Mission control in Houston has confirmed the Orion spacecraft is powered down and handed over control of the capsule to the recovery team in the Pacific Ocean.

The ground team will hook up the capsule to a tow line and winch it into the well deck of the USS Anchorage for the trip back to port in San Diego, where it is expected to arrive early Monday.

Recovery crews in small boats have reached a point about 125 yards from the Orion spacecraft. They will wait for the final power-down of the capsule about an hour after splashdown before moving in closer.

The Orion spacecraft's forward bay cover, drogue chutes and pilot chutes -- which were expected to be retrieved from the ocean -- were not able to be recovered, NASA says. But the Orion crew module is stable in the ocean and ground teams have already reached the capsule's main chutes.

Orion splashed down at 23.6 degrees north latitude, 116.46 degrees west longitude.

No hazardous conditions are reported in the vicinity of the Orion spacecraft, and no leaks are reported by the recovery team.

U.S. Navy and NASA recovery teams -- stationed on ships, inflatable boats and in helicopters -- are racing to the splashdown scene to begin safing the spacecraft.

Air bags have inflated to stabilize the capsule in the water.

Orion is reported in the Stable 1 configuration.

Splashdown confirmed!

Orion is less than 1,000 feet from splashdown.

Three main parachutes have unfurled!

Orion's forward bay cover and two 23-foot-diameter drogue chutes have deployed.

Orion is now at 60,000 feet and traveling below the speed of sound. Parachute deployments begin momentarily.

Signals have been re-acquired from Orion.

Entry interface confirmed. The Orion spacecraft is falling back into the atmosphere over the Pacific Ocean at an altitude of 400,000 feet.

A series of 11 parachutes will unfurl to slow down Orion's velocity, which will go from 20,000 mph to 0 mph in 11 minutes. The three 116-foot-diameter main parachutes will deploy at 11:25 a.m. EST (1625 GMT), about three minutes before splashdown.

Mission control expects to lose communications with the Orion spacecraft for more than 2 minutes between an altitude of 347,000 feet and 151,000 feet. The intense plasma shield around the capsule during re-entry will prevent a stable data link during this period.

The Orion spacecraft is fitted with a 16.5-foot-diameter heat shield made of an ablative material called Avcoat. The Avcoat material is supposed to partially burn away in the 4,000 degree Fahrenheit temperatures Orion will experience during re-entry.

Orion's heat shield is the largest of its kind. Orion's backshell, which will see less severe temperatures is covered with black tiles similar to the ceramic heat shield used on the space shuttle.

The Orion capsule has completed a 10-second thruster firing, one of the last major tasks before the critical re-entry which begins at 11:18 a.m. EST (1618 GMT).

Mission control in Houston has approved a command to keep Orion powered up for an hour after splashdown to gather bonus data on how the capsule fares after it reaches the Pacific Ocean. Engineers want to know how hot it gets inside the capsule during and after re-entry before a crew flies aboard Orion.

Mission control in Houston has approved a command to keep Orion powered up for an hour after splashdown to gather bonus data on how the capsule fares after it reaches the Pacific Ocean. Engineers want to know how hot it gets inside the capsule during and after re-entry before a crew flies aboard Orion.

The Delta 4's second stage has performed a 62-second burn to move away from the Orion spacecraft and set up for a destructive re-entry north of Hawaii.

Crew module separation! The Orion spacecraft is now flying free of the Delta 4 rocket and a dummy service module.

The expected splashdown point is at 23.61 degrees north latitude, 116.46 degrees west longitude -- 275 miles west of Baja California and 630 miles southwest of San Diego, where the U.S. Navy recovery team will return the capsule to port.

The flight dynamics officer in mission control reports the Orion spacecraft's splashdown target is just 1.5 miles from the location predicted before the flight. The capsule will experience a force of 8.2g during re-entry, nearly twice the force encountered by astronauts returning to Earth aboard Soyuz spacecraft.

The Orion spacecraft is passing through its peak altitude now -- 3,604.2 miles above Earth. That is 15 times higher than the orbit of the International Space Station.

Orion's fall back to Earth begins now, and Earth's gravity will pull the capsule back toward the ground at 20,000 mph.

Splashdown is scheduled for 11:29 a.m. EST (1629 GMT).

