tests will occur.

Everything continues to proceed on schedule at Cape Canaveral for liftoff at 7:23 p.m. EST. The upper level winds are the main thing being watched right now.

Engineers are conducting the standard evaluation of the Delta 4 rocket's thermal insulation following the loading of supercold propellants into the vehicle.

Launch of the Delta 4 rocket with the third Wideband Global SATCOM spacecraft is just two hours away.

The first two WGS satellites were hauled into space aboard Atlas 5 rockets. But WGS 3 is riding atop the Delta 4, the other rocket in the Air Force's Evolved Expendable Launch Vehicle fleet. Both vehicles are produced by United Launch Alliance, the firm created three years ago this month that joined Lockheed Martin's Atlas and Boeing's Delta rockets under one organization.

"This mission is symbolic of why ULA formed for a couple of reasons," says James Bell, ULA's WGS mission manager.

"First, it exemplifies why the government brought the Atlas and Delta programs together. The first two WGS satellites were launched on our Atlas vehicles and for WGS 3, instead of our Delta 4 team having to start from scratch, ULA was proactive in implementing a seamless integration and processing services for this repeat customer.

"Also, because I was the WGS mission manger for those two Atlas launches, I was able to share the knowledge we gained from those launches with our Delta team. This is not only a tremendous benefit for ULA but also for our Air Force mission partners who are relying on us to provide them assured access to space. This simply wasn't possible prior to ULA.

"Second, this mission marks the 36th launch for ULA in 36 months, which is quite a record of reliability and mission success. When ULA was formed, our primary goal was to provide safe and reliable assured access to space with mission success paramount in everything we do."

The upper stage liquid oxygen tank has been filled up, now making the Delta 4 a fully fueled rocket.

For the first time in a couple of days at the Cape, the clouds are giving way to the sun. This low overcast is sliding out!

The first stage liquid hydrogen tank is being placed into its topping phase.

Now entering the last two-and-a-half hours of the countdown. Fueling of the Delta 4 rocket continues in work for the 7:23 p.m. EST launch of the WGS 3 military communications satellite from Cape Canaveral, Florida.

A status check of the fueling activities shows the fast-fill loading to the upper stage liquid hydrogen tank just ended. The launch team continues to load the liquid oxygen supply to the stage.

The upper stage conditioning on the liquid oxygen side has finished. Loading of the tank is starting. This is the last of the rocket's four cryogenic supplies to be filled in today's countdown to launch.

Post-filling tests on the first stage liquid oxygen system are complete and the tank is going into topping mode.

The official launch weather forecast has removed the concern for thick clouds for tonight. A line of clearing is making its way toward the Cape, there's no rain in the area and the surface winds remain below limits.

The upper wind conditions are being closely watched, however, due to a strong wind shear up through 15,000 feet. A pre-planned series of weather balloons will be released throughout the countdown to monitor the direction and speed of the winds for engineers to select the best flight profile for launch.

After finishing up work on the first stage liquid oxygen side, the launch team is moving into the chilldown procedures for the upper stage liquid oxygen system.

Fast-fill just finished for the first stage liquid hydrogen tank.

Live streaming video of the Delta 4 rocket can be viewed on your iPhone. Check it out!

The chilldown of the upper stage stage liquid hydrogen system is reported complete, clearing the way for loading the rocket's tank.

The "go" has been given for the upper stage liquid oxygen chilldown in advance of fueling.

The loading of liquid oxygen into the Common Booster Core first stage has been completed. The launch team will conduct vent and valve checks before putting the tank into topping mode.

Complex 37 has two giant sphere-shaped fuel tanks to store the cryogenic liquid oxygen and liquid hydrogen. The LOX tank holds 250,000 gallons and LH2 sphere about 850,000 gallons. Complex 37 has two giant sphere-shaped fuel tanks to store the cryogenic liquid oxygen and liquid hydrogen. The LOX tank holds 250,000 gallons and LH2 sphere about 850,000 gallons.

The cryogenics are fed from the storage tanks through pipelines to the pad. For the Common Booster Core, the propellants are routed up to the launch table upon which the rocket sits. Tail service masts, the large box-like structures at the base of the vehicle, feed the oxygen and hydrogen to the booster via separate umbilicals.

