The United States' latest weather observatory successfully flew into geostationary orbit and got a new name Tuesday, completing a series of stair-step altitude raising maneuvers that followed its launch earlier this month atop a Delta 4 rocket from Cape Canaveral.

The Geostationary Operational Environmental Satellite was built and launched under the name of GOES P. But following NOAA tradition of renaming its satellites upon reaching the proper orbit, the craft became GOES 15.

The craft is designed to fly 22,300 miles above the planet and constantly track conditions for meteorologists from orbital vantage points above either the eastern or western sides of the Americas.

Some five firings of the satellite's liquid-fueled engine, producing 100 pounds of thrust, circularized the orbit after being delivered by the launcher into an elliptical transfer orbit. The burns began on March 7.

The power-generating solar array will be unfurled Wednesday, the long magnetometer boom deploys Saturday and the coverings on the imager and sounder instruments should be jettisoned next Tuesday. Handover of control from satellite-maker Boeing to NASA is scheduled for next Wednesday.

The space agency plans months of instrument activation work and extensive testing that's expected to last through August. If all goes well, GOES 15 will be given to NOAA for use in the network of weather-watching satellites. It'll initially be placed into orbital storage as a spare for NOAA.

"Our geostationary satellites are the nation's weather sentinels in the sky," said Jane Lubchenco, under secretary of commerce for oceans and atmosphere and NOAA administrator. "With more than 35 million Americans living in hurricane prone areas and more than 1,000 tornadoes touching down in the U.S. annually, we need the reliable, accurate data that these satellites provide."

GOES 15's test location is above the equator at 89.5 degrees West longitude. Its storage slot will be 105 degrees West.

The Delta 4 rocket has accomplished a critical three-peat for the nation in flawless style, successfully capping a series of repetitive but highly important U.S. weather satellite launches with a beautiful blastoff at nightfall Thursday.

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VIDEO: THE FULL LAUNCH EXPERIENCE PLAY
VIDEO: DELTA 4 BLASTS OFF WITH GOES P PLAY | HI-DEF
VIDEO: LAUNCH REPLAYS: VAB ROOF CAMERA PLAY | HI-DEF
VIDEO: LAUNCH REPLAYS: FROM SHUTTLE PAD PLAY | HI-DEF
VIDEO: LAUNCH REPLAYS: CAUSEWAY ZOOMED VIEW PLAY | HI-DEF
VIDEO: LAUNCH REPLAYS: CAUSEWAY WIDE-ANGLE VIEW PLAY | HI-DEF
VIDEO: LAUNCH REPLAYS: PLAYALINDA BEACH TRACKER PLAY | HI-DEF
VIDEO: LAUNCH REPLAYS: UCS 3 TRACKING CAMERA PLAY | HI-DEF
VIDEO: LAUNCH REPLAYS: MOBILE SERVICE TOWER CAMERA PLAY
VIDEO: LAUNCH REPLAYS: DELTA OPERATIONS CENTER PLAY
VIDEO: LAUNCH REPLAYS: WEST LIGHTNING TOWER PLAY
VIDEO: LAUNCH REPLAYS: EAST LIGHTNING TOWER PLAY

VIDEO: RECAP OF THE ROCKET'S LAUNCH CAMPAIGN PLAY | HI-DEF
VIDEO: RECAP OF THE SATELLITE'S LAUNCH CAMPAIGN PLAY | HI-DEF
VIDEO: TOWER ROLLBACK REVEALS ROCKET FOR LAUNCH PLAY | HI-DEF
VIDEO: OVERVIEW OF GOES WEATHER OBSERVATORIES PLAY | HI-DEF
VIDEO: WATCH THE PRE-LAUNCH NEWS CONFERENCE PLAY

VIDEO: GOES P TRUCKED TO THE LAUNCH PAD PLAY | HI-DEF
VIDEO: SPACECRAFT ENCAPSULATED IN NOSE CONE PLAY | HI-DEF
VIDEO: MOVING THE GOES P SATELLITE AROUND PLAY | HI-DEF
VIDEO: CLEANROOM INTERVIEW WITH NOAA MANAGER PLAY | HI-DEF
VIDEO: CLEANROOM INTERVIEW WITH NASA MANAGER PLAY | HI-DEF

VIDEO: SOLID BOOSTERS ADDED TO DELTA 4 PLAY | HI-DEF
VIDEO: DELTA 4 ERECTED AT THE LAUNCH PAD PLAY | HI-DEF
VIDEO: ROCKET ROLLED OUT OF THE HANGAR PLAY | HI-DEF
VIDEO: FIRST AND UPPER STAGES CONNECTED PLAY | HI-DEF