The Orion spacecraft's reaction control system has been activated and is ready to help guide the capsule's descent through the atmosphere. The capsule carries two strings of six hydrazine-fueled rocket jets controlling the craft's pitch, roll and yaw orientation.

An Ikhana drone aircraft has arrived over the Orion spacecraft's splashdown zone in the Pacific Ocean to capture live video of the capsule's parachute-assisted descent.

The two recovery ships -- the USS Anchorage and the USNS Salvor -- will deploy helicopters and inflatable boats shortly.

Orion's current altitude is 780 miles as the capsule begins heading through a radiation belt. Cameras on-board the capsule will be powered down for this first of two radiation belt passages on today's flight.

Many satellites heading for high-altitude orbits pass through the Van Allen radiation belts, but engineers want to know how Orion's human-rated computers respond to the passage. All of Orion's missions to deep space will go through this region of space.

"We kind of know what this radiation belt looks like," Geyer said. "The difference is these particular computer chips -- we've tested them on the ground in certain conditions. There are universities where we can test them, but you really need to fly them. "What happens is this radiation can actually cause what we call an upset -- it can cause a glitch in the data. The computers are smart enough to know if they've got funny data and they will stop and reset."

SECO 2. The RL10 engine has completed a "perfect" burn, according to NASA TV commentator Rob Navias.

The RL10 engine is firing again to push Orion to a peak altitude of 3,600 miles, 15 times higher than the International Space Station and farther from Earth than any human-rated spacecraft has traveled since 1972.

As NASA TV airs views from the Orion spacecraft in orbit, the Delta 4 rocket's RL10 upper stage engine is a few minutes from firing to boost the capsule to a higher altitude.

The engine will generate nearly 25,000 pounds of thrust for the burn, which is expected to last 4 minutes, 43 seconds.

Conditions in the Orion capsule's splashdown zone 600 miles southwest of San Diego are reported favorable for recovery of the spacecraft. Winds are out of the northeast at about 11 knots, and wave heights are within limits.

Mike Hawes, Lockheed Martin's Orion program manager, says the Orion flight test is going well so far following liftoff at 7:05 a.m. EST (1205 GMT).

The first of many key events to be tested on the Orion spacecraft today were the release of a three-piece aerodynamic fairing from the capsule's dummy service module and the jettison of the craft's launch abort tower.

"The (separation of the) panels and the launch abort system were very important to us," Hawes said.

He said the Orion flight control team at NASA's Johnson Space Center in Houston is downloading the first data file containing engineering information recorded by instrumentation aboard the capsule. More data will be downlinked throughout the mission, but all the data won't be retrieved until after splashdown.

The second burn of the Delta 4's RL10 upper stage engine is coming up at 9 a.m. EST (1400 GMT).

"That's really the critical burn," Hawes said. "That's what gets us the high apogee altitude and also sets us up for re-entry. We know what our true re-entry profile is going to be once we get through that burn."

Restart of the Delta 4 upper stage's RL10 engine is set for 9 a.m. EST (1400 GMT) to propel Orion into a high-altitude orbit reaching 3,600 miles above Earth. This maneuver is required for Orion to achieve the 20,000 mph speed necessary for the crucial re-entry test.

T+plus 19 minutes. A perfect orbit insertion. Orion is flying 554 by 115 miles.

T+plus 17 minutes, 21 seconds. SECO 1. The upper stage engine has shut down after the first of two planned firings to inject the Orion spacecraft on its two-orbit flight.

T+plus 14 minutes, 15 seconds. The RL10 engine is burning a mixture of liquid oxygen and liquid hydrogen cryogenic propellants.

T+plus 12 minutes, 20 seconds. Velocity 14,497 mph.

T+plus 11 minutes. Rock steady controls on the upper stage engine.

T+plus 10 minutes. Good engine control. Velocity of 13,711 mph.

T+plus 9 minutes, 25 seconds. Live views being received from Orion.

T+plus 7 minutes. Still looking good as Delta arcs over the Atlantic.

T+plus 6 minutes, 46 seconds. The aerodynamic fairing panels and launch escape tower have been jettisoned from the Orion spacecraft.

T+plus 6 minutes, 3 seconds. Engine start! The Aerojet Rocketdyne RL10B-2 cryogenic rocket engine is up and burning for the first firing during today's launch of the Delta 4-Heavy.

