Not knowing if the future will bring it more launch business, the workhorse Delta 2 rocket successfully deployed a vital climate and weather observatory this morning before riding into an uncertain state of limbo.

Read our full story.

See our launch pad photos.

"ULA is proud to have served NASA with 50 Delta 2 launches, achieving 100 percent mission success for a very diverse array of exceptionally important science missions. "Today's successful NPP launch is a critical first step in demonstrating our country's next-generation earth-observing satellite system. NPP will monitor weather conditions and gather climate data to greatly improve our knowledge of Earth's systems," said Jim Sponnick, ULA vice president, Mission Operations.

"In addition to the NPP spacecraft, the Delta 2 also carried three Poly Picosatellite Orbital Deployers (P-POD) dispensers on the upper stage that deployed six cubesats following completion of the primary NPP mission," said Sponnick. "We are pleased that ULA can provide access to space for these university research satellites and expand the reach of the science community."

This is the 96th consecutive successful Delta 2 rocket launch dating back to May 1997. The Delta 2's overall history since debuting in 1989 has achieved 149 successes in 151 flights.

There's no additional Delta 2 rocket launches currently scheduled. But ULA has five more vehicles available that the company hopes to sell in the future.

T+plus 101 minutes, 47 seconds. P-POD 3 DEPLOY! A pair of DICE satellites has been released from the Delta 2 rocket, officially completing this launch!

The Dynamic Ionosphere CubeSat Experiment will obtain electric field and electron density measurements for space weather research. The mission partners include Utah State, Clemson, Embry-Riddle Aeronautical University and the Atmospheric and Space Technology Research Associates.

T+plus 100 minutes, 9 seconds. P-POD 2 DEPLOY! RAX 2 has separated from the launcher.

The Radio Aurora Explorer 2, also from the University of Michigan, will study the microphysics that lead to plasma conditions that disrupt satellite communications.

T+plus 98 minutes, 45 seconds. P-POD 1 DEPLOY! AubieSat 1, Explorer 1 (Prime) and M-Cubed have ejected from their dispenser on the Delta 2 rocket.

AubieSat 1 was made by Auburn University undergraduate students to study radio wave propagation through the ionosphere and test protective films for solar panels.

Explorer 1 (Prime) Unit 2 from Montana State University also plans to probe space weather by monitoring trapped electrons in the horns of the radiation belts. It is named for America's first satellite in space.

M-Cubed -- the Michigan Multipurpose Minisat -- comes from the University of Michigan to image the Earth and demonstrate the craft's design for use by future projects.

T+plus 97 minutes. The Poly Picosatellite Orbital Deployer (P-POD) is built just up the road from the Vandenberg Air Force Base launch site by California Polytechnic State University in San Luis Obispo.

T+plus 95 minutes. Besides hauling the NPP environmental observatory to orbit this morning, a half-dozen student-made hitchhikers are launching aboard the Delta 2 rocket from California.

After releasing the primary payload and maneuvering into a different orbit, the rocket will issue commands to eject the minuscule CubeSats from their P-POD carriers affixed to the second stage booster.

AubieSat 1, DICE, Explorer 1 (Prime) Unit 2, M-Cubed and RAX 2 are their names. Together, they are getting to ride the NASA-funded rocket as part of the space agency's second Educational Launch of Nanosatellite, or ELaNa, project.

T+plus 94 minutes, 15 seconds. The second stage has successfully completed the burn designed to move out of the orbital plane of NPP. This is known as the evasive burn, and puts the rocket into an elliptical orbit.

T+plus 83 minutes. NPP is power positive, confirming its solar array and associated systems are functioning properly.

T+plus 68 minutes. "The flight went terrific," said Tim Dunn, NASA launch director. "We've just confirmed spacecraft separation -- a lot of celebration in the control room right now -- but overall a great performance of the rocket. We'll do quick look in an hour but from what we saw on the consoles, everything looked very nominal."

T+plus 66 minutes, 50 seconds. The power-generating solar array on the NPP spacecraft has been unfurled as the satellite begins its life in orbit.

T+plus 59 minutes, 10 seconds. SPACECRAFT SEPARATION! NPP spacecraft has been released from the Delta 2 rocket's second stage, completing the primary objective of today's launch!

Coming up in about 40 minutes, the rocket will eject a six small CubeSat secondary payloads.

T+plus 58 minutes, 30 seconds. Roll, pitch and yaw rates are nulling out.

T+plus 56 minutes. The orbits achieved by both burns of the second stage have been right on the mark.

T+plus 54 minutes. The rocket is repositioning itself to the proper orientation for release of NPP.

T+plus 52 minutes, 33 seconds. SECO 2. The orbit adjustment burn occurred as planned just south of Madagascar.

T+plus 52 minutes, 11 seconds. The second stage engine has ignited for the 22-second firing to propel its 2.5-ton spacecraft payload into the proper polar orbit.

