BY JUSTIN RAY

Follow the countdown and launch of the Boeing Delta 2 rocket with the NOAA-N polar orbiting weather satellite. Reload this page for the very latest on the mission.

Additional coverage for subscribers:
VIDEO: THE DELTA ROCKET BLASTS OFF WITH NOAA-N QT
VIDEO: LONGER-LENGTH CLIP OF TODAY'S LAUNCH QT
VIDEO: LIFTOFF AS SEEN FROM PAD FRONT CAMERA QT
VIDEO: INFRARED TRACKING CAMERA FOLLOWS ROCKET QT
VIDEO: UMBILICALS YANK AWAY FROM DELTA AT LIFTOFF QT
VIDEO: SATELLITE AND ROCKET LAUNCH PREPS NARRATED QT

VIDEO: LAST WEEK'S COUNTDOWN SCRUBBED BY PAD GLITCH QT
VIDEO: WATCH THE PRE-LAUNCH NEWS BRIEFING DIAL-UP | BROADBAND
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FRIDAY, MAY 20, 2005

A weather observatory was successfully launched into orbit this morning to build upon a 45-year history of tracking the Earth's environmental conditions from space.

The 3,130-pound NOAA-N craft was hauled aloft by Boeing's Delta 2 rocket, which roared away from Vandenberg Air Force Base, California, at 1022 GMT (6:22 a.m. EDT; 3:22 a.m. PDT).

We have posted an extended length movie of today's launch that shows the final two minutes of the countdown through ignition of the rocket's second stage and jettison of the nose cone. The video is available to Spaceflight Now Plus subscribers.

The fifth launch try proved to be the charm for this $341 million mission. The first two tries were thwarted by high winds, electrical problems at the pad scrubbed the third countdown and a fourth opportunity was cancelled after a broken fuel vent hose prompted contamination checks of the satellite.

But this morning's countdown was quiet and smooth, leading to liftoff right at the opening of the day's launch window. Low clouds and fog blanketed the coastal launch site, ruining the view for night-owl spectators and reporters at the base. But those watching downrange were treated to a spectacular sight of the rocket streaking into the predawn sky with a setting moon as backdrop.

Sixty-five minutes later over Africa, the rocket's second stage separated from its cargo to complete the launch. Then the Lockheed Martin-built satellite deployed the power-generating solar array and began its life in space.

Controllers renamed the satellite NOAA-18, according to traditions, once it safely arrived in orbit. The craft will undergo several weeks of tests before entering service this summer to replace the aging NOAA-16 satellite.

The NOAA spacecraft circle the planet 14 times a day, collecting imagery, temperature measurements and atmospheric profiles for meteorologists to create weather forecasts.

"This information goes into the National Weather Service's forecast models. The output gets transmitted to the National Weather Service sites and private weather systems like The Weather Channel," said Mike Mignogno, program manager for the Polar Operational Environmental Satellites at NOAA. "It helps the local forecaster know what the chances of precipitation are, what the temperatures are going to be, what the winds are going to be over the next day.

"It is integral to the local forecast."

Polar-orbiting weather satellites have been used since the early days of the space program. The information allows scientists to monitor long-term climate change and Earth's environmental health.

This newest spacecraft becomes the catalyst to developing the Global Earth Observation System of Systems.

"GEOSS was established by an agreement signed by 60 nations just recently, including the United States and European Commission. (The program) commits to linking existing environmental monitoring technology into one system to better predict a whole host of issues to the benefit to mankind, including weather, climate and natural catastrophe," said Gregory Withee, assistant administrator for the NOAA Satellite and Information Service.

"The challenge before us is to connect with scientific dots and technology dots an integrated, international, comprehensive Global Earth Observation System of Systems so that we have a complete picture of the global environment. NOAA satellites, including NOAA-N, will play a significant role."

Like its predecessors, NOAA-N is fitted with the international Search and Rescue Satellite-Aided Tracking System, called COSPAS-SARSAT. Over the past 23 years, spacecraft equipped to hear distress signals from emergency beacons are credited with saving almost 5,000 people in the United States, and more than 18,000 worldwide.

In the first four months of 2005, NOAA said 36 people were rescued in the U.S. thanks to the vital link between the satellites and beacons carried by airplanes, boats and hikers. Last year, Alaska had the most rescues, with 37, while Florida had 36.

