NASA's new cosmic mapper successfully jettisoned a protective lens cover Tuesday, opening its infrared eyes to Universe for an unprecedented survey in 2010.

Read our full story.

With the promise to discover millions of objects never seen before and revolutionize our view of the Universe, NASA has launched its WISE observatory on a scouting expedition that will rewrite the road maps to the cosmos.

Read our launch story.

Launch photo galleries can be seen here.

Additional coverage for subscribers:
VIDEO: DELTA ROCKET LAUNCHES WISE OBSERVATORY PLAY
VIDEO: RETRACTION OF PAD'S MOBILE SERVICE GANTRY PLAY
VIDEO: NARRATED HIGHLIGHTS OF WISE LAUNCH CAMPAIGN PLAY
VIDEO: NARRATED HIGHLIGHTS OF DELTA 2 LAUNCH CAMPAIGN PLAY
VIDEO: DELTA/WISE PRE-LAUNCH NEWS CONFERENCE PLAY
VIDEO: WISE SCIENCE PREVIEW BRIEFING PLAY
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This is the 92nd consecutive successful Delta 2 rocket launch dating back to May 1997. The Delta 2's overall history since debuting in 1989 has achieved 145 successes in 147 flights.

Four more Delta 2 rockets are on the manifest over the next two years, including NASA's Aquarius oceanography spacecraft and the Italian COSMO 4 radar imaging satellite, both slated to fly in 2010 from Vandenberg. The NPOESS Preparatory Project weather satellite and NASA's GRAIL mission to the moon will follow in 2011 from Vandenberg and Cape Canaveral, respectively.

ULA also has five additional Delta 2 vehicles it hopes to use for additional launches in the future.

Today's flight occurred on the third anniversary of United Launch Alliance's first mission. Over the past 36 months, the company has completed 37 launches, including 22 Delta 2s, 11 Atlas 5s and 4 Delta 4s.

"The men and women of ULA are extremely proud of our mission success record while merging the Atlas and Delta product lines into one cohesive team. Launching successfully 16 times in one year is no easy feat and 37 missions in 36 months is certainly a high water mark for our industry. We look forward to a great 2010 with several critical missions ahead of us," Sponnick said.

"I congratulate NASA, the 30th Space Wing, and all of our mission partners on a successful launch campaign, which culminated in today's picture perfect launch," said Jim Sponnick, ULA's vice president for Delta. "My thanks to the NASA Kennedy Space Center Launch Services Program (LSP) for the outstanding teamwork demonstrated throughout the six ULA/NASA KSC launches this year."

"It feels good," NASA launch manager Chuck Dovale says.

T+plus 58 minutes, 25 seconds. The orbit achieved following the second burn by the second stage was on the mark. And the spacecraft separation event was nominal.

T+plus 55 minutes, 57 seconds. SPACECRAFT SEPARATION! NASA's Wide-field Infrared Survey Explorer has been released from the Delta 2 rocket's second stage, completing today's launch! The Universe mapper is on its way to discover millions of new objects across the cosmos.

At the heart of the spacecraft is a 16-inch telescope and four state-of-the-art infrared detectors containing one million pixels each, all packed inside a Thermos bottle-like tank filled with frozen hydrogen.

The lower structure holds the solar array for 551 watts of power, the navigation and control equipment, plus a large antenna for communicating with NASA's Tracking and Data Relay Satellites.

WISE weighs some 1,457 pounds and stands 9 feet tall, 6.6 feet wide and 5.7 feet deep.

"Our media guide says it's about the size of a polar bear. Now most of us don't run into polar bears, fortunately. The analogy I like is it's about the size of a race car. It is a highly efficient, custom machine," said Bill Irace, WISE project manager.

T+plus 54 minutes. Deployment of WISE is just over one minute away.

T+plus 53 minutes. At this point in the flight, the rocket is maneuvering itself to the proper orientation for release of the payload.

T+plus 51 minutes, 50 seconds. SECO 2 confirmed. The second stage engine has performed its approximate 8.5-second firing to propel spacecraft payload to the desired orbital perch.

T+plus 50 minutes, 40 seconds. One minute out from the burn. next firing by the Delta rocket's second stage is coming up in three minutes.

T+plus 50 minutes. Delta's second stage engine will reignite for a short firing to boost the elliptical orbit into a circular one. The targeted orbital parameters are 289.6 nautical miles at apogee, 282.1 miles at perigee and inclination of 97.504 degrees.

T+plus 48 minutes, 40 seconds. The next firing by the Delta rocket's second stage is coming up in three minutes.