VIDEO: UP-CLOSE AND PERSONAL WITH GOES P PLAY | HI-DEF
VIDEO: CHECKING OUT SPACECRAFT IN CLEANROOM PLAY | HI-DEF
VIDEO: SATELLITE EMERGES FROM SHIPPING CRATE PLAY | HI-DEF
VIDEO: GOES P SATELLITE LANDS IN FLORIDA PLAY | HI-DEF

VIDEO: THE UPPER STAGE IS READY TO FLY PLAY | HI-DEF
VIDEO: UPPER STAGE TO DELTA OPS CENTER PLAY | HI-DEF
VIDEO: UNPACKING DELTA'S UPPER STAGE PLAY | HI-DEF
VIDEO: SOLID ROCKET MOTOR RECEIVED PLAY | HI-DEF
VIDEO: FIRST STAGE ARRIVES AT THE CAPE PLAY | HI-DEF
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Here's some additional post-launch quotes from various press releases:

"Pratt & Whitney Rocketdyne congratulates Boeing, ULA, NASA and NOAA for the successful launch of GOES P, and is proud to continue our vital role in helping boost technology that will monitor unpredictable weather patterns," said Craig Stoker, program manager at Pratt & Whitney Rocketdyne for the RS-68 main engine.

"The RL10B-2 performed exactly as expected, and we are honored to supply the ride for this satellite that will be used by scientists in their mission to provide early warning during severe weather conditions," said Christine Cooley, RL10 program manager at Pratt & Whitney Rocketdyne.

"It's a great day for NASA and NOAA, as this last launch completes the spacecraft in the GOES N-P series," said Andre Dress, the NASA GOES deputy project manager. "It means the hard work and dedication from this team during the past 12-plus years all has been worth it. Our review of the spacecraft and launch vehicle data shows that GOES P is in a nominal transfer orbit with all spacecraft systems functioning properly."

The next launch of a Delta 4 rocket from Cape Canaveral is planned for mid-May carrying the first in a new era of Global Positioning System satellites for the U.S. Air Force.

"This safe and successful launch by this amazing multi-agency team of professionals will help ensure vital atmospheric and environmental information will be sent to users enhancing weather forecasts and climate studies," said Col. Ed Wilson, 45th Space Wing commander at the Cape. "This mission showcases why the 45 Space Wing continues to be the world's premiere gateway to space."

United Launch Alliance Delta 4 rockets have successfully deployed all three new satellites for the nation's new weather observing system -- GOES N, O and P.

"This has been a tremendous nearly four-year partnership to place all three GOES satellites in their proper orbit," said Jim Sponnick, United Launch Alliance's vice president, Delta Product Line. "ULA congratulates Boeing and its NASA and NOAA customers for the successful launch of GOES P. The GOES series will improve weather forecasting across the globe. The weather disasters of the past five years across the world have clearly shown how important these satellites are to all of humanity."

T+plus 4 hours, 21 minutes. SPACECRAFT SEPARATION! The Geostationary Operational Environmental Satellite P has been deployed into orbit from the United Launch Alliance Delta 4 rocket's upper stage, completing tonight's successful ascent.

The 7,000-pound spacecraft, built by The Boeing Company, is a next generation weather satellite that will be ready to replace one of the nation's older observatories in the coming years.

"We're excited about having the best that this nation has to offer in orbit. That's huge," said Andre Dress, NASA's deputy project manager.

The craft will spend the next two weeks performing planned orbital circularization burns to reach geostationary orbit 22,300 statute miles above the planet. It will be parked at 90 degrees West longitude over the equator for testing.

Boeing controls the initial operations of the satellite. After getting into geostationary orbit and unfolding the solar array and appendages, the company will complete early testing and give the satellite to NASA around March 24. The space agency plans five months of rigorous checkout before handing the spacecraft over to NOAA in mid-August for official use.

The first visible image from the satellite is expected on March 31 and the initial shot of the Sun from the Solar X-ray Imager should arrive on April 17.

After the test period is completed, the satellite will be relocated to orbital storage around 105 degrees West.

T+plus 4 hours, 18 minutes. The rocket has achieved a 30-degree per second roll rate as planned.

T+plus 4 hours, 17 minutes. Spin-up of the rocket stage has started in preparation for releasing GOES P about four minutes from now.

T+plus 4 hours, 12 minutes. The upper stage is performing maneuvers in pitch, yaw and roll to re-orient itself into the attitude for release of the satellite.

T+plus 4 hours, 11 minutes. Final burn complete! The RL10B-2 motor fired back to life for the third of three burns to send the GOES P spacecraft into the proper orbit.

T+plus 4 hours, 10 minutes. Good burn in progress.

