An Atlas 5 rocket escaped the heavy blanket of fog smothering its launch pad this morning and successfully powered to space to deploy a new global weather observatory for America's military.

Read our full launch story.

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Some post-launch comments from the Atlas and Centaur engine folks:

"Pratt & Whitney Rocketdyne congratulates United Launch Alliance on the historical milestone of 600 Atlas launches, and we are proud to have been part of the program since the first launch from Cape Canaveral Air Force Station, Fla., in 1957," said Jim Maus, director, expendable propulsion programs, Pratt & Whitney Rocketdyne.

"The AV-017 launch represents the 24th consecutive successful mission for the RD-180 engine powering an Atlas launch vehicle," said Len Dest, president and CEO of RD AMROSS.

"An outstanding team effort all around. Spacelift operations are an immense technical undertaking and, once again, Vandenberg has delivered," said Col. Steven Winters, 30th Space Wing vice commander at Vandenberg Air Force Base.

"This mission is absolutely critical to the warfighter," said Winters. "Thanks to the hard work and dedication of this team, our fellow servicemembers and allies around the world can carry out their missions with the best weather data available."

This launch of the DMSP satellite has the distinction of being the 600th Atlas flight dating back to 1957.

"This is a proud moment in the 52 year history of the Atlas program and for United Launch Alliance," said Mark Wilkins, ULA vice president for Atlas. "First, I want to thank our Air Force customer for trusting ULA to launch this important mission. I'd also like to recognize all the men and women who have served on the Atlas team since 1957. Their determination, dedication and attention to detail have made this significant milestone possible. Combining our Atlas and Delta launch vehicle program's more than 100 years of experience gives ULA the most experienced space launch team in the world."

With the primary objective of today's launch now complete, the Centaur upper stage will spend the next couple of hours performing experiments with the excess fuel left over from the ascent.

Air Force and United Launch Alliance officials previewed the tests in a pre-flight briefing:

"We have a unique opportunity with the Atlas 5/DMSP launch, as DMSP is a relatively lighter spacecraft than many of those that fly on Atlas. For that reason, we have a tremendous amount of performance margin. That's certainly not the case for some future missions that Atlas will be flying. So we're taking advantage of the opportunity before us to use some of that excess performance margin on the Atlas 5," said Col. Michael Moran, the Atlas Group commander.

"After we have a fully separated spacecraft in its intended orbit and maneuvered the Centaur away to allow safe passage of the spacecraft, we're going to begin a series of tests to fully categorize the Centaur's performance, and based on that lesson, be able to further Atlas' capability for future missions that would go directly into geosychronous orbit, as well as refine our performance margins."

Mark Wilkins, ULA's vice president of the Atlas program, then offered these specifics about what engineers hope to learn:

"Basically, the experiments fall into two categories. One is zero-g, long-coast propellant management techniques and verification of how effective they are, as well as some performance improvements. I do want to point out that these experiments take place well after the primary mission. This is a short mission. It is about 18 minutes long, so then we do about a standard 17-minute collision avoidance. So we're over a nautical mile away away from the primary payload when we start these experiments.

"We are looking at an experiment where we do a zero-g settling by very reduced modulation of our settling thrusters. That's to preserve hydrazine. Then we also go into an experiment where we settle the propellants against the wall of the tank by spinning the stage with no settling thrusters. That's also to manage our propellants and minimize our hydrazine margin. We do some venting during the zero-g to verify that we can vent our tanks with our propellant management techniques at zero-g's.

"Then moving into some performance enhancements, we are looking at a pulsed chilldown demo for the final start of the RL10, then some experiments related to the depletion of the RL10. We're actually using a modified minimum residual shutdown algorithm to increase our performance. And also we're going vent the LOX tank during the final burn as well, and that would give us more mission flexibility."

The experiment phase culminates with the Centaur's RL10 engine igniting nearly three hours into the flight for a burn lasting about three minutes and 40 seconds, sending the rocket into an Earth-escape trajectory.

"One question that does come up is the disposal orbit for this mission is a heliocentric or Sun-centric orbit. The question would come up of why did we chose that orbit vs. a deorbit burn into the Pacific Ocean? One of the reasons for that was that we wanted to do a controlled depletion burn, we wanted to see the burn all the way through until the minimum residual shutdown. So we chose to do an escape burn vs. a deorbit burn. The experiment that we run in that burn we actually put them into place after we have achieved escape velocity for the Centaur," Wilkins said.