"These beacons help save lives," Withee said. "As temperatures get warmer, and outdoor activities increase in remote areas -- where cell phones don't work -- having one of these emergency beacons is a good safety practice."

"Beacons remain one of the most reliable means of signaling a distress to search and rescue personnel," said Lieutenant Commander Jay Dell from the Coast Guard's Office of Search and Rescue. "The timeliness and accuracy of SARSAT alerts are extremely valuable to search and rescue planning and response."

The weather satellites detect a beacon's transmission and alert ground controllers in Suitland, Maryland. From there, the signal is forwarded to a Rescue Coordination Center operated by the U.S. Coast Guard for maritime emergencies or the Air Force for land search and rescue situations, according to NOAA.

A final satellite in this current series is scheduled for launch in December 2007. The NOAA-N Prime spacecraft is being rebuilt at Lockheed Martin's manufacturing plant after being damaged two years ago in a freak accident. The satellite fell on its side while being moved because workers failed to realize it wasn't bolted to the handling cart.

1149 GMT (7:49 a.m. EDT)

"So far things look very good. The spacecraft is responding, the solar array has been deployed, we're now deploying some antennas. Everything seems to be lining up well," says NOAA-N program manager Martin Davis.

1147 GMT (7:47 a.m. EDT)

"The Delta performed nominally -- just a perfect flight today," NASA launch manager Omar Baez says. The rocket delivered the NOAA-N spacecraft into the right orbit, within a tenth of a nautical mile in apogee and perigee, he said.

1144 GMT (7:44 a.m. EDT)

"We have a good operating spacecraft so far," NOAA-N program manager Martin Davis reports. The solar array deployment was a success.

1140 GMT (7:40 a.m. EDT)

T+plus 78 minutes. Data being received in the satellite mission control center indicates that the deployments are happening. It will take a few minutes, however, to confirm all has gone according to plan. In about 8 minutes, the spacecraft will pass over its tracking facility in Fairbanks, Alaska.

1135 GMT (7:35 a.m. EDT)

We have posted a movie of today's launch. The video is available to Spaceflight Now Plus subscribers.

1132 GMT (7:32 a.m. EDT)

T+plus 70 minutes. The NOAA-N satellite's 20-foot-long, 9-foot-wide solar array should be unfurling at this time. This 10-panel array was folded up during launch, then extends accordion-style in orbit to generate power for the spacecraft.

Also upcoming in the next few minutes, three antennas and an instrument sunshade will be deployed. The antennas are used to receive data from ground weather transmitters, send the satellite's imagery to receivers on Earth and hear search and rescue beacons.

All of these critical deployments are accomplished via autonomous functions by the spacecraft itself.

1127 GMT (7:27 a.m. EDT)

T+plus 65 minutes, 44 seconds. SPACECRAFT SEPARATION! The NOAA-N spacecraft that will track weather patterns across the globe and monitor our planet's health has been released from the Boeing Delta 2 rocket's second stage, completing this morning's launch.

This marks the 117th successful Delta 2 rocket launch out of 119 flights since 1989 and extends the string of consecutive successes to 64 dating back to 1997.

The next Delta 2 launch is scheduled for mid-June from Cape Canaveral, Florida. The mission will carry the newest Global Positioning System military navigation satellite for the U.S. Air Force.

1125 GMT (7:25 a.m. EDT)

T+plus 63 minutes, 30 seconds. Deployment of NOAA-N from the second stage is expected in about two minutes.

1124 GMT (7:24 a.m. EDT)

T+plus 62 minutes, 30 seconds. The second stage is now maneuvering to the spacecraft separation orientation.

1124 GMT (7:24 a.m. EDT)

T+plus 62 minutes. The just-completed second stage burn was the normal duration and all appears to have gone as expected.

1122 GMT (7:22 a.m. EDT)

T+plus 60 minutes, 55 seconds. The rocket has successfully achieved a good orbit with an apogee of 466.7 miles, perigee of 463.2 miles and inclination of 98.73 degrees, Boeing reports.

1121 GMT (7:21 a.m. EDT)

T+plus 59 minutes, 39 seconds. SECO 2. Engine shutdown has occurred.