T+plus 51 minutes. The second stage is completing its maneuver into the proper orientation for the upcoming engine firing.

T+plus 50 minutes, 15 seconds. Delta is 434 miles in altitude and over 10,055 miles downrange from the launch pad.

T+plus 42 minutes. The next firing by the Delta rocket's second stage is coming up in 10 minutes while flying on the other side of the world from Vandenberg. The orbiting Tracking and Data Relay Satellite System will continue receiving the rocket's telemetry for transmission back to the launch site, providing the confirmation of the second stage burn and release of the NPP satellite.

Check out these incredible long-exposure images of the Delta 2 rocket streaking to space!

See our photo gallery.

T+plus 35 minutes. The rocket is crossing Antarctica now as it flies in a polar orbit around Earth. A map of the rocket's planned flight path is available here.

T+plus 30 minutes. The rocket is coasting until the second stage restarts its engine at T+plus 52 minutes, 5 seconds for a brief 22-second firing to put the vehicle into a near-circular orbit above Earth. Deployment of NPP from the launch vehicle is expected almost 59 minutes after liftoff.

T+plus 24 minutes. As the rocket coasts in this parking orbit, it performs a "BBQ roll" maneuver to keep the thermal conditions on the vehicle equal.

T+plus 20 minutes. Live telemetry continues to be received via NASA's Tracking and Data Relay Satellite System. Today's launch is the fifth Delta 2 flight to use TDRS during the long mission instead of ordering support from mobile telemetry assets and faraway ground sites after the rocket passes out of view from Vandenberg.

T+plus 16 minutes, 45 seconds. Delta is 115.5 miles in altitude, 2,883 miles downrange from the launch pad and traveling at 17,011 mph.

T+plus 11 minutes, 10 seconds. The Delta 2 rocket is 100 miles in altitude, 1,533 miles south from the launch pad with a velocity of 17,009 mph.

T+plus 10 minutes, 37 seconds. SECO 1 has been confirmed. The second stage's Aerojet-made engine completed its initial burn for the launch. Delta and NPP have reached orbit.

T+plus 10 minutes, 20 seconds. Delta is 103 miles in altitude, 1321 miles downrange from the launch pad and traveling at 16,700 mph.

T+plus 9 minutes, 45 seconds. The second stage continues to fire normally.

T+plus 9 minutes, 15 seconds. The rocket is about 101.5 miles up, 1,118 miles downrange, traveling at at 15,524 mph.

T+plus 8 minutes, 30 seconds. About two minutes remain in this burn of the second stage engine to achieve the intended parking orbit.

T+plus 8 minutes, 25 seconds. Speed now 14,669 mph.

T+plus 7 minutes, 40 seconds. Rock solid chamber pressure on the second stage.

T+plus 7 minutes, 20 seconds. Delta is 96 miles up, 735 miles downrange traveling at 13,714 mph.

T+plus 6 minutes, 15 seconds. The vehicle is 91 miles in altitude, 516 miles downrange from the launch pad and traveling at 12,820 mph. The first stage main engine continues to burn normally.

T+plus 5 minutes, 25 seconds. Second stage looking good as this initial burn up gets underway.

T+plus 4 minutes, 49 seconds. The rocket's nose cone enclosing the satellite payload has been jettisoned.

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

T+plus 4 minutes, 39 seconds. MECO. The first stage main engine cutoff is confirmed, and the spent stage has been jettisoned.

T+plus 4 minutes, 15 seconds. The vehicle is 57 miles in altitude, 179 miles downrange from the launch pad and traveling at 10,092 mph. The first stage main engine continues to burn normally.

T+plus 3 minutes, 9 seconds. The Delta 2 rocket is 42 miles in altitude, 72 miles downrange and traveling at 5,700 mph.

T+plus 3 minutes. The first stage main engine still firing well. The Pratt & Whitney Rocketdyne powerplant consumes kerosene fuel and liquid oxygen to produce about 200,000 pounds of thrust.

T+plus 2 minutes, 55 seconds. Delta now traveling at Mach 10.

T+plus 2 minutes, 20 seconds. The trio of ATK-made solid rocket boosters ignited inflight have burned out of propellant and separated. The Delta 2's first stage RS-27A main engine will be providing the sole thrust for the next few minutes.

T+plus 2 minutes. Delta is traveling at Mach 5.

T+plus 1 minute, 35 seconds. The ground-lit boosters have jettisoned from the first stage. They remained attached until the rocket cleared off-shore oil rigs.

T+plus 1 minute, 12 seconds. All six ground-start solid rocket boosters have burned out and the three air-lit motors were just lit.

T+plus 50 seconds. The rocket has flown through the area of maximum aerodynamic pressure in the lower atmosphere. Coming up on ignition of the remaining three strap-on boosters.

T+plus 35 seconds. Delta has broken the sound barrier, rapidly accelerating on the power of its first stage main engine and the six ground-lit strap-on solid-fuel boosters.