The upper stage will be filled in a little while. It receives the cryos from the middle swing arm that extends from the Fixed Umbilical Tower to the front-side of the rocket.

The launch team has gotten the approval to start chilldown conditioning of the upper stage liquid hydrogen system.

First stage liquid oxygen loading continues in progress. The rocket's tank will be loaded with 40,000 gallons of the supercold oxidizer that's chilled to Minus-298 degrees F.

The countdown sequence is on schedule and no problems are being worked, the launch team reports.

First stage liquid hydrogen tanking operation is switching from "slow-fill" to "fast-fill" mode. Some 110,000 gallons of LH2 will load up the rocket's tank.

The first stage liquid oxygen and liquid hydrogen loading in "slow-fill" mode has commenced.

The cold gas chilldown conditioning of the liquid hydrogen system has been accomplished. Liquid hydrogen propellant will start to flow into the first stage in "slow-fill" mode. That is sped up to "fast-fill" after a small portion of the tank is loaded.

Chilled to Minus-423 degrees Fahrenheit, the liquid hydrogen will be consumed by the RS-68 main engine along with liquid oxygen during the first four minutes of the launch.

The first stage liquid oxygen chilldown is complete. Fueling is beginning in the "slow-fill" mode to load a small percentage of the tank. The process then speeds up to the "fast-fill" mode until the tank is nearly full.

A little less than five hours until liftoff time. No significant technical issues are being tracked and the launch team is active with the thermal conditioning of the first stage for fueling.

A "go" has been given to start the cold gas chilldown conditioning of the first stage liquid hydrogen system.

Chilldown of the first stage liquid oxygen system is beginning. This preps the tank and pumping to guard against shock when the supercold oxidizer begins flowing into the rocket a short time from now.

The launch director has given approval for the start of fueling operations.

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T-minus 5 hours, 15 minutes and counting! The Terminal Countdown has commenced for this evening's scheduled launch of the Delta 4 rocket to deliver a new communications satellite into orbit for the United States military.

The countdown has one planned built-in hold at T-minus 5 minutes lasting some 15 minutes, leading to liftoff at 7:23 p.m. EST (0023 GMT).

The launch pad has been verified evacuated of all personnel in advance of fueling the rocket's two stages this afternoon. Pad systems and equipment stand ready for fueling activities, which should kick off shortly.

Checks of the C-band beacon are beginning. This system is used in tracking the rocket during the flight downrange.

The launch team has been polled to verify all consoles are manned and ready to begin the Terminal Countdown when this hold ends at 1:53 p.m. A briefing on countdown procedures is now underway.

The weather officer says the thick clouds and rain have moved to the south and east of Complex 37, giving more optimism about the chances for a launch today.

It remains a gloomy overcast sky at the Cape. But meteorologists report the low clouds are thin and not violating any of the weather criteria. At the present time, the weather is "go" for launch.

The main worry for this evening will be the winds. Overall, the odds of acceptable weather during the 7:23 to 8:47 p.m. EST launch window have improved to 60 percent.

The revised launch forecast calls for some broken decks of clouds at 4,000 and 8,000 feet, good visibility, northwesterly winds of 15 peaking to 20 knots and a temperature around 56 degrees F.

The outlook for Sunday night, if the launch should slip 24 hours for some reason, is 80 percent favorable with lighter winds and scattered clouds.

The call to "man stations for Terminal Count" just went out to the launch team.

T-minus 5 hours, 15 minutes and holding. The countdown has just entered a planned 60-minute built-in hold, giving the team time to catch up on any work that could be running behind schedule. Once the clocks resume ticking at 1:53 p.m. EST, the Terminal Countdown phase of today's launch operation will begin.

Here's some fresh photos taken this morning at pad 37B as the second launch attempt began. See the gallery.

The cold front passed over the launch site a short time ago, producing some wind gusts around 29 knots as a light, constant rain continues to fall over the Space Coast.

But the launch weather officer says with the front now moving on southward, the winds should settle down this afternoon to the 20-22 knot range and the rain will end.

For the rest of the countdown and this evening's launch window, the concerns will be the thickness of the clouds overhead and surface winds hovering around the liftoff constraint of 20 knots.

Meteorologists are hopeful that the clouds will thin and scatter out this afternoon and they'll be keeping a close eye on the wind speeds at the pad.