1121 GMT (7:21 a.m. EDT)

T+plus 59 minutes, 26 seconds. The second stage engine has ignited for a 13-second firing to propel the NOAA-N spacecraft into a circular polar orbit.

1120 GMT (7:20 a.m. EDT)

T+plus 58 minutes. The vehicle is in the engine restart position.

1119 GMT (7:19 a.m. EDT)

T+plus 57 minutes. The Malindi station has acquired the Delta rocket to track the upcoming engine firing and payload deployment.

1117 GMT (7:17 a.m. EDT)

T+plus 55 minutes. The second stage remains in a normal coast mode. Engine start is about four minutes away.

1115 GMT (7:15 a.m. EDT)

T+plus 53 minutes. The vehicle is nulling its BBQ rolling motion as planned.

1113 GMT (7:13 a.m. EDT)

T+plus 51 minutes. Data is being received via the Hartebeesthoek site.

1107 GMT (7:07 a.m. EDT)

T+plus 45 minutes. As the rocket coasts in this parking orbit, the second stage performs a "BBQ roll" maneuver to keep the thermal conditions on the vehicle equal. This maneuver was scheduled to start at T+plus 18 minutes, 30 seconds and conclude at T+plus 52 minutes, 40 seconds. Since the Delta 2 rocket is not within range of any data relay station, this could not be confirmed in real-time.

At T+plus 52 minutes, 50 seconds, the rocket is programmed to begin orienting itself into the proper position for engine ignition. This maneuver will take about four-and-a-half minutes to complete.

1102 GMT (7:02 a.m. EDT)

T+plus 40 minutes. The next firing by the Delta rocket's second stage is coming up in 19 minutes. The Hartebeesthoek tracking station in South Africa should acquire the rocket in about 10 minutes. That will be followed by the Malindi, Kenya ground site picking up the rocket's signal five minutes later. Malindi will provide live confirmation of the second stage burn and release of the NOAA-N satellite.

1055 GMT (6:55 a.m. EDT)

T+plus 33 minutes. NASA hasn't reported any problems during this morning's launch. The vehicle is quietly flying above the Earth, heading the point in space to reignite its second stage engine to propel NOAA-N into the desired circular polar orbit.

1040 GMT (6:40 a.m. EDT)

T+plus 18 minutes. The rocket is coasting until the second stage restarts its engine at T+plus 59 minutes, 21 seconds for a brief firing to circularize the orbit. Deployment of NOAA-N from the launch vehicle is expected 65 minutes after liftoff.

1037 GMT (6:37 a.m. EDT)

T+plus 15 minutes. The rocket is passing out of range from the tracking vessel. This creates a data blackout until the vehicle soars above ground stations in Africa about 40 minutes from now.

1033 GMT (6:33 a.m. EDT)

T+plus 11 minutes, 24 seconds. SECO 1. The second stage engine has shut down to complete the first of two firings to deliver NOAA-N into the proper polar orbit today.

1032 GMT (6:32 a.m. EDT)

T+plus 10 minutes, 25 seconds. A track ship in the Pacific has acquired the rocket's telemetry signal as the Delta flies beyond Vandenberg's horizon.

1031 GMT (6:31 a.m. EDT)

T+plus 9 minutes, 15 seconds. About two minutes remain in this burn of the second stage engine to achieve the intended parking orbit.

1030 GMT (6:30 a.m. EDT)

T+plus 8 minutes. The official liftoff time was 1022:01.566 GMT.

1029 GMT (6:29 a.m. EDT)

T+plus 7 minutes, 25 seconds. The Delta 2 rocket is 100 miles in altitude, 560 miles downrange from the launch pad, traveling at 11,700 mph.

1028 GMT (6:28 a.m. EDT)

T+plus 6 minutes, 20 seconds. Second stage engine performance reported normal as the vehicle speeds along at over 10,000 mph.

1027 GMT (6:27 a.m. EDT)

T+plus 5 minutes, 30 seconds. It was a good clean separation of the nose cone. Meanwhile, the second stage is firing normally.

1027 GMT (6:27 a.m. EDT)

T+plus 5 minutes, 2 seconds. The rocket's nose cone enclosing the NOAA-N satellite has been jettisoned. It is no longer needed to protect the spacecraft.