T+plus 4 hours, 10 minutes. Ignition! The upper stage if firing once again. This burn will last just under a minute in duration.

T+plus 4 hours, 8 minutes. The upper stage of the Delta 4 rocket is nearing the end of its long coast upward away from Earth. The motor is preparing to burn its engine one more time to propel GOES P into the targeted geosynchronous transfer orbit.

T+plus 4 hours. The Delta 4 rocket is using a three-burn ascent profile. It is the sixth time in 12 missions of the Delta 4 family that the upper stage has performed three firings to boost payloads into high orbits.

For the GOES P spacecraft, this upcoming burn will raise the low point of the elliptical geosynchronous transfer orbit and reduce the inclination. With the launch vehicle performing these adjustments, the satellite can preserve its onboard maneuvering fuel for added life.

T+plus 3 hours, 30 minutes. Now 40 minutes away from engine re-start on the second stage. In preparation for that event, the rocket will complete the BBQ thermal roll at T+plus 3 hours, 58 minutes and begin maneuvering itself into the proper orientation for ignition. The burn position should be achieved by T+plus 4 hours, 6 minutes. Then, the stage will start a system chilldown before firing the engine with cryogenic fuel and use its tiny thrusters to settle the propellants in the tanks.

Ignition occurs at T+plus 4 hours, 10 minutes for a 56-second firing. Spacecraft separation happens at T+plus 4 hours, 21 minutes.

We'll pass along confirmation about the launch events as they become available.

Check out the launch photo gallery from the NASA Causeway viewing location.

T+plus 2 hours, 30 minutes. The rocket is soaring away from Earth in its current egg-shaped orbit. Based on the pre-flight plan, the orbit should extend from about 125 statute miles at its closest point to 21,263 statute miles at the furthest. The upcoming engine firing at 11:07 p.m. EST will occur as the rocket nears apogee. The burn lasts just 56 seconds, but will raise the orbit's low point to 4,115 miles, increase the high point to 21,858 statute miles and reduce inclination closer to the equator.

Deployment of GOES P from rocket to complete the launch is expected at 11:18 p.m. EST.

T+plus 1 hour, 38 minutes. "Only 89 calendar days have passed since our last launch making this campaign the shortest time between two consecutive Delta 4 launches from the same pad," says Capt. John "JJ" McAfee of the Air Force's 5th Space Launch Squadron and the Delta 4 Flight Mission Lead.

"Over the holiday season and through this successful launch, the Delta launch team overcame numerous challenges, streamlined our processes, and elevated our partnerships to the next level."

T+plus 42 minutes. To recap, the Delta 4 rocket carrying the GOES P weather satellite launched from Cape Canaveral's Complex 37 at 6:57 p.m. EST after a 40-minute delay to assess some red alarms and await acceptable upper level wind conditions.

All appeared to go smoothly during the ascent and no problems were reported by the telemetry folks.

The rocket is now coasting toward a point about 20,000 statute miles above the Indian Ocean where the third and final burn is planned at T+plus 4 hours and 10 minutes.

T+plus 39 minutes. The rocket has started the planned thermal-controlling roll program of 1.3 degrees per second.

T+plus 30 minutes. To see the track the rocket is following this evening, click here.

T+plus 28 minutes. The rocket has just entered a three-hour, 43-minute coast period before the final engine burn to deliver GOES into the desired orbit this evening.

T+plus 27 minutes, 9 seconds. SECO 2. The second of three firings by the upper stage during today's launch has been completed.

T+plus 26 minutes, 55 seconds. Good chamber pressures and steering continues.

T+plus 26 minutes, 23 seconds. The rocket is 116 miles in altitude, 5,099 miles downrange, traveling at 31,532 feet per second.

T+plus 26 minutes, 5 seconds. About one minute left in this burn by the Delta 4 rocket's upper stage.

T+plus 25 minutes, 30 seconds. This burn injects the rocket into a highly elliptical orbit stretching over 21,000 statute miles at its furthest point.

T+plus 24 minutes, 45 seconds. This burn will last just over four minutes in duration.

T+plus 24 minutes, 20 seconds. The engine is performing well.

T+plus 23 minutes, 50 seconds. Good engine chamber pressure reported.

T+plus 23 minutes, 14 seconds. Ignition! The RL10B-2 engine, fed by liquid hydrogen liquid oxygen, has been reignited to propel GOES P into an intermediate orbit.

T+plus 21 minutes, 30 seconds. The initial orbit achieved hit the expected targets.

T+plus 20 minutes. During this time of the flight, the upper stage maneuvers itself into the proper attitude for engine restart.