T+plus 18 minutes, 10 seconds. SPACECRAFT SEPARATION! The Defense Meteorological Satellite Program F18 spacecraft has been released from the United Launch Alliance Atlas 5 rocket, completing today's ascent from Vandenberg Air Force Base in California.

The Lockheed Martin-built craft carries a sophisticated suite of weather instruments to observe virtually the entire planet twice daily. Data from DMSP satellites is used to create global weather forecasts that military commanders and strategic planners rely upon.

The satellites can track weather systems by visible and infrared cloud-cover imagery, day or night, plus monitor ice and snow coverage, pollution and fires.

The new DMSP F18 is slated to replace an aging satellite launched six years ago today.

T+plus 16 minutes, 20 seconds. Confirmation has been received that the Centaur main engine cutoff occurred following its burn to inject the DMSP F18 spacecraft into polar orbit.

T+plus 16 minutes. The burn should be complete. Awaiting acquisition of data from the rocket to verify that.

T+plus 10 minutes, 30 seconds. About five minutes remain in this burn of Centaur's single Pratt & Whitney Rocketdyne RL10 engine.

T+plus 8 minutes. The RL10 is burning liquid hydrogen and liquid oxygen propellants.

T+plus 6 minutes. Centaur engine readings look normal as this 11-minute burn continues.

T+plus 4 minutes, 40 seconds. The two-halves of the Atlas 5 rocket nose cone encapsulating the spacecraft have separated.

T+plus 4 minutes, 27 seconds. Centaur has ignited! The RL10 engine is up and running at full thrust.

T+plus 4 minutes, 20 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, 10 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, 55 seconds. The RD-180 main engine continues to fire normally, burning a mixture of highly refined kerosene and liquid oxygen.

T+plus 3 minutes, 30 seconds. The rocket is 50 miles in altitude, some 69 miles downrange and traveling at 6,400 mph.

T+plus 3 minutes, 20 seconds. The engine has throttled down to 92 percent as planned.

T+plus 3 minutes. RD-180 is performing well as the rocket climbs away from the planet.

T+plus 2 minutes, 25 seconds. The rocket now weighs half of what it did at liftoff.

T+plus 2 minutes. Atlas is flying due south from Vandenberg and looking good.

T+plus 85 seconds. Mach 1 as the main engine fires at full throttle.

T+plus 60 seconds. One minute into the ascent. It will take 18 minutes for the two-stage rocket to deploy the satellite into the planned orbit.

T+plus 30 seconds. The Atlas 5 rocket is thundering toward orbit with the U.S. military's DMSP F18 weather satellite that will replace the six-year-old DMSP F16. At this moment, that spacecraft is flying 461 nautical miles over the Middle East in its pole-to-pole orbit.

T+plus 15 seconds. And the vehicle has cleared the tower at foggy Space Launch Complex 3.

LIFTOFF! Liftoff of the Atlas 5 rocket and the new global weather observatory for America's men and women in uniform.

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 from launch of the 600th Atlas.

T-minus 90 seconds. The safety system has been armed.

T-minus 1 minute, 50 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 the DMSP F18 weather satellite for the U.S. Air Force. Liftoff is set to occur at 9:12 a.m. local.

Countdown clocks will resume in one minute.

The ULA launch director and the government mission director each have given their approval to press onward with the countdown.

Polling of the team by Atlas launch conductor just occurred. All systems are reported "go" to continue with the countdown for liftoff at 5:35 p.m.

The launch team is being polled for a "go" or "no go" to proceed with the count.

Now 10 minutes away from the scheduled launch time. The final readiness polls will be performed shortly.

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

• The 600th launch for Atlas program since 1957
• The 286th Atlas to occur from Vandenberg AFB since 1959
• The 35th Atlas to use Space Launch Complex 3
• The 18th launch of an Atlas 5 since 2002
• The second Atlas 5 to occur from Vandenberg
• The 10th Atlas 5 under United Launch Alliance
• The 9th Atlas 5 to fly in the 401 configuration
• The 7th Department of Defense launch of Atlas 5

T-minus 4 minutes and holding. The countdown has entered the planned 20-minute hold to give the launch team a chance to review all systems before pressing ahead with liftoff. Today's launch opportunity stretches from 9:12 to 9:22 a.m. PDT.

All three cryogenic tanks are reported at flight level.