T+plus 5 minutes, 47 seconds. Pyrotechnics have detonated to jettison the spent center Common Booster Core. The rocket's upper stage and attached payload are now flying free.

T+plus 5 minutes, 40 seconds. Main engine cutoff! The center booster's RS-68 engine has finished firing and shut down.

T+plus 4 minutes, 30 seconds. The center Common Booster Core's RS-68 engine has revved up to full throttle for the Delta 4-Heavy rocket's on-going journey to space. The booster is identical to the outer strap-on stages, carrying the same propellant supply and engine package, but it employed a more conservative fuel consumption strategy over the past three minutes. That has left enough cryogenic fuel to fire nearly 90 seconds longer.

T+plus 4 minutes, 10 seconds. The 15-story tall starboard and port Common Booster Cores that provided the vast majority of thrust during the first four minutes of flight have expended their fuel and peeled away from the center stage. Tiny solid-fueled motors on the discarded boosters gave helpful nudges to ensure a clean separation. The boosters will tumble into the Atlantic Ocean below.

T+plus 4 minutes, 3 seconds. Engine cutoff! Standing by for booster separation.

T+plus 3 minutes, 35 seconds. Coming up in about 20 seconds, the outer Common Booster Cores will throttle down as a precursor to engine shutdown and jettison of the stages. It will take a few seconds to ease the power setting to half thrust. The boosters will operate at that throttle for another five seconds before the RS-68s are shut down.

T+plus 3 minutes. The center engine remains at 54.5 percent thrust while the starboard Common Booster Core's engines are firing at 108.5 percent. The outer boosters have just over one minute remaining in powered flight.

T+plus 2 minutes, 45 seconds. The Delta 4-Heavy now weighs half of what it did at liftoff. The rocket is burning vast amounts of cryogenic propellant to accelerate away from the planet.

T+plus 2 minutes. The 8-foot diameter bell-shaped nozzles on the three main engines gimbal during flight, allowing the rocket to steer itself on the intended trajectory eastward across the Atlantic Ocean and toward space.

T+plus 1 minute, 45 seconds. The outer Common Booster Cores and their RS-68 main engines continue to consume the supply of super-cold liquid hydrogen and liquid oxygen rocket fuel while firing at full throttle. The RS-68 is considered the world's largest hydrogen-fueled rocket engine.

T+plus 1 minute, 30 seconds. The vehicle is ascending through the flight regime that provides the maximum aerodynamic pressures on the rocket. This period is called Max-Q. And the Delta 4-Heavy is breaking the sound barrier as its speed reaches Mach 1.

T+plus 60 seconds. One minute into the flight of the Delta 4-Heavy. The rocket is slowly rising away from Earth with three distinct red-hot main engine plumes trailing 20 stories long, backdropped against the morning sky.

T+plus 40 seconds. The center Common Booster Core's main engine is throttling back to half thrust as a fuel conservation effort. The starboard and port boosters continue to operate at their maximum power setting.

T+plus 30 seconds. All three Aerojet Rocketdyne RS-68 main engines are firing at full throttle, gulping three tons of propellant per second to produce over two million pounds of thrust.

T+plus 15 seconds. The vehicle is beginning pitch and roll programs that will place the rocket on the proper heading to fly eastward from Cape Canaveral.

LIFTOFF! Liftoff of the first Orion capsule -- a new era of spaceflight begins!

T-minus 20 seconds. Green board.

T-minus 40 seconds. Upper stage liquid hydrogen tank now secure at flight level.

T-minus 55 seconds and counting. The Eastern Range has given its "go" for launch.

T-minus 60 seconds. The three RS-68 main engines are ready for ignition.

T-minus 80 seconds. The upper stage liquid oxygen tank is being verified at flight level.

T-minus 90 seconds and counting. All systems are "go" with a minute-and-a-half remaining in the countdown.

T-minus 1 minute, 40 seconds. The three Common Booster Core liquid hydrogen tanks have reached flight levels and pressures.

T-minus 2 minutes and counting. The rocket's upper stage liquid oxygen tank is being secured.

T-minus 2 minute, 30 seconds. The liquid oxygen tanks in the three Common Booster Cores are confirmed at the proper levels and pressures for flight.

T-minus 3 minutes and counting. Ordnance devices aboard the vehicle are being armed.