T+plus 17 minutes. The vehicle is now in a coast mode before the next firing of the upper stage engine. Ignition of the RL10 engine is now six minutes away.

T+plus 12 minutes, 41 seconds. SECO 1. Confirmation that the upper stage engine has shut down after the first of three planned firings to inject the GOES spacecraft into geosynchronous transfer orbit.

T+plus 11 minutes, 45 seconds. The upper stage's the RL10 engine working well, still firing as planned to reach a low-altitude parking orbit this evening.

T+plus 11 minutes, 20 seconds. The vehicle's steep climb leveled off as it gains speed toward orbital velocity. Delta is 128 miles in altitude, 1,459 miles downrange from the launch pad.

T+plus 10 minutes, 35 seconds. The RL10 engine is burning a mixture of liquid oxygen and liquid hydrogen cryogenic propellants. Chamber pressures still look good.

T+plus 9 minutes, 5 seconds. Delta is 134.9 miles in altitude, 1,053 miles downrange from the launch pad.

T+plus 8 minutes, 40 seconds. About four minutes remain in this firing of the upper stage to place the vehicle into an initial parking orbit around Earth.

T+plus 8 minutes. It's a smooth ride with good pitch and yaw control on the upper stage, telemetry shows.

T+plus 7 minutes, 30 seconds. Delta is 129.7 miles in altitude, 751 miles downrange from the launch pad.

T+plus 6 minutes, 29 seconds. Delta is 119.2 miles in altitude, 577 miles east of the launch pad.

T+plus 6 minutes, 15 seconds. First stage flight events occurred very close to planned times.

T+plus 5 minutes, 45 seconds. Delta is 107.7 miles in altitude, 457 miles east of the launch pad.

T+plus 5 minutes, 30 seconds. Good chamber pressure data being reported from the RL10 engine as it thrusts to reach orbit.

T+plus 5 minutes, 7 seconds. The protective payload fairing enclosing the GOES satellite atop the rocket has separated.

T+plus 4 minutes, 51 seconds. The cryogenic RL10B-2 upper stage engine has ignited!

T+plus 4 minutes, 35 seconds. The Common Booster Core first stage and the attached interstage have been separated in one piece from the Delta 4's upper stage. The upper stage engine's extendible nozzle is dropping into position.

T+plus 4 minutes, 27 seconds. MECO! Main engine cutoff confirmed as the RS-68 powerplant shuts down.

T+plus 4 minutes, 3 seconds. Delta is 66.9 miles in altitude, 195 miles east of the launch pad.

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

T+plus 3 minutes, 35 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. The main engine continues to perform well, consuming its liquid hydrogen and liquid oxygen propellants.

T+plus 2 minutes, 50 seconds. Altitude 38 miles, 62.7 miles downrange.

T+plus 2 minutes, 30 seconds. A spectacular sight in the night sky as the Delta 4 rocket heads to space with GOES P.

T+plus 2 minutes. Delta is 2.26 miles in altitude, 24.2 miles downrange from the launch pad.

T+plus 1 minute, 42 seconds. Solid motor separation! The spent boosters have been shed from the first stage. Delta 4 continues powering its way toward space on the thrust generated by the RS-68 main engine.

T+plus 1 minute, 37 seconds. The twin solid rocket boosters have burned out of their propellant. Standing by for jettison.

T+plus 60 seconds. Now passing through the region of maximum aerodynamic pressure as the vehicle accelerates through the lower atmosphere.

T+plus 50 seconds. The launcher has broken through the sound barrier.

T+plus 30 seconds. The Delta 4 rocket is climbing away from the planet with its main engine firing at full throttle and the two strap-on boosters giving a powerful extra kick.

T-minus 10, 9, 8, sequencer now controlling, T-minus 6, 5, main engine start, 3, 2, 1, booster ignition and LIFTOFF! Liftoff of the Delta 4 rocket in pursuit of a successful three-peat in launching the GOES weather observatories for the nation!

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

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

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

T-minus 38 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, 35 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, 5 seconds. The systems of the first and upper 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 GOES P weather observatory. Liftoff is set to occur at 6:57 p.m. EST (2357 GMT) from pad 37B at Cape Canaveral Air Force Station.

Winds aloft are declared "go" and the launch director has given approval to resume the count for liftoff at 6:57 p.m. EST!

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 final readiness polls of the launch team and mission managers have been completed. No technical problems are being worked and all rocket, spacecraft and ground systems appear to be "go" for liftoff at 6:57 p.m. EST.

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The red alarms have been examined and cleared with no impact to the launch.

NEW LAUNCH TIME. Liftoff has been pushed back to 6:57 p.m. EST to accommodate additional time needed to work the upper level wind data.