1026 GMT (6:26 a.m. EDT)

T+plus 4 minutes, 44 seconds. The Delta's second stage engine has ignited!

1026 GMT (6:26 a.m. EDT)

T+plus 4 minutes, 36 seconds. MECO. The first stage main engine cutoff is confirmed, and the spent stage has been jettisoned!

1025 GMT (6:25 a.m. EDT)

T+plus 3 minutes, 55 seconds. The Delta 2 rocket is 40 miles in altitude, 75 miles downrange, traveling at 6,400 mph.

1025 GMT (6:25 a.m. EDT)

T+plus 3 minutes. The first stage main engine continues to burn. The vehicle is 27 miles in altitude, 21 miles downrange from the launch pad and traveling at 3,300 mph.

1024 GMT (6:24 a.m. EDT)

T+plus 2 minutes. The Delta 2 rocket is 16 miles in altitude, 9 miles downrange from the launch pad and traveling at 1,200 mph.

1023 GMT (6:23 a.m. EDT)

T+plus 1 minute, 45 seconds. The ground-lit boosters have jettisoned from the first stage. They remained attached until the rocket cleared off-shore oil rigs.

1023 GMT (6:23 a.m. EDT)

T+plus 1 minute, 10 seconds. All three ground-start solid rocket boosters have burned out, leaving Delta 2's first stage RS-27A main engine to provide the thrust on the continued journey to space.

1022 GMT (6:22 a.m. EDT)

T+plus 55 seconds. The rocket has climbed through the area of maximum aerodynamic pressure.

1022 GMT (6:22 a.m. EDT)

T+plus 30 seconds. Nearing Mach 1.

1022 GMT (6:22 a.m. EDT)

T+plus 15 seconds. The vehicle is arcing to its southerly heading for the flight away from Vandenberg Air Force Base.

1022 GMT (6:22 a.m. EDT)

LIFTOFF! Liftoff of the Boeing Delta 2 rocket launching the NOAA-N weather observatory to build upon a 45-year history of tracking the Earth's environmental conditions from space.

1021 GMT (6:21 a.m. EDT)

T-minus 30 seconds.

The launch ignition sequence will begin at T-minus 2 seconds when a Boeing engineer triggers the engine start switch. The process begins with ignition of the two vernier engines and first stage main engine start. The three ground-lit solid rocket motors then light at T-0 for liftoff.

1021 GMT (6:21 a.m. EDT)

T-minus 1 minute. The Range has given its final clear-to-launch.

The Delta 2 rocket's second stage hydraulic pump has gone to internal power after its pressures were verified acceptable.

1020 GMT (6:20 a.m. EDT)

T-minus 80 seconds. LOX topping to 100 percent is underway.

1020 GMT (6:20 a.m. EDT)

T-minus 1 minute, 45 seconds. The launch pad water suppression system is being activated.

1020 GMT (6:20 a.m. EDT)

T-minus 2 minutes. The first stage liquid oxygen vents are now being closed so the LOX tank can be pressurized for launch. Puffs of vapor from a relief valve on the rocket will be seen in the remainder of the countdown as the tank pressure stabilizes.

1019 GMT (6:19 a.m. EDT)

T-minus 2 minutes, 30 seconds. The NOAA-N satellite has been declared "go" for launch.

1019 GMT (6:19 a.m. EDT)

T-minus 2 minutes, 45 seconds. Vehicle ordnance is being armed.

1019 GMT (6:19 a.m. EDT)

T-minus 3 minutes. All elements remain ready for liftoff.

1018 GMT (6:18 a.m. EDT)

T-minus 3 minutes, 45 seconds and counting. The Delta 2 rocket's systems are now transferring to internal power for launch. And the launch pad water system is being enabled.

1018 GMT (6:18 a.m. EDT)

T-minus 4 minutes and counting! Clocks are ticking down the final moments for liftoff of Delta 312 and the NOAA-N weather satellite. Launch is set for 1022:01 from Vandenberg Air Force Base, California.

1017 GMT (6:17 a.m. EDT)

The "go" has been given to restart the countdown clock in one minute.

1016 GMT (6:16 a.m. EDT)

Just two minutes are remaining before the countdown resumes.