T-minus 3 minutes, 20 seconds. Replenishment of liquid hydrogen and liquid oxygen to the three Common Booster Cores is being secured in preparation to pressurize the tanks for launch.

T-minus 3 minutes, 50 seconds. The systems of the Common Booster Cores and upper stage of the Delta 4-Heavy rocket are switching from ground-fed power to internal batteries for launch.

T-minus 4 minutes and counting! Clocks are running again for launch of the Delta 4-Heavy rocket on the Exploration Flight Test 1. Liftoff is set to occur at 7:05 a.m. EST from pad 37B at Cape Canaveral Air Force Station, Florida.

Five minutes from launch at sunrise.

The launch director has granted his approval to resume the couontdown.

The launch team has been polled for readiness. All systems are reported GO.

Orion is going to internal power.

Lockheed Martin Mission Director Bryan Austin is GO.

Flight Director Mike Sarafin in Mission Control confirms Houston is GO.

Weather remains GO.

T-minus 4 minutes and holding. The countdown has just entered a planned hold point. Clocks will remain here for 15 minutes to give the launch team members a chance to finish any work running behind schedule and mission officials to conduct final readiness checks. Liftoff is still targeted for 7:05 a.m. EST.

Weather remains acceptable and winds have been within limits this morning.

Liquid hydrogen flight conditioning is reported complete.

T-minus 20 minutes. The countdown clocks will be going into a planned hold at the T-minus 4 minute mark. Liftoff remains targeted for 7:05 a.m. EST.

No issues are being reported with the Delta 4-Heavy rocket or Orion spacecraft.

Weather is now GO.

Checks of the rocket's safety system have been completed.

Upper stage LOX fill is complete. The vehicle is fully fueled for today's launch.

Two hours and counting! A check of the weather shows a RED condition currently for cumulus clouds.

Loading of the Common Booster Cores with liquid hydrogen has been accomplished this morning.

The upper stage has been loaded with liquid hydrogen.

Filling of liquid oxygen into the three Common Booster Cores is complete.

All weather rules are GO right now.

Fueling operations are progressing this morning at Complex 37. The Common Booster Cores are being loaded with liquid hydrogen and liquid oxygen. Chilldown conditioning of the upper stage.

United Launch Alliance has given approval to begin fueling the Delta 4-Heavy rocket this morning for the second attempt at flying Orion.

Yesterday's attempt was scrubbed by sluggish fill and drain valves on the launcher.

"Our team knows our rocket very, very well," said Dan Collins, chief operating officer of rocket-builder United Launch Alliance. "The team was absolutely on their game, listening to everything the rocket was telling us, and it ultimately told us it wasn't ready to go. And so we'll go make sure we've got a happy rocket and as soon as we do that, we're going to get back to the pad and send Orion off to a very, very successful test flight."

Today's launch window opens at 7:05 and closes at 9:44 a.m. EST.

The weather forecast calls for a 40 percent chance of acceptable conditions. The specifics include a broken deck of low clouds, showers in the vicinity, good visibility, northeasterly winds of 14 peaking to 21 knots and a temperature of 72 degrees.

"Our plan is to fly tomorrow," said Mark Geyer, NASA's Orion program manager.

The Delta 4-Heavy rocket and Orion will prepare to try again tomorrow to launch on the flight test around the Earth.

Liftoff was delayed from the original 7:05 a.m. by an errant boat in the restricted waters of the Atlantic, ground wind gusts above the limit and ultimately scrubbed by issues with fill and drain valves.

"We recommend we scrub today's operation based on issues we're working," a United launch Alliance Delta 4 manager told engineers. "So please set up for a 24-hour recycle."

The weather forecast for Friday calls for a 40 percent chance of acceptable conditions.

SCRUB!

NEW LAUNCH TIME is 9:44 a.m. pending resolution of the valve issue.

The count needs to pick up in 20 minutes to meet the end of today's launch opportunity.

Further troubleshooting is underway by slightly pressurizing the liquid hydrogen tanks of each Common Booster Core and cycling the fill and drain valves.

The cycle tests worked on the liquid oxygen valves. But the hydrogen valves on the port and core boosters are still being looked at.

Launch team members will be doing a series of cycle tests on all fill and drain valves of the Common Booster Cores.