T+plus 15 seconds. The launch vehicle is departing Vandenberg Air Force Base, heading south for the trek downrange over the Pacific carrying the NPP spacecraft.

LIFTOFF! Liftoff of the Delta 2 with NPP -- the world's next-generation weather watcher heads to space as the industry workhorse rocket rides one more time!

T-minus 30 seconds. SRB ignitors will be armed at T-minus 11 seconds.

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

T-minus 1 minute. All remains "go" for launch.

T-minus 80 seconds. First stage liquid oxygen topping to 100 percent is underway.

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

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.

T-minus 2 minutes, 30 seconds. The NPP payload has been declared "go" for launch.

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

T-minus 3 minutes and counting down to the Delta rocket launch dedicated to deploying the NPP spacecraft to bridge the Earth observing satellites of yesterday to the next-generation of tomorrow.

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.

T-minus 4 minutes and counting! Clocks are ticking down the final moments for liftoff of Delta 357 with the NPP spacecraft. Launch is set for 2:48:01 a.m. local time from California's Central Coast.

Now five minutes from launch! The "go" has been given for release of the hold in one minute.

The NPP spacecraft has undergone final configuring for launch.

All systems are "go" for on-time launch today!

The launch team is being polled for the final time before liftoff to confirm systems are ready for the Delta 2 rocket and NPP spacecraft.

Now 10 minutes to go. The rocket's launch opportunity today is 9 minutes and 10 seconds long beginning at exactly 2:48:01 a.m. local (5:48:01 a.m. EDT; 0948:01 GMT). The window is dictated by the NPP satellite mounted atop the 12-story booster, and launching at the time ensures optimum insertion of the payload into the desired orbit from the Vandenberg Air Force Base pad.

NASA launch director Tim Dunn has polled his advisory team and the space agency is "go" to continue with the countdown.

That next weather balloon data is "green" for launch!

The next weather balloon data is expected in the next few minutes with wind speed and direction information on conditions aloft that the Delta 2 rocket must safely traverse.

T-minus 4 minutes and holding. The countdown has entered the final planned built-in hold. This is a scheduled 10-minute pause leading to today's liftoff time of 2:48:01 a.m. local (5:48:01 a.m. EDT; 0948:01 GMT) for the Delta 2 rocket.

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

The upper level wind conditions have been reported out of limits by the latest weather balloon. The team is awaiting the next data in a few minutes.

Twenty minutes from launch. The NPP satellite will become the 227th primary payload put into space by the venerable Delta 2 rocket over the past 22 years. Here's a look at some other stats about today's mission. This will be:

• The 357th Delta rocket launch since 1960
• The 233rd Delta launch with NASA involvement
• The 6th Delta of 2011
• The 151st Delta 2 rocket mission since 1989
• The 50th Delta 2 mission overseen by NASA
• The 41st Delta 2 rocket launch from Vandenberg AFB

T-minus 15 minutes and counting. Countdown clocks are running again following the planned 20-minute hold. The count will continue to the T-minus 4 minute mark where another hold is scheduled. Launch remains set to occur at precisely 2:48:01 a.m. local (5:48:01 a.m. EDT; 0948:01 GMT).

A poll of the launch team confirms everyone is ready to press ahead with the countdown after this pre-planned 20-minute hold.

Now just 40 minutes away from blastoff. The Delta rocket will be flying in its configuration known as the 7920-10 vehicle. The two-stage launcher is fitted with 9 strap-on solid-propellant motors and a 10-foot diameter composite nose cone.

Flying away from its coastal pad, the rocket will head southward over the Pacific Ocean. Six of the solid boosters are ignited on the ground, the other three light a minute into flight to give the Delta's first stage added thrust through the initial ascent. Once the solids burn out and separate, the kerosene-powered main engine will continue pushing the rocket to an altitude of 65 nautical miles.

The hydrazine-fueled then second stage ignites for a six-minute burn to achieve a preliminary parking orbit of 460 by 100 nautical miles some 10 minutes, 24 seconds into flight.

The rocket then settles into a quiet coast along a trajectory the cruises above the South Pacific before crossing Antarctica and proceeding northbound toward Africa.

The second stage reignites its engine for 22 seconds at T+plus 52 minutes off the southern coast of Madagascar to reach a near-circular polar orbit of 445.7 by 438.8 nautical miles inclined 98.705 degrees above the planet.

The NPP spacecraft is expected to be released from the rocket 58 minutes, 45 seconds after blastoff, or 3:46 a.m. local time back at Vandenberg.

Deployment of the half-dozen educational CubeSats will follow in intervals between 4:26 and 4:29 a.m.

T-minus 15 minutes and holding. Clocks have entered the first of two planned hold periods during the final portion of the Terminal Countdown. This pause will last 20 minutes in duration.

These holds are designed to give the launch team a chance to deal with any problems and catch up on work that could be running behind schedule.