A NASA spokesman says the alarms were likely not caused by any problems with the rocket. But the team continues to assess. Also, it is not clear that upper level wind information will be ready to support a 6:47 p.m. EST launch.

Today's available launch opportunity extends to 7:17 p.m. EST.

There's been no confirmation on what the red alarms were associated with. And soon after the extended hold was ordered, the upper level winds were declared red again.

NEW LAUNCH TIME. The earliest that launch could occur is 6:47 p.m. EST. That's based on the time the next weather balloon data would be received and processed to give acceptable upper level wind conditions.

The upper level wind situation has gone red again, the launch director just announced.

The upper level winds were confirmed acceptable for the first 10 minutes of the window. If this delay lasts more than that, engineers will have to re-verify the winds aloft.

HOLD EXTENDED. The team is looking at red alarms that sounded, delaying the liftoff of Delta 4 rocket at least a few minutes.

The final readiness poll of the launch team just occurred. However, a couple of members voiced a "not ready." Apparently there has been a red alarm that the team is evaluating.

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

• The 348th Delta rocket launch since 1960
• The 12th Delta 4 rocket mission since 2002
• The 10th Delta 4 rocket launch from Cape Canaveral
• The 5th Medium+ 4,2 configuration to fly
• The 5th Delta 4 under the ULA banner
• The 1st Delta launch this year
• The 13th geostationary weather satellite launch on Delta
• The 3rd GOES spacecraft flown on Delta 4

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

The upper level winds are declared "go" for liftoff during the opening of today's launch window!

A load relief file based on the upper level winds is being transmitted to the Delta 4 rocket's flight computer. This program informs the rocket on the wind conditions it can expect to see during ascent.

T-minus 5 minutes and holding. The countdown has entered a planned 15-minute hold, but the upper level winds will dictate if additional time needs to be added.

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.

Engineers continue to work the upper level wind situation and developing a suitable flight profile to handle the conditions today.

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Now 30 minutes away from the opening of today's launch window that runs from 6:17 to 7:17 p.m. EST.

You can watch and listen to the Delta 4 rocket's launch on your iPhone or iPod Touch by going here: http://iphone.livestream.com/spaceflightnowmobile

Clear skies, ground winds in the low teens and a temperature of 55 degrees are the current weather conditions at the launch pad. But it is upper level winds that are a concern. The maximum winds are 160 knots at 37,500 feet in altitude.

Evaluation of the last weather balloon data showed the conditions aloft would exceed the rocket's structural loads slightly. Additional balloons and other flight profile options are available for engineers to find a safe way to launch the rocket today.

The ULA launch team and management are guiding the countdown from the Delta Operations Center, located about 9,200 feet from the pad. The engineers overseeing the rocket and ground systems are located on the third floor and the Mission Directors Center room is on the fourth floor. Both rooms have a view of pad 37B and the Delta 4 rocket out their windows. Other rooms are also set up for engineering support.

The DOC was formerly built to support the Titan-Centaur program but was refurbished to support Delta 4.

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 6:17 p.m., the opening of today's 60-minute launch window.

The first stage Common Booster Core slews and the commanding tests for the strap-on solid rocket motors were run, wrapping up the pre-launch program.

The upper stage engine steering checks have been completed. The first stage tests are next.

Now 60 minutes away from the launch of the GOES P weather observatory aboard a Delta 4 rocket from Cape Canaveral, Florida.

"For NASA, what could be more exciting than to do this for a project, right? To launch a satellite at the end of all your hard work and labor. For GOES P, it's not just this satellite, it's really the culmination of all the work that we've done building GOES N, GOES O and GOES P. Over the last 12 years, we've been working on this. So you are seeing the fruits of that labor here. There's a lot of talented people that have been working on this project," said Andre Dress, GOES P deputy project manager from NASA's Goddard Space Flight Center.

The engine steering checks for the RS-68 main engine and RL10 upper stage engine, plus commanding tests with the solid rocket motors is underway.

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

The safety checks have been completed satisfactorily.

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

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

The thermal insulation inspections have been completed and the rocket remains in good shape following fueling.

The launch team is entering the last 90 minutes of the countdown. With fueling of the Delta 4 rocket completed, this phase of the count is mostly quiet. Engineers 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 6:17 p.m. EST.

The upper level winds are the chief worry at this hour. The latest weather balloon now shows "no go" conditions. But further balloons will be dispatched as the countdown continues and engineers will use that data to chose a good flight profile based on those conditions aloft.

The radio frequency link checks between the rocket and ground have been completed and verified satisfactory.

Just inside two hours from launch as the countdown remains on schedule.

Upper stage liquid oxygen topping has commenced. That puts all four cryogenic fuel tanks aboard the Delta 4 rocket in topping mode.