The team is reporting alarms on two liquid oxygen fill and drain valves not reading fully closed.

HOLD at T-minus 3 minutes 9 seconds by a fill and drain valve not closed.

T-minus 3 minutes, 20 seconds. Replenishment of liquid hydrogen and liquid oxygen to the three Common Booster Cores is being secured in preparation to pressurize the tanks for launch.

T-minus 3 minutes, 50 seconds. The systems of the Common Booster Cores and upper stage of the Delta 4-Heavy rocket are switching from ground-fed power to internal batteries for launch.

T-minus 4 minutes and counting! Clocks are running again for launch of the Delta 4-Heavy rocket on the Exploration Flight Test 1. Liftoff is set to occur at 8:26 a.m. EST from pad 37B at Cape Canaveral Air Force Station, Florida.

The launch director has granted his approval to resume the couontdown.

The launch team has been polled for readiness again.

Orion is going back to internal power.

NEW LAUNCH TIME is 8:26 a.m.

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HOLD at T-minus 3 minutes 5 seconds by winds again.

T-minus 4 minutes and counting! Clocks are running again for launch of the Delta 4-Heavy rocket on the Exploration Flight Test 1. Liftoff is set to occur at 7:55 a.m. EST from pad 37B at Cape Canaveral Air Force Station, Florida.

The launch director has granted his approval to resume the couontdown.

The launch team has been polled for readiness again.

NEW LAUNCH TIME has been established for 7:55 a.m. EST after a wind gust above the launch limit.

The clock was stopped at T-minus 3 minutes and 43 seconds.

HOLD for ground winds!

T-minus 4 minutes and counting! Clocks are running again for launch of the Delta 4-Heavy rocket on the Exploration Flight Test 1. Liftoff is set to occur at 7:17 a.m. EST from pad 37B at Cape Canaveral Air Force Station, Florida.

Now five minutes from launch!

The final pre-flight poll of the launch team confirms all systems are "GO" for liftoff of the Delta 4-Heavy rocket and Orion this morning. The targeted launch time is 7:17 a.m. EST.

Readiness checks of the launch team is underway.

Orion has transferred to internal power.

America's heavy-lift rocket, the towering white and orange triple-barreled booster responsible for launching vital security and intelligence satellites, is ready to make another of its spectacular ascents from Cape Canaveral with Orion.

NEW LAUNCH TIME of 7:17 a.m.

Range is GO.

Liftoff officially delayed beyond 7:05 a.m.

HOLD EXTENDED by at least a few minutes to finish second stage propellant conditioning and the fouled Range by a boat.

The weather is observed and forecast "go" for launch.

NO GO for the Range has just been reported.

T-minus 4 minutes and holding. The countdown has just entered a planned hold point. Clocks will remain here for 15 minutes to give the launch team members a chance to finish any work running behind schedule and mission officials to conduct final readiness checks. Liftoff is still targeted for 7:05 a.m. EST.

T-minus 10 minutes. The countdown clocks will be going into a planned hold at the T-minus 4 minute mark. Liftoff remains targeted for 7:05 a.m. EST.

The latest update from the launch weather team still puts odds at a 70 percent chance of acceptable conditions for liftoff today. The potential areas of concern are thick clouds, ground winds and flight thru rain.

The official launch forecast calls for a few scattered clouds at 3,000 feet, a broken deck at 25,000 feet, 7 miles of visibility, a temperature in the 72 degrees F and northeasterly winds from 050 degrees at 13 peaking to 20 knots.

The countdown is entering the final 50 minutes until the Delta 4-Heavy rocket launch from Cape Canaveral at 7:05 a.m. EST. Here's a look at some stats about today's mission. This will be:

• The 369th Delta rocket launch since 1960
• The 28th Delta 4 rocket mission since 2002
• The 8th Heavy configuration to fly
• The 42nd-43rd-44th main engine from RS-68 family used
• he 454th production RL10 engine to be launched
• The 31st RL10B-2 engine launched
• The 23rd Delta 4 rocket launch from Cape Canaveral
• The 5th commercial use of Delta 4
• The 78th Evolved Expendable Launch Vehicle flight
• The 90th United Launch Alliance mission since 2006
• The 21st Delta 4 under the ULA banner
• The 5th launch of the Delta family in 2014
• The 1st Orion test flight

Steering checks of the Delta 4-Heavy rocket's engines have been conducted. The upper stage RL10 engine and the three Common Booster Core main engines were put through slew tests to confirm the rocket will be able to steer itself properly during ascent.