1014 GMT (6:14 a.m. EDT)

The team members are now receiving final instructions on countdown procedures.

1014 GMT (6:14 a.m. EDT)

The launch team readiness poll just occurred. There were no constraints announced. Liftoff is still "go" for 1022 GMT.

1012 GMT (6:12 a.m. EDT)

"The NASA team is ready to enter Terminal Count," launch manager Omar Baez reported after completing a poll of his crew.

1011 GMT (6:11 a.m. EDT)

NOAA-N has successfully transitioned to internal battery power for launch.

1010 GMT (6:10 a.m. EDT)

Now 12 minutes from launch. All systems remain "go."

1008 GMT (6:08 a.m. EDT)

The NOAA-N spacecraft is undergoing its final re-configuration for launch.

1008 GMT (6:08 a.m. EDT)

T-minus 4 minutes and holding. The countdown has entered the final planned hold point for today's launch. During this planned 10-minute hold, final polls will be conducted to ensure everything is set for liftoff.

1006 GMT (6:06 a.m. EDT)

The launch weather officer has announced that all conditions are within limits for flight.

1003 GMT (6:03 a.m. EDT)

The first stage kerosene fuel tank is being pressurized for launch.

1002 GMT (6:02 a.m. EDT)

T-minus 10 minutes.

0958 GMT (5:58 a.m. EDT)

Inhibited checks are now beginning for the Range Safety command destruct receivers that would be used in destroying the Delta rocket should the vehicle veer off course or malfunction during the launch.

0952 GMT (5:52 a.m. EDT)

T-minus 20 minutes and counting. Clocks are ticking again after the planned 20-minute hold. The countdown will proceed to T-minus 4 minutes where the final hold is scheduled.

0948 GMT (5:48 a.m. EDT)

The Boeing launch team was just polled to confirm everyone is "ready" to continue the countdown. The NASA management team voiced its readiness a few minutes ago.

0942 GMT (5:42 a.m. EDT)

Now half-way through this built-in hold at T-minus 20 minutes. Once the countdown resumes, clocks will tick down to the T-minus 4 minute mark where a 10-minute hold is planned.

0940 GMT (5:40 a.m. EDT)

There are no technical issues being addressed with the Delta 2 rocket, NOAA-N spacecraft, Range assets or ground support equipment, and the weather is acceptable for liftoff at 1022 GMT this morning.

0939 GMT (5:39 a.m. EDT)

Data link checks have been completed.

0932 GMT (5:32 a.m. EDT)

T-minus 20 minutes and holding. A 20-minute built-in hold in the countdown has started. These holds are designed to give the launch team a chance to work any problems or catch up on activities that might be running behind schedule. Engineers will also have time to examine all the data from the just-completed steering tests.

Launch remains targeted for the precise moment of 1022:01 GMT from Vandenberg Air Force Base, California.

0928 GMT (5:28 a.m. EDT)

The first stage engine steering checks are complete.

0927 GMT (5:27 a.m. EDT)

T-minus 25 minutes and counting. The countdown is nearing a planned 20-minute built-in hold at the T-minus 20 minute mark. Another hold is scheduled at T-minus 4 minutes. Launch is still set to occur at 1022 GMT this morning.

0925 GMT (5:25 a.m. EDT)

The second stage engine slews are complete. First stage tests have begun.

0922 GMT (5:22 a.m. EDT)

With one hour remaining in the countdown to liftoff, the launch team is beginning the "slew" or steering checks of the first and second stage engines. These are gimbal tests of the nozzles on the first stage main engine and twin vernier engines and second stage engine to ensure the rocket will be able to steer itself during launch.

0912 GMT (5:12 a.m. EDT)

Next up in the countdown will be engine steering checks starting about 10 minutes from now.

0903 GMT (5:03 a.m. EDT)

Loading of the Delta 2 rocket's first stage liquid oxygen tank was completed at 0902:45 GMT. The operation took 24 minutes and 13 seconds today. The tank will be replenished through the countdown to replace the super-cold liquid oxygen that naturally boils away.

The rocket is now fully fueled for launch. The vehicle's first stage was successfully loaded with RP-1 kerosene fuel along with the liquid oxygen today. The second stage was filled with its storable nitrogen tetroxide and Aerozine 50 fuels two weeks. The three strap-on booster rockets are solid-propellant.