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

The launch team is not tracking any technical issues with the rocket. The weather conditions are favorable and the upper level winds, which were a worry going into the launch attempt, are within limits too.

The upper stage liquid oxygen filling has been completed. All four of the vehicle's cryogenic tanks are loaded.

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The topping mode has started for the upper stage's liquid hydrogen tank. The first stage's LOX and LH2 tanks are in topping as well.

You can watch and listen to the Delta 4 rocket's countdown on your iPhone or iPod Touch by going here: http://iphone.livestream.com/spaceflightnowmobile

The first stage liquid hydrogen tank is now entering the topping phase after valve tests.

Now three hours till launch. The Delta 4 rocket's Common Booster Core first stage has been loaded with supercold liquid oxygen and liquid hydrogen. The upper stage filling remains in progress.

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 receives its cryos from the middle swing arm that extends from the Fixed Umbilical Tower to the front-side of the rocket.

The chilldown of the upper stage liquid oxygen system is reported complete, clearing the way for loading the rocket's tank with 4,500 gallons. This is the last of the rocket's four cryogenic supplies to be filled in today's countdown to launch.

Upper stage liquid hydrogen tank in fast-fill mode has finished as well. Checks will performed before topping commences.

Fast-fill loading of the first stage liquid hydrogen tank has been completed. Vent and relief checks will be performed shortly.

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

Meanwhile, the stage's liquid hydrogen tank continues to be loaded with 10,000 gallons of propellant for the RL10 engine.

Extensive video coverage of the Delta 4 rocket and GOES P satellite during their pre-launch preparations at Cape Canaveral is available in our archive for Spaceflight Now+Plus users. Standard definition clips are posted here. We also have a large collection of stunning high definition video here.

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

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The first stage liquid oxygen loading just finished. The tank has been loaded with its supercold oxidizer that is chilled to Minus-298 degrees F. Topping will be completed as the count rolls on.

Now four hours away from launch. The first stage liquid oxygen tank is 85 percent full.

The countdown activities are proceeding as planned at Cape Canaveral's Complex 37 for today's launch of the Delta 4 rocket with the GOES P weather satellite. Filling of the first stage with liquid oxygen and liquid hydrogen is continuing out at the launch pad, and early preps for the upper stage loading have begun.

First stage liquid hydrogen tanking operation is switching from "slow-fill" to "fast-fill" mode.

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 will be loaded with 40,000 gallons of supercold LOX.

You can watch and listen to the Delta 4 rocket's countdown on your iPhone or iPod Touch by going here: http://iphone.livestream.com/spaceflightnowmobile

The start of liquid hydrogen fueling of the first stage is now confirmed. Some 110,000 gallons of LH2 will fill the rocket's tank.

The cold gas chilldown conditioning of the liquid hydrogen system has been accomplished. Liquid hydrogen propellant will begin 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, 27 seconds of the launch.

The first stage liquid oxygen chilldown is complete. Fueling will begin 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.

Checks of the C-band beacon has been completed. This system is used in tracking the rocket as it travels downrange.

The hydrogen system's cold gas chilldown conditioning is underway.

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 has begun. 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 the formal "go" to press ahead with fueling as planned.

T-minus 5 hours, 15 minutes and counting! The Terminal Countdown begins now for today's flight of the United Launch Alliance Delta 4 rocket with the Geostationary Operational Environmental Satellite P.

The countdown has one planned built-in hold at T-minus 5 minutes lasting some 15 minutes, leading to liftoff at 6:17 p.m. EST (2217 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.

Live streaming video of the Delta 4 rocket can be accessed on your iPhone or iPod Touch by going here: http://iphone.livestream.com/spaceflightnowmobile

The launch team has been polled to verify all consoles are manned and ready to begin the Terminal Countdown when this hold ends at 12:44 p.m. A briefing on countdown procedures is now underway.

Two technical issues are being addressed at this time.

The rocket's avionics have been turned on for launch and the interrogation checks of the C-band beacon used for tracking the vehicle during its flight downrange is now underway.

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 12:47 p.m. EST, the Terminal Countdown phase of today's launch operation will begin.

Check out today's gantry rollback photo gallery taken by Spaceflight Now's Justin Ray and Stephen Clark at Complex 37.

The 330-foot tall mobile service tower has been retracted from the Delta 4 rocket at Cape Canaveral's pad 37B for today's launch that will place the GOES P weather satellite into Earth orbit.

The wheeled structure was moved along rail tracks just to its launch position about the length of a football field away from the rocket just after 8 a.m. EST. The 9-million pound tower shielded the Delta from the elements during the two-month 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 6:17 p.m. EST, the opening of a 60-minute window that extends to 7:17 p.m. EDT (2317-0017 GMT).