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

Thirty minutes from liftoff now. The countdown clocks are heading to the T-minus 4 minute mark where a planned 20-minute hold will occur. Launch of Atlas 5 remains scheduled for 9:12 a.m. PDT.

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

Today's mission for the Atlas 5 rocket is the delivery into orbit of Defense Meteorological Satellite Program F18, a new weather satellite built by Lockheed Martin for the U.S. military.

"After several years of building, integrating, upgrading and testing DMSP Flight 18, the third of the Block 5D-3 spacecraft, we at Lockheed Martin are eagerly anticipating this launch so this satellite can carry out its vital mission of supporting our warfighters," said Paul Angola, director of West Coast Operations for Sensing and Exploration Systems.

"Lockheed Martin's partnership with the Air Force dates to the very beginning of the DMSP program with a common goal of ensuring that commanders have access to environmental data critical to the preparation and execution of military operations."

The DMSP Block 5D-3 series of satellites accommodates larger sensor payloads than earlier generations, a better power subsystem, an increased battery capacity and a more powerful onboard computer with increased memory. This will be the second DMSP satellite with an enhanced attitude control subsystem featuring inertial measurement units with ring laser gyroscopes instead of mechanical ones.

The Centaur liquid oyxgen and the Centaur liquid hydrogen tanks are confirmed at flight level.

Now 60 minutes from liftoff. All activities are proceeding toward a liftoff at 9:12 a.m. Pacific Time.

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

The Centaur liquid hydrogen tank is 70 percent loaded so far. The cryogenic propellant will be consumed with liquid oxygen by the stage's Pratt & Whitney-made RL10 engine.

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

Passing the 90 percent mark in the first stage liquid oxygen tank and the 30 percent level in the Centaur's liquid hydrogen tank.

Chilldown of the liquid hydrogen system is now complete, allowing the super-cold rocket fuel to begin filling the Centaur upper stage.

Centaur's liquid oxygen is reported at flight level.

The first stage liquid oxygen tank is 50 percent full.

Now 90 minutes from the scheduled launch time. The Centaur engine chilldown sequence is being initiated.

First stage liquid oxygen tank is passing the 30 percent mark. Chilled to Minus-298 degrees F, the liquid oxygen will be used with RP-1 kerosene by the RD-180 main engine on the first stage during the initial four minutes of flight today. The 25,000 gallons of RP-1 were loaded into the rocket earlier.

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

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

The chilldown conditioning of liquid hydrogen propellant lines is starting to prepare the plumbing for transferring the Minus-423 degree F fuel into the rocket. The Centaur holds about 13,000 gallons of the cryogenic propellant.

The Centaur liquid oxygen tank is three-quarters full now.

Half of the Centaur liquid oxygen tank has been filled already.

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

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 about 50,000 gallons of cryogenic oxidizer for the RD-180 main engine.

Filling of the Centaur upper stage with about 4,300 gallons of liquid oxygen has begun at Vandenberg's Space Launch Complex 3 following the thermal conditioning of the transfer pipes.

The liquid oxygen -- chilled to Minus-298 degrees F -- will be consumed during the launch by the Centaur's single RL10 engine along with liquid hydrogen to be pumped into the stage a little later in the countdown.

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 for this morning's flight of the Atlas 5 rocket following the planned half-hour built-in hold.

Clocks have one more hold scheduled at T-minus 4 minutes. That pause will last 20 minutes during which time the final "go" for launch will be given. All remains targeted for liftoff at 9:12 a.m. local time (12:12 p.m. EDT; 1612 GMT) from Vandenberg Air Force Base, California.

The pre-fueling readiness poll of the launch team just completed by the launch conductor indicates all systems are "go" to proceed with the countdown this morning as planned. The ULA launch director and government mission director also gave their approvals as well.

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

Atlas launch conductor is briefing his team on procedures before entering into the final two hours of the countdown. A readiness check of the team members is next.

Workers have wrapped up all of their hands-on activities at the launch pad and cleared the area in advance of this morning's propellant loading and launch of the Atlas 5 rocket.

T-minus 2 hours and holding. The countdown has just entered the first of the planned holds over the course of the morning that will lead to the 9:12 a.m. PDT launch of the Atlas-Centaur rocket. This initial pause lasts 30 minutes, giving the team some margin in the countdown timeline to deal with technical issues or any work that is running behind. The final hold is scheduled to occur at T-minus 4 minutes.

Guidance system testing and the flight control operational checks are complete.

Final preps for the Centaur's liquid oxygen and liquid hydrogen systems have been performed. The S-band telemetry relay system communications checks are ongoing.