T+plus 45 minutes. The rocket's turn to the orientation for engine restart is underway.

T+plus 40 minutes. A map illustrating the rocket's flight carrying the WISE satellite can be viewed here.

T+plus 33 minutes. The WISE spacecraft, still firmly attached to the launch vehicle, is passing over Antarctica.

T+plus 30 minutes. The rocket is coasting until the second stage restarts its engine at T+plus 51 minutes, 40 seconds for a brief 8.5-second firing to put the vehicle into a near-circular sun-synchronous orbit above Earth. Deployment of WISE from the launch vehicle is expected to be confirmed about 55 minutes after liftoff.

T+plus 17 minutes. Shortly after the rocket rocket enters this temporary orbit, it maneuvers itself into the proper orientation for the coast.

At T+plus 42 minutes, 30 seconds, the second stage will begin another maneuver get into the correct position for the next engine firing.

T+plus 14 minutes, 20 seconds.The Delta 2 rocket is 101.7 miles in altitude, 2,112 miles downrange and traveling at 16,886 mph.

T+plus 14 minutes. Live telemetry continues to be received via NASA's Tracking and Data Relay Satellite System. Today's launch is the first Delta 2 flight to use TDRS.

T+plus 12 minutes. The orbit achieved appers right on target.

T+plus 10 minutes, 26 seconds. SECO 1 has been confirmed. The second stage's Aerojet-made engine completed its initial burn for the launch. Delta and WISE should be in the preliminary parking orbit.

T+plus 9 minutes. The Delta rocket rocket has flown out of range from the ground tracking station network. NASA's orbiting Tracking and Data Relay Satellite System has acquired the rocket's telemetry signal as the Delta travels away from Vandenberg.

T+plus 8 minutes, 30 seconds. About two minutes remain in this burn of the second stage engine to achieve the intended parking orbit. The targeted orbit should be 299 nautical miles at apogee, 100 miles at perigee and inclined 97.5 degrees.

T+plus 8 minutes, 15 seconds.The Delta 2 rocket is 101 miles in altitude, 749 miles downrange and traveling over 13,000 mph.

T+plus 7 minutes, 45 seconds. The second stage continues to fire normally.

T+plus 6 minutes, 45 seconds.The Delta 2 rocket is 93 miles in altitude, 497 miles downrange and traveling at 11,829 mph.

T+plus 6 minutes, 15 seconds.The Delta 2 rocket is 82 miles in altitude, 405 miles downrange and traveling at 11,333 mph.

T+plus 5 minutes, 50 seconds. Second stage engine pressure and the pitch and yaw control are normal.

T+plus 5 minutes, 20 seconds. The Delta 2 rocket is 73 miles in altitude, 277 miles downrange and traveling at 10,705 mph.

T+plus 5 minutes. The rocket's 10-foot-diameter nose cone enclosing the WISE spacecraft has been shed. The fairing is no longer needed, now that the Delta has climbed above the atmosphere.

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

T+plus 4 minutes, 39 seconds. MECO and staging confirmed. The first stage main engine cutoff, followed moments later by shutdown of the twin vernier steering thrusters. The spent stage then jettisoned.

T+plus 3 minutes, 50 seconds. The Delta 2 rocket is 39 miles in altitude, 79 miles downrange and traveling at 6,400 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 1 minute, 50 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. The trio of ATK-made solid rocket boosters have burned out of propellant. The Delta 2's first stage RS-27A main engine will be providing the sole thrust for the next few minutes.

T+plus 55 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 36 seconds. Delta has broken the sound barrier, rapidly accelerating on the power of its first stage main engine and the three ground-lit strap-on solid-fuel boosters.

T+plus 15 seconds. The launch vehicle is departing Vandenberg Air Force Base along an initial flight azimuth of 196 degrees, heading south for the trek downrange over the Pacific.

LIFTOFF! Liftoff of the Delta 2 rocket launching NASA's infrared eyes to map the Universe!

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 three ground-lit solid rocket motors then light at T-0 for liftoff.

T-minus 1 minute. All remains "go" for launch of the Wide-field Infrared Survey Explorer.

T-minus 75 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, 35 seconds. The WISE spacecraft has been declared "go" for launch.

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

T-minus 3 minutes and counting towards liftoff of Delta 347.

T-minus 3 minutes, 45 seconds. 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 through the final segment of the Delta 2 rocket's countdown to liftoff. Launch is set for the precise moment of 6:09:33 a.m. local time from Vandenberg Air Force Base, California.