The Common Booster Cores have achieved liquid oxygen conditioning for flight.

Launch time continues aim for 7:05 a.m. EST, about five minutes after local sunrise. The rocket has been filled up with fuel for the mission. But as the countdown continues, all eight propellant tanks will be replenished to replace the cryogenics that naturally boil away.

Loading of the upper stage liquid oxygen tank is complete and the Delta 4-Heavy rocket now stands fully fueled for launch.

Now two hours and counting. Upper stage liquid hydrogen loading is complete.

Fueling of the three Common Booster Cores has been completed. The team has moved on to loading the upper stage with liquid hydrogen and liquid oxygen.

Approaching two-and-a-half hours and counting as the United Launch Alliance team works to get the Delta 4-Heavy rocket fully fueled with cryogenic propellants for today's launch. Liftoff remains scheduled for 7:05 a.m. EST. Weather is looking promising and there are no issues being reported in the count.

Weather continues to look just fine for the Delta 4-Heavy rocket's launch today. The outlook is calling for scattered low clouds and broken deck of high clouds, winds from northeast of 13 to 17 knots and temperatures in the 70s F with a 70 percent chance of meeting the launch weather rules.

Complex 37 has two giant sphere-shaped fuel tanks to store the cryogenic liquid oxygen and liquid hydrogen. The LOX tank holds 250,000 gallons and LH2 sphere about 850,000 gallons.

The cryogenics are fed from the storage tanks through pipelines to the pad. For the three Common Booster Cores, the propellants are routed up to the launch table upon which the rocket sits. Tail service masts, the large box-like structures at the base of the vehicle, feed the oxygen and hydrogen to the boosters via separate umbilicals. The upper stage receives its cryos from the middle swing arm that extends from the Fixed Umbilical Tower to the front-side of the rocket.

Fueling is scheduled to get underway at this time. It begins with the cold gas chilldown conditioning of the Common Booster Cores for liquid hydrogen loading.

The initial loading of liquid hydrogen propellant into the three Common Booster Core stages is a "slow-fill" mode that will be sped up to "fast-fill" after a small portion of each tank is loaded. Some 110,000 gallons of LH2 will be loaded into each tank.

Next, liquid oxygen chilldown will be completed. With the Common Booster Cores' liquid oxygen systems properly conditioned for cryogenic temperatures, the loading of Minus-298 degree LOX into the Delta 4-Heavy rocket will begin. Each tank will be loaded with about 40,000 gallons of supercold LOX.

Chilled to Minus-423 degrees Fahrenheit, the liquid hydrogen will be consumed by the RS-68 main engines along with liquid oxygen during the early minutes of launch.

T-minus 4 hours 15 minutes and holding. The countdown has entered a 15-minute hold prior to the start of fueling.

The 330-foot tall mobile service tower has been retracted from the Delta 4-Heavy rocket at Cape Canaveral's pad 37B for tomorrow morning's launch that will place the Orion spacecraft on its intended trajectory.

The wheeled gantry structure just moved along rail tracks to its launch position about the length of a football field away from the Delta 4 rocket. The 9-million pound tower shielded the Delta from the elements during the its stay on the pad, provided workers 360-degree access to the various areas on the vehicle and was used to attach the payload during the launch campaign. The tower is 90-feet wide and 40-feet deep.

Crews will spend the next couple of hours securing the complex for launch before leaving the danger area around the pad. All workers must be clear of the area for the start of hazardous operations in the countdown, which include fueling the Delta 4's Common Booster Cores and the second stage with supercold liquid oxygen and liquid hydrogen propellants.

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

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

Liftoff remains scheduled for 7:05 a.m. EST (1205 GMT).

Rollback of the mobile service tower at Complex 37 to uncover the Delta 4-Heavy rocket is underway.

T-minus 9 hours 30 minutes and counting. The countdown has commenced for tomorrow's launch of the Delta 4-Heavy rocket. With 30 minutes of planned hold time built into the count, liftoff remains set for 7:05 a.m. EST (1205 GMT).

Weather forecasters are calling for a 70 percent chance of favorable conditions for the launch Thursday morning.