Nestled inside the nose cone of a Delta 4 rocket at Cape Canaveral's pad 37B rests the GOES P weather satellite that awaits its ride into orbit Thursday evening.

"We had a good launch readiness review today. The launch vehicle and the satellite are ready to go," said Kris Walsh, commercial programs manager at rocket-maker United Launch Alliance.

The available window for the launch extends from 6:17 to 7:17 p.m. EST. The precise period is driven by the orbital requirements of the payload.

Launch day activities will begin in the predawn hours preparing for retraction of the 330-foot mobile service tower away from the Delta 4 vehicle. The gantry is used to gain access to the rocket during pre-flight work, plus serve as a protective structure to shield the booster from adverse weather conditions during its stay at the pad.

The Terminal Countdown will begin ticking at 12:47 p.m. EST, leading to the multi-hour process of loading the Delta 4's Common Booster Core first stage and the second stage with supercold liquid oxygen and liquid hydrogen propellants.

Testing of communications links between the rocket and Air Force Eastern Range will occur after fueling is accomplished. Steering checks of the first stage RS-68 engine and second stage RL10 powerplant are on tap in the last hour of the count.

A 15-minute build-in hold is slated for T-minus 5 minutes, during which time teams will go through final polling to grant clearance to launch. The Delta 4 will transition to internal power as the count resumes, ordnance will be armed and the propellant tanks pressurized as clocks target the main engine ignition time at T-minus 5.5 seconds.

One issue that will be watched is the upper level wind conditions. Launch weather officer Joel Tumbiolo said the core of the jet stream is coming across Florida, bringing winds of 130 knots and greater overhead around 40,000 feet in altitude.

A long series of weather balloons will be dispatched throughout the countdown to measure the speed and direction of the winds as they evolve over time, giving engineers the data they need to determine if the rocket can handle the conditions aloft.

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Fixes to two glitches are being completed and the Delta 4 rocket is aiming for a sunset blastoff Thursday carrying the nation's next geostationary weather observatory.

The launch was pushed back two days so workers could replace a faulty valve in the strap-on solid rocket booster steering system and a quick disconnect in the propellant plumbing.

Managers will get together Wednesday for the Launch Readiness Review to assess the status of work and give approval to proceed into Thursday's countdown.

Weather forecasters are predicting ideal conditions during Thursday's 60-minute launch window that opens at 6:17 p.m. EST (2317 GMT).

The outlook includes partly cloudy skies, good visibility, a temperature around 53 degrees F and northwesterly winds of 12 to 18 knots. The limit from that direction is 20 knots.

Launch of the GOES P weather observatory aboard a Delta 4 rocket has been postponed to Thursday evening from the Cape, a 24-hour slip to replace a component in the fuel-delivery system from the pad to the vehicle.

"During launch processing inspections and reviews Sunday, mission managers determined that a quick disconnect in a line, which flows fuel to the rocket on launch day, needed to be removed and replaced. This work, in addition to the normal processing timeline, required the launch to move one day to March 4," officials announced in a statement Saturday morning.

"A faulty steering control valve located on a solid rocket motor discovered Friday was replaced and the resulting system checks are in-process," officials added.

"The Delta 4 and GOES P spacecraft are safe and secure."

Thursday's launch window stretches from 6:17 to 7:17 p.m. EST. The weather outlook is 80 percent favorable that day.

Although space launches are never routine, the Delta 4 rocket team is working toward repeated success Wednesday night during the third carbon-copy mission conducted in recent years to deliver national weather satellites into orbit.

Liftoff from Cape Canaveral's Complex 37 at the Florida spaceport is scheduled during a one-hour window extending from 6:18 to 7:18 p.m. EST.

Weather forecasters are predicting an 80 percent chance of acceptable conditions to get the rocket off the ground. Gusty winds above the 20-knot limit pose the only concern.

The outlook calls for a few low and some scattered high clouds, good visibility, northwesterly winds of 15 gusting to 22 knots and a temperature around 54 degrees F.

The Flight Readiness Review was held Thursday and the mission dress rehearsal for officials to practice the launch day procedures occurred Friday. The Launch Readiness Review to give the formal approval to head into the countdown will take place Tuesday.

Following flawless launches of its two sister satellites in 2006 and last summer aboard Delta 4 rockets, the Geostationary Operational Environmental Satellite P, or GOES P, now stands ready to join the orbiting constellation as a spare.

This satellite is the third in an updated series of weather-watching spacecraft with sharper vision and extended life to provide constant observations of clouds, atmospheric conditions and severe weather like hurricanes.