Following liftoff, the vehicle will head southward as it climbs into orbit on a 55-minute flight to deploy its satellite payload.

Now five minutes from launch! The "go" has been announced to resume the countdown.

The WISE spacecraft has been configured for launch.

The cloud cover and the upper level winds are reported within limits at this time.

No contraints were reported in the poll. All appears in readiness for an on-time liftoff. Final instructions are being read to the launch team.

Launch team polling is underway to verify the rocket, payload, ground systems and weather are ready for liftoff.

Now just 10 minutes away from liftoff time.

WISE will become the 222nd primary payload put into space by the venerable Delta 2 rocket over the past 20 years. Here's a look at some other stats about today's mission. This will be:

The 347th Delta rocket launch since 1960

The 11th Delta of 2009

The 8th Delta 2 of the year

The 147th Delta 2 rocket mission since 1989

The 47th Delta 2 mission overseen by NASA

The 38th Delta 2 rocket launch from Vandenberg AFB

The 9th Delta 2 rocket to fly in the 7320 configuration

The WISE spacecraft is going to internal power for launch.

NASA launch manager Chuck Dovale has completed a poll to confirm the agency management team is "go" to proceed with the countdown.

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 at 6:09:33 a.m. local time (9:09:33 a.m. EST; 1409:33 GMT). However, this hold can be extended if the weather or a technical problem requires it.

Engineers continue to assess the upper level winds to determine if conditions are acceptable for the Delta 2 rocket to launch today.

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 planned hold is scheduled. Launch remains targeted for 6:09:33 a.m. local time (9:09:33 a.m. EST; 1409:33 GMT). weather permitting.

A readiness poll of the launch team confirms all is "go" to restart the countdown as scheduled.

The Delta rocket will be flying in its configuration known as the 7320-10 vehicle. The two-stage launcher is fitted with just three 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. Once the SRBs burn out and then separate 17 miles up, the kerosene-powered main engine will continue pushing the rocket to an altitude of 57 nautical miles.

The spent first stage will jettison to let the hydrazine-fueled second stage ignite and achieve a preliminary parking orbit of 100 by 299 miles some 10 minutes 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 8.5 seconds off the southern coast of Madagascar to reach a near-circular polar orbit above the planet.

The WISE spacecraft is expected to be released from the rocket 55 minutes after blastoff in a 282 by 290 nautical mile orbit inclined 97.5 degrees to the equator.

The second stage helium and nitrogen systems, plus fuel and oxidizer tanks has been pressurized.

T-minus 15 minutes and holding. Clocks have entered the next planned hold period during 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.

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The first stage engine steering checks just finished.

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

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 thrusters and second stage engine to ensure the rocket will be able to steer itself during launch.

The countdown is entering the final hour until the Delta 2 rocket soars away from the central coast of California carrying the Wide-field Infrared Survey Explorer spacecraft.

"WISE will survey the sky with much improved resolution and sensitivity than previous surveys. This means that WISE will get much sharper pictures and be able to see much fainter objects. As a result, it will see a few hundreds of millions of objects. Many of these are stars and galaxies that we can see at other wavelengths. But for millions of them, WISE will be the first time that we've ever seen these objects," says Ned Wright, WISE principal investigator at UCLA.

Loading of the Delta 2 rocket's first stage liquid oxygen tank has been accomplished. 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 last night. The second stage was filled with its storable nitrogen tetroxide and Aerozine 50 fuels a week ago. And the three strap-on booster rockets are solid-propellant.

Liquid oxygen loading is continuing. 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.

This approximate 25-minute process to fill the first stage liquid oxygen tank has been underway for 10 minutes. As the super-cold liquid oxygen continues to flow into the first stage, a bright white plume of vapors begins streaming from a vent on the rocket and the bottom of the vehicle ices over.

LOX loading begins. 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 cumulus cloud and thick cloud rules aren't being violated any longer. The upper level wind conditions continued to be watched, however.

The official "go" has been given to start liquid oxygen loading beginning at 4:34 a.m. local time.

The launch team is completing preparations for loading the rocket's first stage liquid oxygen tank.

NASA launch manager Chuck Dovale has completed a poll to confirm the agency management team is "go" for liquid oxygen loading. The actual start of LOX flow may be delayed a few minutes to watch that approaching rainshower and ensure it does stay clear of the pad.

The countdown is continuing at Vandenberg Air Force Base for launch. No technical issues with the Delta 2 rocket or WISE spacecraft are being reported by NASA.