Now moving into data link checks to verify good telemetry connections.

The first stage engine steering checks are complete.

The second stage engine slews just finished. First stage tests are starting.

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.

Sixty minutes to launch of the NPP observatory. Here's some thoughts about the spacecraft from Jack Hayes, director of the National Weather Service:

"As end users the global data we will receive from this advanced satellite, we at the National Weather Service are really excited in anticipation of getting it into operations as quickly as we can.

"NPP brings the promise of superior short-term and long-term weather and climate forecast, which inform daily activities of everyone -- from decision makers who protect the nation's safety and economic security to industries that power the nation's economic engine.

"The timing of this advanced satellite couldn't be better. National disasters are on the rise in the United States and this has been a devastating year...Long-standing records have been shattered for tornados, floods, blizzards, wildfires, drought and heatwaves. And now the sun is waking up as we head into a period of solar maximum.

"While NOAA forecasters do a great job alerting the nation to these major weather threats, we'll do an even better job with improved global data from NPP instruments updating our models."

Checks of the rocket's safety system have been accomplished in the past few minutes of the countdown.

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Loading of the Delta 2 rocket's first stage liquid oxygen tank has been accomplished. The process took 25 minutes and 50 seconds today. The tank will be replenished through the countdown to replace the super-cold liquid oxygen that naturally boils away.

And now the Delta 2 rocket stands fully fueled its launch of the NPP spacecraft at 2:48 a.m. local (5:48 a.m. EDT; 0948 GMT). The vehicle's first stage was successfully loaded with RP-1 kerosene fuel earlier today. The second stage was filled with its storable nitrogen tetroxide and Aerozine 50 fuels on Monday and Tuesday. And the nine strap-on booster rockets are solid-propellant.

The first stage liquid oxygen tank has reached the 95 percent full level. The "rapid load" valve was closed, with the slower "fine load" phase continuing to fill the tank.

Liftoff is just 90 minutes away. Everything is going smoothly for today's launch of the Delta 2 rocket with NPP. For meteorologists, they are looking forward to the enhanced data from the spacecraft to improve the quality of forecasting the weather.

Sophisticated numerical models run on the world's fastest computers ingest over a billion observations per day to generate daily weather forecasts. Louis Uccellini, director of NOAA's National Centers for Environmental Prediction explains:

"The backbone of that global observing system is the polar satellite data that both NASA and NOAA have worked on for decades to improve the operational forecast systems. So the launch of the NPP is a big deal for America.

"NPP does represent a bridge from the current polar satellite systems to the future operational platforms known as the Joint Polar Satellite System, or JPSS.

"Now the timing of this NPP launch could hardly be more appropriate -- 2011 has been termed 'the year of the billion dollar weather disasters.' We've already had 10 separate weather events, each inflicting at least $1 billion in damages including tornado outbreaks, fires, hurricanes that have affected the East Coast of the United States and we've had floods that have affected a large portion of the north-central and central part of the United States.

"With NPP's advanced microwave, infrared and visible data feeding NOAA's operational weather prediction models, we expect to improve our forecast skills and extend those forecast skills out to five-to-seven days in advance for hurricanes, several weather outbreaks and other extreme weather events.

"We expect these advanced instruments on NPP and high-resolution imager on this spacecraft to become a foundation for the global observing system that will be absolutely essential for NOAA's prediction models, especially for extreme events such as the recent occurrence of Hurricane Irene along the east coast of the United States.

"Beyond the weather forecasting, NOAA will use NPP data to track ash plumes from volcanic eruptions to enhance aviation safety, monitor crops, vegetation, the potential for drought and fires, measure variation in the Arctic sea ice and detect harmful algae blooms and other hazards that might endanger fisheries in fragile ocean ecosystems.

"NOAA is really looking forward to a successful launch. I am excited for the potential for NPP and its use in the operational numerical weather prediction models."

Ten minutes into the flow. LOX loading is an approximate 25-minute process to fill the first stage liquid oxygen tank.

Cryogenic liquid oxygen, chilled to Minus-298 degrees F, has started flowing from a 28,000-gallon storage tank at Space Launch Complex 2, through plumbing and into the bottom of the Delta 2 rocket. The LOX will be consumed by the first stage main engine during the first four-and-a-half minutes of flight along with the 10,000 gallons of RP-1 kerosene already loaded aboard the vehicle.

The launch team is performing the preparatory steps for filling the liquid oxygen tank.

The official "go" has been given to start first stage liquid oxygen loading right on time this morning.

NASA launch director Tim Dunn has completed a poll to confirm the agency management team is "go" for liquid oxygen loading. No technical problems are being reported in the countdown.

The rocket's guidance and control system has been brought online.

The weather outlook continues to be perfect for launch. The forecast calls for just a few high cirrus clouds at 25,000 feet, unrestricted visibility, no fog, easterly winds 8 to 12 knots and a temperature around 49 degrees F.