"Things are starting to look real promising for tomorrow," said launch weather officer Kathy Winters.

"On the vehicle side, everything is extremely clean," said Mark Geyer, NASA's Orion program manager. "We're go, we're ready to go."

Meanwhile, the mood in Mission Control in Houston is upbeat heading into the countdown.

"We haven't had this feeling in a while, since the end of the shuttle program, launching an American spacecraft from American soil and beginning something new, in this case exploring deep space," said Orion Flight Director Mike Serafin. "It's a new mission and there are some things I'm sure we're going to learn tomorrow from this unmanned flight test that will enable us to fly humans into deep space."

"This test flight is a big, big deal because it's going to give us an opportunity to demonstrate three big things about the vehicle," NASA Administrator Charles Bolden told CBS News. "One, that it is capable of withstanding the temperatures and pressures of re-entry, so we're looking at the heat shield and the structure itself.

"We're looking for how (the spacecraft) performs on orbit, both (under) commands from the ground and autonomously while it's doing things it's programmed to do with its guidance and navigation system. And finally, once it makes its deorbit and gets through the atmosphere and it's time to decelerate, are the parachutes going to work? We think they are, we're confident they are, but the proof is in the pudding."

T-minus 1 day and counting to arguably NASA's biggest launch since the space shuttles were retired.

"It's a big deal. This is the first human-rated spacecraft that's gone beyond (low-Earth orbit) in 42 years," said Mike Hawes, Lockheed Martin's Orion program manager.

The Orion spacecraft, NASA's new deep space exploration vehicle, is going on its first unpiloted flight test to check systems at the heart of the ship -- the crew module.

"Orion is built to go beyond low-Earth orbit. It's an exploration spacecraft," said Mark Geyer, NASA's Orion program manager.

"In concert with the Space Launch System, which gets us to those destinations, we're ging to be able to explore the regions around the Moon and then out into the solar system, including Mars. Thursday is the beginning of that journey, testing key systems, the riskiest systems before we have any people on it."

Liftoff is planned for Thursday at 7:05 a.m. EST, sunrise on the Florida's Space Coast. The available window extends to 9:44 a.m. EST.

"We are on a Delta 4-Heavy. This is a great rocket for this test. It gets us to the high altitude and the velocity we need to test the heat shield, which is the primary objective of the test. It's a beautiful rocket and it'll be a lot of fun on Thursday to see it go," said Geyer.

The Launch Readiness Review has been passed for Thursday's Delta 4-Heavy rocket of NASA's first space-worthy Orion capsule.

Officials gathered this morning and gave approval to enter into the countdown at Complex 37 Wednesday evening.

"We looked at our launch vehicle, making sure it it is ready, along with the spacecraft and Range assets. We are ready to go," said Ron Fortson, ULA's director of mission management.

Clocks will begin ticking at 9:05 p.m. EST and retraction of the mobile service gantry will occur at 11:05 p.m. Orion gets powered up at 1:05 a.m. Fueling will commence at 2:35 a.m.

The launch is planned for 7:05 a.m. EST. The available launch window extends to 9:44 a.m. EST.

Orion will fly in Earth orbit for two revolutions, going as high as 3,600 miles for an unpiloted test flight before re-entering and splashing down in the Pacific Ocean.

The weather outlook for launch from Cape Canaveral continues to call for 60 percent chance of acceptable conditions.

"A high pressure ridge extends from the Atlantic through Georgia, and another area of high pressure is moving into the Great Lakes area. The high pressure area moving into the Great Lakes region will continue to migrate east and into the Atlantic by Thursday morning," Air Force meteorologists report.

"With these high pressure areas to the north, gusty easterly winds will persist this week over the Florida East Coast. Low level moisture will cause low clouds and occasional coastal showers to move in from offshore all week, particularly during the morning hours.

"On the morning of launch, these clouds and showers are not expected to extend above the freezing level; therefore, coastal showers and gusty winds are the main concern."

The specifics for the launch opportunity include broken decks of low- and mid-level clouds, good visibility, winds from the northeast at 12 gusting to 17 knots and a temperature of 72 degrees.

Weather forecasters will watch for isolated rain showers and gusty winds that could delay Thursday's launch of a Delta 4-Heavy rocket carrying NASA's Orion space capsule on its first flight into orbit.

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