Now two hours from launch.

A current check of the weather before proceeding into first stage liquid oxygen loading shows the cumulus cloud and thick cloud rules remain red. There is an area of rain about 11 miles to the northwest, but meteorologists believe the showers will not pass directly over the launch pad.

The forecast for this morning's launch time has been revised to includes low layers of clouds at 2,500 and 4,000 feet, some high cirrus at 25,000 feet, four miles of visibility with fog, north-northeasterly winds of 5-10 knots and a temperature in the low 50s F.

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 Sunday night prior to retraction of the mobile service tower.

The early fuel loading was performed to give the rocket added weight and stability while the Delta is exposed to the weather.

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.

The Delta team is keeping a close eye on upper level winds too. Weather balloons will be released throughout the countdown to measure the speed and direction of the winds aloft.

The weather is a potential concern for this morning's launch. At the current time, the rules governing cumulus clouds and the cloud thickness are being violated. The odds of acceptable conditions at liftoff time have dropped from 80 percent down to 60 percent.

The official forecast includes low layers of clouds at 1,000 and 2,000 feet, some high cirrus at 33,000 feet, four miles of visibility with fog, northerly winds of 5-10 knots and a temperature in the low 50s F.

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

And the launch team is starting the steps to pressurize the first and second stage helium and nitrogen systems and the second stage fuel and oxidizer tanks.

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 NASA's WISE infrared Universe mapper.

Liftoff from the Space Launch Complex 2 pad is scheduled for 6:09:33 a.m. local time (9:09 a.m. EST; 1409 GMT). Today's available launch window stretches 14 minutes and 18 seconds to 6:23:51 a.m.

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 normal 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.

A beautiful collection of photos taken at the launch pad showing the Delta 2 rocket poised for today's launch can be seen here.

T-minus 150 minutes and holding. Clocks have been paused for a planned 60-minute built-in hold. The Terminal Countdown remains scheduled to start at 3:09 a.m. local time (6:09 a.m. EST; 1109 GMT), beginning the formal three-hour process to bring the rocket to life for its launch.

Rollback of the service gantry at Vandenberg Air Force Base's Space Launch Complex 2 began a little after 10 p.m. local time (1 a.m. EST).

The 177-foot tall mobile tower was used to stack the two-stage United Launch Alliance vehicle, the three strap-on solid rocket motors and the WISE 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 couple of hours getting the pad secured in advance of the Terminal Countdown. Launch remains targeted for 6:09 a.m. local time (9:09 a.m. EST; 1409 GMT).

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.)

Activities are on schedule for Monday's early morning blastoff of the Delta 2 launcher. Pad crews plan to retract the mobile tower away from the rocket after 8:30 p.m. local time tonight.

Mission managers gather on station at 2 a.m. and the Terminal Countdown begins ticking at 3:09 a.m. local.

Watch this page for live updates throughout the morning's countdown and launch!

A mission management meeting this morning gave the "go" to remove the WISE observatory's ground cooling umbilical and commit to Monday's launch opportunity.

The Wide-field Infrared Survey Explorer has a unique helium umbilical that keeps the spacecraft's supply of frozen hydrogen chilled while on the launch pad. Once that cooling line is removed, the launch must occur within two days -- Monday or Tuesday.

If the Delta 2 rocket does not fly within the next couple of days, the umbilical must be reinstalled and two days of rechilling the hydrogen performed before the launch can be rescheduled. The servicing would ensure WISE is deployed in the best possible condition for its 10-month orbital project.

John Elwell, project manager of the WISE science instrument from the Space Dynamics Laboratory, Logan, Utah, explains why the satellite needs the supercold hydrogen to perform the infrared mapping mission.

"Because WISE takes pictures of infrared light, or heat, we have to keep the telescope and detectors themselves very cold. Otherwise, all we would see is our own heat. Sort of like going out in the middle of the night to look at the stars and shining a bright flashlight in your own eyes.

"To keep the optics cold, we put WISE into a giant Thermos bottle called a cryostat...The cryostat keeps the heat from the sun and Earth off the WISE instrument and it lets us keep the inside cold. But to get cold in the first place we need some ice cubes. For WISE, our ice is stored in donut-shaped tanks inside the cryostat.

"We don't use water ice for WISE because it's not cold enough. We filled the tanks with hydrogen ice, or solid hydrogen, which turns out to be a great ice cube us. It freezes at about the right temperature, -430 degrees F, and it takes a lot of heat to melt hydrogen ice, so our ice cubes last a long time. They'll keep us cold for about 10 months on orbit."