Just over two hours from launch.

The NPP spacecraft, its instruments, ground systems and rocket are priced at $1.5 billion. Jack Hayes, director of the National Weather Service, says the cost is worth the advancements that the satellite will bring:

"The nation isn't always aware of the benefits of taxpayer investment into big projects like NPP. But with more sophisticated Earth observing sensors aboard NPP, the National Weather Service will be able to demonstrate this value by saving even more lives and reducing economic losses with more-accurate forecasters and longer lead times.

"In addition to the added sensors higher resolution technology, NPP will give us critical information from the entire Earth surface twice a day. This additional data will give National Weather Service forecasters more knowledge days in advance about the strength of a storm. This will allow communities to get ready for impacts, like floods that devastated the Mississippi-Missouri river vallies this spring, well in advance. We alerted our customers across the nation one-to-two months before, and I see with the more-accurate data we'll have more precision in our forecasts, more certainty in our alerts so that preparations that are costly can begin earlier and more efficiently.

"In summary, NPP will improve our forecasting skill for major weather events that have severe and lasting impacts on people's lives -- snow storms, floods, drought, heatwaves and hurricanes. By investing in this advanced satellite technology, society as a whole will be moving forward toward a weather-ready nation that is no longer victimized by the Earth's often violent outbursts."

The first stage helium and nitrogen systems have been pressurized.

Typically at this point in a Delta 2 rocket countdown, the launch team loads 10,000 gallons of highly refined kerosene fuel into the first stage. However, this operation was completed Thursday afternoon prior to retraction of the mobile service tower.

The kerosene, called RP-1, will be consumed along with liquid oxygen by the first stage RS-27A main engine and twin vernier steering thrusters during the initial four-and-a-half minutes of flight.

Filling of the stage with cryogenic liquid oxygen will begin about an hour from now.

No problems are being reported in tonight's activities and liftoff continues to be targeted for 2:48 a.m.

Hazardous operations to pressurize the first and second stage helium and nitrogen systems and the second stage fuel and oxidizer tanks are getting underway at Space Launch Complex 2.

The rocket's control system and guidance computer are being turned on.

COUNTDOWN BEGINS! The three-hour Terminal Countdown sequence has been initiated for today's launch of the Delta 2 rocket from Vandenberg Air Force Base in California. The booster will carry into orbit the NPP climate and weather observatory.

Liftoff from the Space Launch Complex 2 pad is scheduled for 2:48:01 a.m. local (5:48:01 a.m. EDT; 0948:01 GMT). Today's available launch window is open for 9 minutes and 10 seconds in duration.

Between now and the launch time, the rocket's guidance system will be activated, onboard helium and nitrogen tanks brought up to pressure, the liquid oxygen supply loaded into the first stage, checks performed on the safety system and steering tests conducted on the engines.

This is a standard countdown for the Delta 2, a typical timeline to ready the vehicle for flight. Pre-planned holds are built into the countdown at the T-minus 15 and T-minus 4 minute points. The first will last 20 minutes; the second will be 10 minutes in length. Those pauses are designed to give the launch team the opportunity to work problems or catch up on items perhaps running behind schedule.

Polls of the various launch team members and managers occur during that T-minus 4 minute hold to ensure everything is ready to proceed into the busy final minutes that see the rocket put on internal power, pressurized and armed for liftoff from California's Central Coast.

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"Man stations for Terminal Count." That's the call to the launch team in preparation for a readiness check to ensure all consoles are "go" for starting the countdown 15 minutes from now.

T-minus 150 minutes and holding. At this time, the countdown is entering a planned 60-minute built-in hold. The Terminal Countdown begins once the hold concludes.

Launch remains targeted for 2:48 a.m. local (5:48 a.m. EDT; 0948 GMT) from Vandenberg Air Force Base in California.

Check out this additional photo collection of the Delta 2 rocket taken during gantry rollback and sunset at the launch pad.

Stunningly spectacular sunset rollback of the mobile service gantry this evening!

See our photo gallery.

Under brilliantly clear skies and the setting sun as backdrop on this late October afternoon on the California coast, the Delta 2 rocket has been unveiled from the mobile servicing gantry at Vandenberg's Space Launch Complex 2.

A crowd of news media and VIPs watched over the past few minutes as the cocoon-like tower was wheeled away to get activities underway for tonight's launch countdown.

Rollback began at 5:20 p.m. and was completed about 15 minutes later.

The 177-foot tall service tower was used to stack the two-stage vehicle, the nine strap-on solid rocket motors and the NPP payload atop the pad's launch mount. The tower also provided the primary weather protection and worker access to the rocket during its stay at the oceanside complex on North Vandenberg.

Ground teams will spend the next few of hours getting the pad configured and secured in advance of the Terminal Countdown. Launch remains targeted for 2:48 a.m. local (5:48 a.m. EDT; 0948 GMT).