The GOES program has a long history of providing the weather imagery seen daily during news broadcasts, allowing meteorologists to monitor conditions and forecast the future across North America.

"We all look forward to those pictures every night on TV to see where the storms are and where they are heading. That is GOES' main job," said Tom Wrublewski, NOAA's technical acquisition manager.

GOES P will be placed into a geosynchronous transfer orbit by the Delta rocket, then maneuvered by its onboard engine into a circular geostationary orbit 22,300 miles above the equator where it can match Earth's rotation and appear parked in the sky. It will be thoroughly tested and then put into storage mode to await the upcoming job of replacing an aging satellite.

"One of the amazing things about these satellites is you don't often think about it but they fly out at 22,300 miles in space. That's about equivalent to flying coast to coast over seven times, to put it into perspective. And we're able to locate storms within (1.25 miles) with this fantastic platform. It is really remarkable," Wrublewski said.

The two primary satellites currently in operation are GOES 11 in the western coverage zone and GOES 12 in the east. But the nine-year-old GOES 12 will be repositioned in April to focus on South America for the rest of its useful life. The GOES 13 satellite, which was launched in 2006 under the name GOES N, will be brought out of orbital storage and placed into service as the new eastern craft.

GOES O, renamed GOES 14 after rocketing into orbit last June, now awaits the call for duty. Projections show it replacing GOES 11 at the end of 2011.

That will make GOES P, which will be re-branded GOES 15 after a successful delivery to orbit, the constellation's main spare. NOAA wants backup satellites already in space and ready to take over within 72 hours of a primary craft suffering a problem or failure.

GOES P is being launched now since the opportunity is available on the Delta 4 rocket's schedule and there's no real harm in storing the craft in orbit. It's also cheaper than paying for care-taking on the ground.

"We are very anxious to get this satellite launched and maintain our continuity of service," Wrublewski said.

The long-range expectations foresee the satellite remaining the spare until replacing GOES 13 (formerly called GOES N) sometime in 2015. But any surprise glitch aboard one of the operational birds would require GOES P coming to the rescue far sooner.

Boeing built the GOES N, O and P satellites and oversees the launches under a commercial arrangement with the government.

A Delta 4 Medium+ vehicle will be used in launching the 7,000-pound spacecraft. This particular "4,2" version of United Launch Alliance-built rocket features a four-meter payload fairing and two strap-on solid rocket boosters.

Senior managers will gather for the final readiness assessments and hold the pre-launch news conference on Tuesday. Countdown operations begin early Wednesday with rollback of the mobile service gantry from around the rocket.

Watch this page for live coverage throughout the countdown and launch!

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The swapout of a faulty valve has delayed the Delta 4 rocket launch of a new weather satellite by a day. Liftoff has been reset for Wednesday evening, which is when better weather conditions are expected anyway.

"During close out procedures on the vehicle Friday, mission managers determined that a steering control valve on one of the solid rocket motors was faulty and required removal and replacement," officials announced in a statement Saturday morning.

"This additional work, in addition to the normal processing timeline, requires the launch to move one day."

Wednesday's launch window stretches from 6:18 to 7:18 p.m. EST.

Weather forecasters had given slim odds that the launch would have happened Tuesday due to thunderstorms and high winds passing through the area. Much improved conditions are expected on Wednesday evening.

Meteorologists are forecasting challenges imposed by Mother Nature for Tuesday's planned launch of a U.S. weather satellite aboard a Delta 4 rocket from Cape Canaveral, Florida.

Liftoff from pad 37B is scheduled to occur during a one-hour window stretching from 6:19 to 7:19 p.m. EST (2319-0019 GMT). The launch opportunity begins just minutes before sunset.

But the outlook predicts an 80 percent chance that conditions will violate the strict launch weather rules due to thunderstorms and high winds.

The official forecast issued Friday morning says: "Large scale upper level pattern will consist of a deep low pressure trough over the eastern Continental U.S. At the surface, the next is a series of low pressure systems will develop over the western Gulf of Mexico and travel quickly across northern Florida on Tuesday bringing a cold front through the area during the launch countdown. This system will bring strong surface winds, showers and thunderstorms across the area. Several weather launch commit criteria rules will be at risk of violation in addition to ground level pre-liftoff and liftoff winds."

The specifics during the launch window include broken decks of low- and mid-level clouds, overcast skies at 25,000 feet, showers and thunderstorms in the area, 7 miles of visibility, southwesterly winds of 18 peaking to 25 knots and a temperature around 63 degrees F.

The forecast improves dramatically on Wednesday evening, if the launch gets pushed back 24 hours. There's only a 20 percent chance of ground winds being a problem then.

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.)