Repairs to the Delta 2 rocket's first stage vernier thruster have been completed at the Space Launch Complex 2-West pad, clearing the way for Monday's planned liftoff.

Technicians removed and replaced a suspect steering actuator after the thruster exhibited unexpected resistance during motion checks this week. Retesting of the system with the new actuator installed showed good readings, a NASA spokesperson said.

Weather forecasters are predicting decent conditions for Monday morning's attempt to launch the Delta 2 rocket and WISE spacecraft from Vandenberg Air Force Base, California.

"Unsettled weather will continue over the weekend as systems follow a fast-moving weather pattern. The last storm system will pass through VAFB Sunday morning. Rainshowers and clouds will decrease through the day," the weather team says.

"In the wake of the weekend's weather, a few cumulus clouds and isolated light rainshowers could linger into T-0."

Overall, there's an 80 percent chance of acceptable weather at the 6:09 a.m. PST launch time on Monday. The potential threat to violating launch rules comes in the form of cumulus clouds.

The outlook includes a low layer of clouds at 1,000 feet and some high cirrus at 35,000 feet, good visibility, rainshowers in the vicinity, northwesterly winds of 10-12 knots and a temperature in the low 50s F.

For the backup launch date on Tuesday morning, there's an 80 percent chance of good weather and only a slight concern for thick clouds.

Mission managers have approved plans to reschedule the Delta 2 rocket launch for Monday morning to lift NASA's WISE observatory into space.

A suspect component will be removed and replaced to resolve the technical problem with the first stage vernier steering thruster that prompted the launch postponement.

Monday's launch window extends from 6:09:33 to 6:23:51 a.m. local time (9:09-9:23 a.m. EST; 1409-1423 GMT).

The early weather forecast calls for an 80 percent chance of acceptable conditions on Monday.

Officials continue to assess a technical concern with one of the vernier steering thrusters on the Delta 2 rocket's first stage. Pre-flight testing Wednesday revealed an unexpected amount of resistance when the thruster was moved. The verniers gimbal to help steer the rocket during its initial four-and-a-half minutes of flight.

A late-day meeting is planned at Vandenberg tonight to review the status of troubleshooting.

The official launch date remains up in the air. The most recent update from NASA indicated that a Saturday morning countdown was the earliest option. But there's signs that a further slip to Sunday is possible.

Here is NASA's statement on the delay:

"The launch of NASA's Wide-field Infrared Survey Explorer (WISE) mission scheduled for Friday, Dec. 11 has been delayed. During final systems checks of the Delta 2 rocket Wednesday in preparation for flight, an anomaly in the motion of a booster steering engine was detected. In order to give engineers the additional time required to troubleshoot the issue, the scheduled Dec. 11 launch attempt was delayed a minimum of 24 hours."

The WISE team says the next launch attempt will be Saturday morning at 6:09 a.m. local time (9:09 a.m. EST; 1409 GMT).

Still no official word on why this 24-hour delay from Friday has occurred.

DELAY. Launch of the WISE spacecraft has been postponed. Information about the reason behind the delay and a new target date have not yet been released by NASA.

The Delta 2 rocket is poised to deliver NASA's WISE telescope into space where it will map the Universe and uncover millions of new objects never seen before, but a dismal weather forecast and a unique twist to launch preparations will force officials to make an early decision about Friday's countdown.

"I have worked on WISE for 12 years, it's been a long haul and it is almost ready to launch. What I'm looking forward to this year for Christmas is WISE data," said Ned Wright, the mission's principal investigator from UCLA.

It is Mother Nature that's likely to decide exactly when the Wide-field Infrared Survey Explorer is shot into orbit for its revolutionary mission to scan the cosmos. Forecasters are predicting an 80 percent chance of weather prohibiting launch both Friday and Saturday mornings at Vandenberg Air Force Base in California.

Thick clouds and rain are the main threats for violating the strict weather rules during the 14-minute opportunity available each day to launch the rocket. The window extends from 6:09 to 6:23 a.m. local (9:09-9:23 a.m. EST).

The outlook begins to improve on Sunday and forecasters expect good conditions on Monday.

Deciding when to attempt the launch is unusually important for the WISE mission because the observatory is loaded with frozen hydrogen that will keep the telescope and its infrared optics supercold for the 10-month mapping mission.

At approximately Launch Minus-19 hours, or 11 a.m. local Thursday, pad workers are scheduled to disconnect the helium cooling umbilicals to the WISE spacecraft. If that event occurs as planned, launch would have to occur within the next two days -- Friday and Saturday -- or else be postponed into the following week.