0858 GMT (4:58 a.m. EDT)

Now 20 minutes into the liquid oxygen loading. Once the first stage tank is 95 percent full, the "rapid load" valve will be closed and the slower "fine load" phase will continue to fill the rocket.

0852 GMT (4:52 a.m. EDT)

The countdown is entering the final 90 minutes to liftoff. All continues to go well today.

0848 GMT (4:48 a.m. EDT)

The outer skin of the first stage is icing over as the liquid oxygen tanking operating passes the 10-minute point. It will take about 25 minutes to fill the rocket.

0838 GMT (4:38 a.m. EDT)

Super-cold liquid oxygen is starting to flow into the first stage of the Boeing Delta 2 rocket as the countdown continues for today's 1022 GMT launch.

The liquid oxygen, chilled to Minus-298 degrees F, is being pumped from a launch pad storage tank, through plumbing and into the bottom of the rocket. The LOX and the RP-1 kerosene fuel -- loaded aboard the vehicle a few hours ago -- will be consumed by the first stage main engine.

0833 GMT (4:33 a.m. EDT)

The launch team has been given a "go" to start the preparations for loading the rocket's first stage liquid oxygen tank.

0833 GMT (4:33 a.m. EDT)

Roadblocks around the pad are established and the flight hazard area is cleared of all personnel, safety officials report. These steps are confirmed before the hazardous operation of liquid oyxgen loading starts.

0825 GMT (4:25 a.m. EDT)

NASA Launch Manager Omar Baez has polled the space agency's advisory team for a "go" to start loading liquid oxygen. No problems were reported.

Next, Boeing Mission Director Rich Murphy will do his readiness check before giving the final approval to the launch team.

0822 GMT (4:22 a.m. EDT)

The Boeing Delta 2 rocket launch of the NOAA-N spacecraft to track global weather patterns is just two hours away now.

0819 GMT (4:19 a.m. EDT)

Launch Weather Officer Capt. Paul Lucyk reports all conditions are fine for liftoff this morning.

0815 GMT (4:15 a.m. EDT)

Second stage propellant tank pressurization has been completed. The stage is loaded with storable hypergolic propellants.

0812 GMT (4:12 a.m. EDT)

The TDRS spacecraft in NASA's constellation of Tracking and Data Relay Satellites is confirmed ready to support this morning's launch. TDRS will begin receiving telemetry from the NOAA-N satellite once the rocket's nose cone is shed about five minutes after liftoff and continue through the 65-minute ascent.

0807 GMT (4:07 a.m. EDT)

Coming up in about 10 minutes, the management team will receive a weather briefing before having to make the "go/no go" decision for pumping liquid oxygen into the Delta 2 rocket's first stage. That loading operation is scheduled to start around 0837 GMT,

0800 GMT (4:00 a.m. EDT)

The launch team is not working any technical issues, the weather is acceptable and the countdown is progressing smoothly for an on-time liftoff today.

0746 GMT (3:46 a.m. EDT)

The first stage helium and nitrogen system pressurization has been completed.

0726 GMT (3:26 a.m. EDT)

Activation of the rocket's guidance control system is starting.

0725 GMT (3:25 a.m. EDT)

Winds at the pad are just 9 knots from the north. Visibility has improved at the pad, as the moon can be seen overhead. Incredibly foggy conditions made the launch complex nearly invisible a couple of hours ago.

0722 GMT (3:22 a.m. EDT)

T-minus 150 minutes and counting! The Terminal Countdown is now underway for this fifth attempt to launch the Delta 2 rocket and the NOAA-N weather satellite. Blastoff from the SLC-2W pad at Vandenberg Air Force Base, California, is still targeted for 1022:01 GMT.

The pad area has been cleared of workers. However, a warning horn is being sounded at the complex as a precaution to alert any remaining personnel in the vicinity that they should leave immediately.

The pad clearing will allow the start of hazardous operations such as the pressurization of helium and nitrogen storage tanks inside the rocket's first and second stages, along with the second stage fuel and oxidizer tanks.