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Good afternoon from just outside the perimeter of Space Launch Complex 2. Reporters and photographers are gathering to head inside the pad to cover the gantry rollback event, which will reveal the Delta 2 rocket for flight. But with no cellphones allowed within the pad, we can't post an update when the tower begins to move. But will give a full status and photo gallery as quickly as possible afterwards.

The official weather outlook issued before going into the countdown still predicts no chance of violating any of the launch rules for Friday's predawn blastoff.

"High pressure continues to build in the Great Basin and the Pacific today. Offshore flow is keeping the marine layer well off the coast. This wind pattern will continue through launch and is resulting in unrestricted visibility and favorable sky conditions today through T-0," Air Force forecasters say.

The launch time conditions are expected to include cirrus clouds at 25,000 feet, clear visibility, surface winds from the east of 8 to 12 knots and maximum upper level winds from the west of 50 knots at 40,000 feet.

Watch this page for live coverage overnight, plus live streaming video!

NASA launch commentator George Diller shows his console inside the Mission Director's Center at Vandenberg Air Force Base.

See our photo gallery.

Take a look around Vandenberg Air Force Base's Space Launch Complex 2, the West Coast home of the United Launch Alliance Delta 2 rocket.

See our photo gallery.

Photographers for United Launch Alliance, the LA Daily News and Spaceflight Now set up their sound-activated cameras around Vandenberg Air Force Base's Space Launch Complex 2 pad to cover the Delta 2 rocket blasting off with the NPP climate and weather observatory.

See our photo gallery.

The launch team is resting at this hour before the countdown operations kick off later today. Liftoff remains on schedule for tomorrow morning at 2:48 a.m. local time (5:48 a.m. EDT).

"We have worked closely with the NPP spacecraft team and with our partners in (Kennedy Space Center's) Launch Services Program for several years preparing for this launch. The integration work is complete, the launch processing is in its final stages and we are ready to launch the NPP spacecraft into polar Earth orbit," said Vernon Thorp, ULA's program manager for NASA missions.

"We are proud to serve a critical role in delivering one-of-a-kind NASA payloads to orbit in support of the global science community...NPP represents the culmination of years of hard work by NASA and the ULA launch teams, and we anticipate our reliable Delta 2 will safely deliver the spacecraft into its desired orbit."

An advanced environmental satellite to observe our home planet and its workhorse booster have been cleared for launch Friday morning from California.

The Launch Readiness Review occurred today to verify the NPP spacecraft and Delta 2 rocket are standing in perfect shape for blastoff at precisely 2:48:01 a.m. local (5:48:01 a.m. EDT; 0948:01 GMT) from Vandenberg Air Force Base.

"This morning we held a successful Launch Readiness Review and received approval from senior NASA and ULA management, as well as spacecraft and Range agencies to proceed with initiating our launch countdown," said Tim Dunn, the NASA launch director.

Out at Space Launch Complex 2 today, pre-flight testing of the Delta 2 vehicle was being wrapped up ahead of the countdown operations.

The C-band link used for tracking the rocket as it flies downrange and the command receiver decoders in the vehicle's safety system were checked with the Western Range.

Technicians also performed a final azimuth alignment for the rocket's RIFCA guidance computer and ran steering checks on the rocket's first and second stage engine nozzles.

With today's LRR giving the okay to continue with preparations and enter into the actual countdown, the team plans to load highly refined kerosene fuel into the first stage Thursday afternoon, followed by procedures to ready the mobile service gantry for retraction from around the 12-story rocket. The tower rollback is anticipated at approximately 4:45 p.m. local time (7:45 p.m. EDT).

The Terminal Countdown will start at 11:48 p.m. local time (2:48 a.m. EDT), beginning the formal three-hour process to bring the rocket to life, load the liquid oxygen for the main engine, conduct extensive final testing and then send it into orbit.

Friday's launch opportunity extends 9 minutes and 10 seconds to ensure NPP reaches the desired orbit. The window closes at 2:57:11 a.m. local (5:57:11 a.m. EDT; 0957:11 GMT)

Watch this page for live updates and streaming video during the countdown and NPP's trek to orbit aboard the Delta rocket.

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The pre-launch news conference is coming up in a few minutes from Vandenberg Air Force Base. You can watch it live in our streaming video.

The weather outlook for Friday's launch opportunity remains perfect for the Delta 2 rocket's climb from California, according to the latest forecast issued by Air Force meteorologists this morning.

"A cold frontal boundary pushed through the Central Coast area earlier this morning causing the disruption of the marine layer over Vandenberg AFB. This frontal passage has contributed to the improved visibility and sky conditions. High pressure begins to build in the Great Basin and over the Pacific. Offshore flow will set up on Thursday, keeping the marine layer well offshore through Saturday," meteorologists report.

Conditions at the 2:48 a.m. PDT launch time are predicted to include just a few high cirrus clouds at 25,000 feet, unrestricted visibility, easterly winds 8 to 12 knots and a temperature between 47 and 52 degrees F.