The second launch attempt is officially underway at Cape Canaveral today for the Delta 4 rocket that will place the third Wideband Global SATCOM military satellite into Earth orbit.

Ground technicians have rolled the 330-foot tall mobile service tower away from the rocket, retracting the wheeled structure along rail tracks to its launch position about the length of a football field away from the Delta 4. The 9-million pound tower shielded the rocket from the elements during the stay on the pad, provided workers 360-degree access to the various areas on the vehicle and was used to attach the strap-on solid motors and the payload during the launch campaign. The tower is 90-feet wide and 40-feet deep.

Crews will spend the next couple of hours securing the complex for launch before leaving the danger area around the pad. All workers must be clear of the area for the start of hazardous operations in the countdown, which include fueling the vehicle later this afternoon.

Liftoff remains scheduled for 7:23 p.m. EST.

After resolving a minor technical glitch and waiting out rainy weather, the Delta 4 rocket is targeting a Saturday evening blastoff from Cape Canaveral to deploy a sophisticated communications satellite for the U.S. military.

Liftoff from Complex 37 will be possible during an 84-minute window extending from 7:23 to 8:47 p.m. EST (0023-0147 GMT).

Air Force officials said late Friday that the faulty electronics card has been replaced in a piece of ground support equipment used to monitor telemetry data. The issue arose during Thursday's countdown, ultimately leading to the launch postponement.

A gloomy weather forecast caused Wednesday's original launch opportunity to be scrapped in advance and unfavorable conditions were a problem during Thursday's countdown as well. Persistent rain fell all day on Friday and meteorologists are giving only 40 percent odds of acceptable weather during Saturday night's try.

Once the rocket does fly, it will perform a 40-minute ascent to supersynchronous transfer orbit to launch the Air Force's third Wideband Global SATCOM communications spacecraft, known as WGS 3.

WGS satellites are giving a major upgrade to the military's main communications infrastructure, replacing the aging Defense Satellite Communications System spacecraft. Each WGS has 10 times the capacity of a DSCS satellite, allowing users to process and receive data quicker than ever before.

The new WGS 3 satellite will be positioned above the Eastern Atlantic at an orbital slot of 12 degrees West longitude to serve the U.S. European Command and U.S. Africa Command, plus lend additional support over the Middle East.

WGS 1 entered service last year to cover the vast Pacific Command that spans the U.S. western coast all the way to Southeast Asia. The WGS 2 satellite launched earlier this year was placed into operation over the Indian Ocean for use by U.S. Central Command to provide coverage for the warfighters in Afghanistan, Iraq and other parts of Southwest Asia.

The launch weather officer is predicting a 40 percent chance of acceptable conditions on Saturday and an 80 percent favorable outlook for Sunday evening.

Here is this morning's official Air Force statement to the press:

"The launch of the Air Force's Delta 4 Wideband Global SATCOM 3 (WGS 3) mission is now targeted for December 5 with a launch window of 7:23-8:47 p.m. EST.

"After evaluating the situation, mission managers believe this will give the launch team the time required to replace an electronics card that is part of the ground equipment used to monitor telemetry data from the Delta 4 and related systems for the launch. An anomaly with this monitoring system hardware led to the scrub of the first launch attempt December 3.

"The Delta 4 and WGS 3 spacecraft are safe and secure.

"Further updates on the status of the Delta 4 WGS 3 mission will be issued as new information is available."

DELAY. Officials have decided to forego making another launch attempt today. Liftoff has been pushed back to Saturday evening at the earliest.

Here's the official Air Force statement to the press:

"The launch of the Air Force's Delta 4 Wideband Global SATCOM 3 (WGS 3) mission was scrubbed this evening due to additional time required to troubleshoot an anomaly with a ground launch control system. A second launch attempt has been preliminarily rescheduled for Friday, December 4, with a launch window of 7:22-8:45 p.m. EST."

SCRUB. This evening's attempt to launch the Delta 4 rocket and the third Wideband Global SATCOM military communications satellite has been postponed after a long hold caused by upper level winds, thick clouds, rain and some sort of technical issue.

Another countdown is possible on Friday, leading to liftoff at essentially the same time. However, weather forecasters are predicting extensive cloud cover, rain and thunderstorms in the area, gusty winds and only a 30 percent chance of conditions being within limits.

Read our earlier status center coverage.