The countdown currently stands at T-minus 150 minutes. However, there are a pair of holds -- totaling 30 minutes in duration -- planned at T-minus 20 minutes and T-minus 4 minutes.

0714 GMT (3:14 a.m. EDT)

Each launch team member has been polled to voice a "ready" status to begin Terminal Count.

0707 GMT (3:07 a.m. EDT)

"Man stations for Terminal Count." The launch team members have been instructed to take positions at their consoles. A readiness poll will be performed in a few minutes to verify everyone is prepared to resume the countdown at the end of this scheduled hold at 0722:01 GMT.

0634 GMT (2:34 a.m. EDT)

Technicians at the launch pad pump house report the three water deluge pumps have been successfully powered up. Electrical trouble with these dumps was at the heart of last Friday's launch scrub.

0622 GMT (2:22 a.m. EDT)

T-minus 150 minutes and holding. The countdown has entered a planned 60-minute built-in hold. Clocks will be stopped two more times this morning -- at T-minus 20 minutes and T-minus 4 minutes -- leading to liftoff at 1022 GMT.

0522 GMT (1:22 a.m. EDT)

With five hours remaining in the count, crews are busy at the Space Launch Complex-2 West pad removing work platforms around the bottom of the rocket and securing equipment at the facility.

The full launch team and senior management group will be arriving at their consoles over the next 90 minutes. The Terminal Countdown begins two hours from now.

0405 GMT (12:05 a.m. EDT)

Countdown activities are progressing for liftoff just over six hours from now. The mobile service tower is retracted to its launch spot, revealing the Delta 2 rocket. But Vandenberg has been blanketed by dense fog tonight, significantly hampering visibility at the launch site.

THURSDAY, MAY 19, 2005

At the 2130 GMT weather briefing, Air Force meteorologists indicated that winds should be acceptable for rollback of the mobile service tower at the Delta 2 rocket launch pad later tonight.

"The final launch readiness preparations are underway," NASA spokesman George Diller said from Vandenberg Air Force Base. "There are no issues or concerns."

Loading of 10,000 gallons of RP-1 kerosene propellant into the vehicle's first stage is scheduled to commence at 0000 GMT. The fueling will occur several hours earlier than usual as a means of adding extra weight to the rocket before the gantry is wheeled back to expose the Delta to the winds.

Tower retraction is expected to start around 0200 GMT.

The weather forecast for the 1022 GMT liftoff time remains favorable.

This will be the fifth attempt to launch the Delta rocket and NOAA-N weather observatory from California's Central Coast. The first two tries were thwarted by high winds, electrical problems at the pad scrubbed the third countdown and a fourth opportunity was cancelled after a broken fuel vent hose prompted contamination checks of the satellite.

Watch this page for live play-by-play reports of the final countdown and launch.

1640 GMT (12:40 p.m. EDT)

Much like the first two launch attempts for this mission, officials are nervously watching ground winds that could be blowing near the acceptable limit for retracting the mobile service tower from around the Delta 2 rocket later today. The forecast improves overnight for the scheduled liftoff time. See the latest detailed outlook here.

WEDNESDAY, MAY 18, 2005

The final Launch Readiness Review was held at Vandenberg late today and culminated with the "go" to proceed into the countdown on Thursday.

"There are no remaining issues or concerns," NASA spokesman George Diller said.

Liftoff remains scheduled for Friday morning at 1022 GMT (6:22 a.m. EDT; 3:22 a.m. PDT).

Technicians plan to load RP-1, a highly refined kerosene fuel, into the rocket's first stage around 0000 GMT (8 p.m. EDT; 5 p.m. PDT) Thursday evening. Retraction of the mobile service tower is scheduled to occur about two hours later, if winds allow.

The gusty winds are forecast to be near the limit for tower rollback, Diller said.

TUESDAY, MAY 17, 2005

Following extensive inspections after a broken fuel venting hose generated concerns, a civilian weather-monitoring satellite and the rocket that will ferry the observatory into space are free of contamination, engineers concluded Tuesday. Read our full story.

1630 GMT (12:30 p.m. EDT)

The weather forecast for launch opportunities on Friday and Saturday predicts a return of gusty winds at Vandenberg. Strong winds scrubbed the first two launch attempts of this mission. You can read the forecast in detail here.

Read our earlier status center coverage.