The Launch Readiness Review has concluded and given the "go" to continue with Friday's liftoff plans. This morning's meeting examined the status of the Delta rocket, the NPP spacecraft, the network of ground support and the weather forecast. The review culminated with official consensus to press ahead with countdown operations starting Thursday afternoon.

Join us on this page for live streaming video of the pre-launch news conference and payload briefings starting at 1 p.m. local (4 p.m. EDT; 2000 GMT) today on this page.

Mission officials will convene the Launch Readiness Review today at Vandenberg Air Force Base to confirm all systems are set to enter into the countdown for Friday's early morning liftoff.

After the LRR concludes, The pre-launch press conference is planned for 1 p.m. local (4 p.m. EDT; 2000 GMT) with the NASA launch director, ULA's program manager, NPP officials and the weather officer.

That briefing will be followed by a look at the NPP science objectives and then a presentation on the student CubeSats also flying on the Delta 2 rocket.

Originally conceived as a testbed satellite to prove the advanced designs for future U.S. government spacecraft, the NPP mission blasting off Friday has been thrust to an entirely new level of importance for meteorologists now facing a gap in data from space.

Read our full story.

Roughly the size of a sports utility vehicle, the environmental satellite launching from America's western spaceport Friday morning carries a suite of modernized instruments to see Earth's weather with crisper clarity than its decades of predecessors.

Read our satellite story.

Technicians are finishing the second stage fueling operations today by loading the Aerozine 50 hydrazine into the Delta 2 rocket as activities remain on track for liftoff.

Also today at Vandenberg, meteorologists issued their first weather forecast for Friday's launch opportunity. And that outlook is excellent with a 100 percent chance of acceptable conditions. Most notably, there's no fog predicted at launch time that could hamper watching the rocket thunder into the middle-of-the-night skies.

The forecast calls for only a few high cirrus clouds at 25,000 feet, unrestricted visibility, easterly winds of 10 to 15 knots and a temperature between 47 and 52 degrees F.

If the launch slips to Saturday for some reason, meteorologists say the ideal conditions will continue.

A satellite whose mission will touch the lives of everyone on Earth by taking the planet's environmental pulse daily for global weather forecasting and meticulous tracking of the changing climate will be launched into space Friday morning atop what's potentially the final Delta 2 rocket.

Read our launch preview story.

Storable hypergolic propellants are being loaded into the Delta 2 rocket's second stage today and tomorrow in preparation for Friday's predawn blastoff.

Technicians at Vandenberg Air Force Base's Space Launch Complex 2 began filling the stage with nitrogen tetroxide oxidizer this morning. The hydrazine propellant mixture will be placed aboard tomorrow.

The fuels will power the stage's Aerojet-made main engine during the two firings needed to propel the NPP satellite into the proper polar orbit.

Officials do not take the decision to start loading the rocket lightly. Commencing the second stage fueling is a major milestone in preparing for launch, one that starts a "clock" of 37 days for the rocket.

That "clock" is based on how long the stage remains certified to fly after the storable propellants begin flowing into the vehicle. Exposure to the fuels limits the lifetime for seals and other parts of the stage.

Meanwhile, members of the launch and management teams are holding a countdown dress rehearsal today to practice countdown scripts, problem solving and procedures.

Liftoff remains on target for 2:48 a.m. local (5:48 a.m. EDT; 0948 GMT) Friday morning at the opening of a 9-minute launch window.

See how the United Launch Alliance Delta 2 rocket was assembled on its Vandenberg Air Force Base pad for the NPP weather satellite launch in this photo gallery.

The Delta 2 rocket and the NPP spacecraft underwent the Flight Readiness Review today to assess the progress of work and grant approval to proceed with loading the storable hypergolics into the second stage.

A NASA spokesperson says there are no outstanding issues from the FRR and the "go" was given to proceed with fueling on Monday as planned.

Installation of the Delta 2 rocket's nose cone is underway in the cleanroom of Vandenberg Space Launch Complex 2 gantry today.

The 10-foot-diameter composite fairing will protect the NPP spacecraft during the climb through Earth's atmosphere in the initial 4 minutes and 41 seconds of flight. It is jettisoned in two halves just after ignition of the second stage at altitude of 84 miles while traveling over 12,000 miles per hour.

The launch campaign was paused briefly this week to complete some engineering analysis that officials wanted wrapped up before moving ahead with preflight operations. The extra work caused a one-day slip in the launch date, bumping liftoff to next Friday morning at 2:48 a.m. local.

Among the other activities that have occurred in the past few days, ordnance installation and connections were made on the rocket, the CubeSat payloads were mounted to the launcher and closeouts of the NPP satellite were performed.

The Flight Readiness Review is scheduled for tomorrow and the filling of the second stage with storable hypergolic propellants will see the nitrogen tetroxide oxidizer loaded aboard next Monday and the hydrazine fuel mixture on Tuesday.