Launch team members say the first stage propulsion and hydraulic preps, internal battery checks and testing of the C-band system used to track the rocket as it flies downrange have been accomplished.

The gantry rollback and securing at the launch park spot is reported complete.

The mobile service tower is being secured in its launch position. The ground crew will get its doors closed, plus finish final buttoning up of pad equipment over the next hour before all workers clear the pad for the remainder of the countdown.

Today's launch will be the second Atlas 5 rocket to fly from Vandenberg's Space Launch Ccomplex 3-East pad. The site underwent an extensive overhaul, with construction occurring in 2004 and 2005, to accommodate the larger and more powerful Atlas 5 family of rockets. Some of the major modifications included:

• 30-foot extension to mobile service tower
• 20-foot exhaust duct depth increase
• 250-ton Fixed Launch Platform installed
• Significant ambient and cryogenic fluid ground system modifications
• Complete replacement of the Ground Command/Control/Communication system
• New and refurbished Launch Control/Mission Support Centers

Preps for the Atlas first stage liquid oxygen system and pneumatics, as well as Centaur liquid oxygen and liquid hydrogen systems have been completed.

The tower is clear of the vehicle as it continues to slowly roll away. Atlas 5 has been unveiled for launch, although the incredibly dense fog is keeping the rocket hidden this morning.

At the Space Launch Complex 3 pad, the mobile service gantry has been readied for its retraction away from the Atlas 5 rocket right on schedule this morning.

The 8-million-pound tower is wheeling back to its launch position a short distance from the 19-story-tall booster.

The structure was instrumental in assembling the rocket and payload during the pre-flight campaign.

The formal countdown sequence is underway and the Atlas-Centaur rocket has been powered for today's launch from Vandenberg Air Force Base in California. The launch team is running through routine testing and preps, as well as configuring pad systems as the clocks tick toward the 9:12 a.m. local time liftoff.

And a reminder that if you will be away from your computer but would like to receive occasional countdown updates, sign up for our Twitter feed to get text message updates on your cellphone. U.S. readers can also sign up from their phone by texting "follow spaceflightnow" to 40404. (Standard text messaging charges apply.)

As the countdown gets underway Sunday morning, the launch team will power up the rocket and begin standard pre-flight tests to prepare the Atlas 5 rocket for its weather satellite deployment mission.

Rollback of the mobile service tower from around the rocket is scheduled to start about five hours before launch.

Crews at the pad will make preparations to systems and equipment before the site is cleared of all personnel about two hours after tower rollback.

A planned hold begins when the count reaches T-minus 120 minutes. With five minutes remaining in 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 Atlas first stage and the Centaur upper stage about two hours before launch. 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 will give the team a chance to finish any late work and assess the status of the rocket, payload, Range and weather before proceeding into the last moments of the countdown.

Liftoff is targeted for 9:12 a.m. local time (12:12 p.m. EDT; 1612 GMT).

Seeing a rocket blast off is an impressive sight to behold. But the weather will decide whether anyone will be able to see a 19-story-tall Atlas 5 rocket thundering away from Vandenberg Air Force Base in California on Sunday.

In a recent interview, Col. Stephen Pluntze, commander of the Defense Meteorological Satellite Systems Group that oversees the weather satellite being launched aboard the Atlas, had this to say: "Yea, it is an exciting time. It is difficult to explain to folks what a satellite launch is like unless you are standing there. It is a pretty impressive sight, unless it is so foggy you can't see anything."

Well, it could end up being an invisible launch. Forecasters have issued a gloomy weather outlook calling for ground-hugging clouds and fog that threaten to spoil the view for spectators at the base during Sunday morning's 9:12 to 9:22 a.m. PDT launch window.

"Onshore flow throughout the night will push widespread marine layer stratus clouds well inland and light fog will reduce visibility to a mile or less," the launch forecast says.

The specifics include overcast conditions at 500 feet off the ground and fog, high cirrus clouds around 22,000 feet, northwesterly winds of 8 to 12 knots and a temperature between 53 and 56 degrees F.

The official odds of acceptable weather for launch stand at 80 percent. It's the high cloud cover that could pose a threat to violating the thick cloud rule.

But even if the view is ruined locally, spectators downrange could spot the rocket and its long fiery plume from the kerosene-fueled main engine soaring toward space.