While the spacecraft sits on the pad, the hydrogen will begin to warm. If the satellite isn't launched within two days of being unplugged from the cooling lines, engineers will require the helium umbilicals be reconnected for two days of re-chilling.

The scenario means, in basic terms, the team can get two launch opportunities, followed by two days of servicing work before attempting another countdown.

"That's not common for a launch like this. So we're working with the NASA and ULA people to get those cooling days on rainy days and the launch attempts on clear days," said Bill Irace, the WISE project manager from NASA's Jet Propulsion Laboratory.

"We have a two days on, two days off kind of posture. If we were to count down and not make the 11th and 12th, we would have to stand down for the 13th and 14th, let them go do some cryogenic operations and we'd be back after that. It's quite complicated," said Chuck Dovale, the NASA launch director.

Given the critical nature of the L-19 hour decision, officials will receive a full weather briefing Thursday morning before making the call of whether to proceed onward or not.

"Because we have some challenging weather ahead of us, we're going to have one last tag up and see what the forecast for Friday would bring. This will allow the WISE spacecraft to disconnect their cryogenic operations and commit to launch," Dovale said.

If the choice is made to shoot for the Friday launch, kerosene fuel will be loaded into the rocket's first stage at 7 p.m. local and the mobile service gantry's retraction away from the vehicle should happen between 8:30 and 10:30 p.m. local.

Mission managers gather on station at 2 a.m. and the Terminal Countdown begins ticking at 3:09 a.m. local Friday.

"The launch team is ready, we have been through all of NASA's reviews," Dovale said.

"I can report that the instrument and the satellite are ready to go, the flight team is ready to go and the operations team is ready to launch and operate WISE," Irace added.

Rocket specialists prepping a Delta booster for blastoff from California and the team behind a new NASA space observatory awaiting its trek to orbit Friday morning will gather for a final round of readiness reviews Wednesday, but a gloomy weather forecast is tempering hopes for an on-time launch.

Liftoff from Vandenberg Air Force Base is scheduled to occur during a precise launch window extending from 6:09:33 to 6:23:51 a.m. local time Friday (9:09-9:23 a.m. EST; 1409-1423 GMT).

The two-stage rocket will carry the Wide-field Infrared Survey Explorer, a spacecraft that will map the sky with unmatched sensitivity to reveal asteroids, comets, brown dwarfs, ultraluminous galaxies and new born stars never seen before.

But getting WISE off the ground will depend on the weather. A series of storms rolling ashore from the Pacific has brought rainy conditions to the launch site and more is expected in the coming days. In fact, meteorologists say there's an 80 percent chance that the weather will prohibit a launch on Friday and also during Saturday's backup opportunity.

"Weak high pressure is building in behind Monday's system ushering in colder than normal temperatures for the Central Coast. The good weather will be short-lived as the ridging will break down Thursday ahead of the next system. Rainshowers will begin at Vandenberg AFB Thursday afternoon accompanied by southeasterly winds. The winds will decrease down to 10 knots gusting to 15 knots after midnight," forecasters report.

At launch time Friday, the outlook calls for overcast skies with clouds from 1,500 to 8,000 feet, prompting an 80 percent likelihood of violating the thick cloud rule. Moderate rainshowers are likely through the countdown and into the launch window, forecasters add, resulting in a 60 percent chance of being "no go" for the disturbed weather rule, a 60 percent chance for moderate precipitation below 10,000 feet and 20 percent for precipitation above 10,000 feet.

Looking to backup launch opportunity on Saturday morning, the odds aren't any better.

"Another system rides a strengthening jet stream into California for Saturday, reinforcing Friday's inclement weather," meteorologists say.

Overcast skies will continue from 1,500 to 12,000 feet, causing an 80 percent probability of violating the thick cloud rule. Moderate rainshowers will plague the region through launch time, resulting in 60 percent chance of "no go" for the disturbed weather rule, 60 percent for moderate precipitation below 10,000 feet and 20 percent for precipitation above 10,000 feet.

In addition, winds are expected to kick up and produce gusts to 25 knots, yielding a 40 percent chance of violating the launch wind limit.

Hoping to catch a break in the weather, technicians are continuing with pre-flight work at the Space Launch Complex 2-West pad. The rocket's second stage was loaded with its storable propellants on Monday.

Watch this page for full coverage over the next few days. We'll also have live play-by-play updates and streaming video coverage of the launch!