DELAY. The planned launch date has been pushed back by a day, to October 28 at 2:48 a.m. local (5:48 a.m. EDT). The decision to move the launch gives engineers time to complete their work before proceeding with the next step in the pre-flight process -- installing the rocket's nose cone that was supposed to occur today. Needing more time to finish reviews and no slack left in the schedules, officials opted to insert an additional day into the timeline and slip the launch, a spokesperson said.

The Integrated Systems Test for the United Launch Alliance Delta 2 rocket and the NPP spacecraft was run Saturday to confirm the combined booster and payload are ready for their departure from Earth next week.

The thorough electrical test simulated the countdown and the rocket's trek from liftoff through spacecraft deployment nearly an hour into flight. Officials reported all went well.

NPP and the Delta have been operating on separate paths during manufacturing and assembly. But they finally met last Thursday, getting bolted together in preparation for the crucial ascent on October 27 to propel the spacecraft off the ground and into Earth orbit.

The spacecraft, built by Ball Aerospace, underwent the on-pad functional test Friday. That check was designed to confirm the satellite remained healthy following transport to Complex 2.

Meanwhile, activities underway today are focused on installing the deployment mechanism with the tiny CubeSat secondary payloads hitching a ride aboard the Delta 2.

Achieving a "monumental milestone" with 14 days left until blastoff, the NPP climate and weather observatory was transported to its launching pad at Vandenberg Air Force Base and mounted atop the Delta 2 rocket today.

About the size of an SUV, the satellite will fly 512 miles above the planet to monitor global environmental conditions for near-term weather forecasters and long-range climate trackers.

"NPP's observations of a wide range of interconnected Earth properties and processes will give us the big picture of how our planet changes," said Jim Gleason, NPP project scientist. "That will help us improve our computer models that predict future environmental conditions. Better predictions will let us make better decisions, whether it is as simple as taking an umbrella to work today or as complex as responding to a changing climate."

Getting the craft into orbit moved a step closer this morning when NPP was trucked up the road from the commercially-run Astrotech processing facility to NASA's Space Launch Complex 2 at the California military base.

Pad technicians attached an overhead crane that hoisted the satellite into the gantry and carefully positioned it onto the rocket's second stage for attachment.

Now begins the final two weeks of pre-flight preparations including combined testing between the satellite and rocket on Saturday, installation of the booster's nose cone next Wednesday, the Flight Readiness Review next Thursday, the countdown dress rehearsal next Friday and loading storable propellants into the second stage planned for oxidizer on October 22 and fuel on October 24.

The Launch Readiness Review will be held on October 25 to grant approval to enter into the countdown operations on the afternoon of October 26 for the middle-of-the-night liftoff on October 27.

Despite a one-day delay delivering the payload to the pad due to high winds Wednesday, launch remains scheduled for October 27 at 2:48 a.m. local time (5:48 a.m. EDT; 0948 GMT). The launch window extends for 9 minutes each day.

"I'm very excited and proud of my NPP team's accomplishments and we look forward to a great mission," said Ken Schwer, NPP project manager.

The NPP spacecraft traveled to the launch pad this morning. Crews will be working over the next few hours to lift the satellite atop the rocket.

Coming up at 1 p.m. EDT (1700 GMT), we'll have live streaming video coverage of the NPP overview briefing from NASA Headquarters. You'll hear from project officials and get an introduction to the mission.

Meanwhile, today's planned move of the NPP climate and weather observatory from the Astrotech payload processing building to the launch pad was scrubbed due to high winds.

The NPP launch date is being moved by two days to October 27 as mission managers revise the pre-flight schedule because of two technical issues with the Delta 2 rocket.

"During systems testing, a hydraulic system leak was detected and the cause was found to be a small crack in a hydraulic tube. A replacement tube was manufactured, installed, and retested. All other similar tubes have been inspected and confirmed to be free of any defects," NASA said in a statement today.

"Also, a flexible fabric collar connecting two engine system exhaust ducts was found to be damaged following pressurized leak testing. The damaged fabric collar is being removed and replaced," the NASA statement said.

Delivery of the NPP satellite to Space Launch Complex 2, originally planned for October 7, has been reset for October 12.

An advanced polar-orbiting weather observatory took a 1,600-mile roadtrip from Colorado to California this week, arriving at the satellite's Vandenberg Air Force Base launch site after the 40-hour journey.

A crew of 16 people including team members from satellite-builder Ball Aerospace and NASA's project group escorted the spacecraft on the long-awaited shipment.

"It was a good trip, no incidents," said Scott Tennant, Ball's program manager. "The guys commented...one-lane construction zones are kind of an adventure when you have a wide payload."

Valued at $1.5 billion, the satellite's mission will continue global weather monitoring and climate data records while covering virtually the entire planet twice per day from its 512-mile-high polar orbit.

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