Six years to the day after an Air Force weather observatory left behind its remarkable star-crossed history and finally flew into space, the aging craft's replacement will be sent aloft Sunday morning atop an Atlas 5 rocket from America's western launch center.

Liftoff from Vandenberg Air Force Base in California is targeted for 9:12 a.m. local time (12:12 p.m. EDT; 1612 GMT) at the opening of a brief 10-minute launch window.

It was October 18, 2003 when the Defense Meteorological Satellite Program F16 spacecraft roared away from Vandenberg atop a Titan 2 booster after multiple trips to the launch pad and countdowns spread across 33 months. The seemingly jinxed satellite had gotten within 28 seconds of blastoff in early 2001, but that day's scrub was just one chapter in the long saga of delays.

A full recap about the satellite's infamous hard luck can be read here, along with another article from the day DMSP F16 eventually launched.

The memories about trying to get the satellite into space come flooding back now that its successful mission transitions into a new phase. Having surpassed its design life, the Air Force is poised to launch a new spacecraft -- known as DMSP F18 -- to take over the role as leader in F16's orbit.

DMSP satellites orbit around the planet to collect global weather data for the U.S. military to use in planning operations across the world. The polar-orbiting satellites are built by Lockheed Martin with an expectation to last four years but normally operate much longer.

Sunday's launch, ironically scheduled on the sixth anniversary of the DMSP F16 liftoff, will deliver the fresh new weather-watcher into that craft's orbit. Flying south from the Vandenberg's Space Launch Complex 3 pad, the Atlas rocket and its Centaur upper stage will deploy the $500 million DMSP F18 satellite into its circular orbital perch 463 nautical miles high.

"F16 will be the one that this satellite replaces, although F16 will not stop working," said Col. Stephen Pluntze, Defense Meteorological Satellite Systems Group commander at Los Angeles Air Force Base.

The U.S. military has a constellation of two primary DMSP satellites and older backups working in space. Once the new DMSP F18 spacecraft is launched and checked out, it should be ready for full service by December as the lead bird in its distinct orbit. The DMSP F16 will remain in service, albeit as a secondary craft, for the remainder of its usefulness.

"You know, it would be nice to be able to wait until one breaks before you replace it, then you are not losing anything, you've used up one totally and then the next one comes online and it takes over the mission. There's really no way to predict when the ones up there are going to fail. If you waited until they fail, it takes quite a long time to get a satellite ready for launching and we don't wait on the pad with the satellite ready to go. We tend to launch them before they are needed but there's really no way around that," Pluntze said.

"It's a little bit of an art, not a science to figuring out when the older ones are old and when you need a new one. F16 is in decent shape. There were some improvements made to that satellite, so it's doing okay. But it's down now to its last gyroscope, which is what keeps the upside up and the downside down. So it is time to launch this one. The one that's up there won't break immediately, but it's getting to the point we realize it is time."

Today, the military is using four DMSP satellites ranging in age from the extraordinarily long-lived F13 launched in 1995 to the youngest, F17, deployed in 2006. The quartet is separated into pairs operating in two different orbits. Their instruments provide visible and infrared imagery of clouds, day or night, plus measure winds, soil moisture, ice and snow coverage, pollution, fires and even spot dust storms in Iraq.

"We only need one satellite in each orbit to be working. We're lucky that we have more than that. So in this orbit we'll have F15, F16 and F18, after it gets up. The other orbit we have F13 and F17," Pluntze said.

The U.S. military has been operating weather satellites for decades. Rejuvenating the constellation with new observatories ensures the continued flow of data for long-term forecasting and real-time inputs to leaders on the battlefield.

"This is an incredibly important mission for our nation. The team is very capable of launching successfully. Every possible aspect of the mission has been thoroughly vetted and we are absolutely confident that we are going to proceed toward a launch success on the 18th of October. But bear in mind if we are not ready on the 18th, we will launch only when the spacecraft and launch vehicle are fully prepared to launch," said Col. Michael Moran, the Atlas Group commander and the mission director for Sunday's launch.

"Little happens on today's battlefield without a very clear picture of the weather. Weather information from space systems provides a unique view of the globe, supporting not just military needs but those of the broader national security community and, in fact, the global community. DMSP is truly an amazing spacecraft that will provide meteorological, oceanographic and solar-terrestrial physics to satisfy these critical needs."

Added Pluntze: "It is a Sunday morning launch. I would encourage everybody who would like to to take a weekend trip with their families and have a great morning watching Air Force hardware make it up into space."