SpaceX did its best Wednesday to quiet critics and convince NASA the company is ready to deliver supplies to the International Space Station some time next year.

Read our full story.

Check out pictures of today's blastoff from remote cameras at Complex 40. We have also posted a photo gallery documenting the Dragon's splashdown in the Pacific Ocean.

Gwynne Shotwell, SpaceX president, says the Dragon spacecraft may have landed within as little as 800 meters, or about one-half of a mile, within its splashdown aimpoint. The descent velocity under the main parachutes was about 18 mph, Shotwell said in a press briefing.

SpaceX and NASA officials are heralding today's mission as a flawless flight.

Watch a video clip of today's Falcon 9 launch from Florida.

The Dragon's performance on-orbit was 100 percent successful, according to SpaceX.

The recovery crew in the Pacific Ocean has already arrived at the capsule and attached flotation devices to the spacecraft.

A SpaceX spokesperson says the Dragon also landed on target in the Pacific Ocean.

NASA is planning a post-flight press conference as soon as 3:30 p.m. EST (2030 GMT) to discuss further details of the mission.

The Dragon spacecraft made a soft landing, according to SpaceX.

SPLASHDOWN. SpaceX confirms the Dragon spacecraft has landed.

PARACHUTES DEPLOYED. All three 116-foot-diameter main parachutes have been deployed on the Dragon capsule, according to SpaceX.

Dragon should be falling through the atmosphere right now, with temperatures outside the spacecraft reaching more than 3,000 degrees Fahrenheit.

SpaceX is managing two simultaneous recovery operations off both coasts of the United States this afternoon. NASA's shuttle solid rocket booster retrieval ships are stationed several hundred miles off the coast of Cape Hatteras, N.C., in an attempt to pick up the Falcon 9 rocket's first stage, which is designed to return to Earth intact.

Another group of recovery personnel are located in the Pacific Ocean 500 miles west of northern Mexico to retrieve the Dragon capsule.

Dragon has maneuvered to the correct attitude for re-entry. The spacecraft plunges back into the atmosphere with its heat shield facing in the direction of travel.

The spacecraft should encounter the first traces of Earth's atmosphere in about 15 minutes.

DE-ORBIT BURN COMPLETE. SpaceX reports the burn was nominal.

DE-ORBIT BURN UNDERWAY. Four Draco thrusters are firing to slow the Dragon spacecraft's velocity to fall from orbit.

The de-orbit burn will be conducted by a subset of the Dragon's 18 Draco maneuvering thrusters, which each produce about 90 pounds of thrust. The firing will slow the craft's speed and lower its orbit enough to be captured by Earth's atmosphere.

Splashdown of the Dragon is scheduled for a little after 2 p.m. EST (1900 GMT) in the Pacific Ocean about 500 miles west of northern Mexico.

The Dragon's de-orbit burn is expected to begin in 15 or 20 minutes, according to a SpaceX spokesperson.

Spaceflight Now's Justin Ray was at the NASA Causeway for this morning's launch. He has posted his spectacular launch photos.

A reminder 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.)

Recovery teams in the Atlantic Ocean have telemetry and radar on the Falcon 9 rocket's first stage, according to SpaceX.

Meanwhile, the company confirms a cache of secondary U.S. government CubeSat payloads have separated from the rocket.

"Dragon is performing nominally," says Kirsten Brost, SpaceX spokesperson. The ongoing tests are supposed to be automated, but ground controllers will manually command the de-orbit burn at 1:15 p.m. EST (1815 GMT) if things look good after two orbits.

SpaceX spokesperson Kirstin Brost says the company has a lock with the spacecraft through NASA tracking and data relay satellites and the spacecraft is firing.

SpaceX reports they will provide updates as possible during the Dragon's test flight, which is supposed to last two or three orbits. A post-mission press conference is planned for about an hour or two after splashdown in the Pacific Ocean.

According to the timeline SpaceX released before the mission, Dragon will land 3 hours, 19 minutes after launch if the flight lasts the standard two orbits. That puts landing at 2:02 p.m. EST (1902 GMT).

SpaceX reports the Falcon 9 rocket achieved an orbit with a low point of 288 kilometers, a high point of about 301 kilometers and an inclination of 34.53 degrees.

All those parameters are close to the targeted marks, which called for a near-circular orbit 300 kilometers high with an inclination of 34.5 degrees.

DRAGON SEPARATION!

T+plus 9 minutes, 15 seconds. Second stage engine cutoff.

T+plus 8 minutes. One minute until the second stage Merlin engine is supposed to shut down as the vehicle reaches orbit. The rocket is aiming for a 186-mile-high orbit with an inclination of 34.5 degrees.

T+plus 8 minutes. One minute until the second stage Merlin engine is supposed to shut down as the vehicle reaches orbit. The rocket is aiming for a 186-mile-high orbit with an inclination of 34.5 degrees.

T+plus 6 minutes. No problems with the launch so far. The second stage is stable and a rocketcam is returning live video from the rocket.

T+plus 4 minutes, 50 seconds. Altitude is 210 kilometers and a ground station in New Hampshire has acquired signals from the rocket.

T+plus 4 minutes. The Dragon's nose cone has been jettisoned, and SpaceX reports the Merlin vacuum engine is firing well.

T+plus 3 minutes, 15 seconds. The Falcon 9 first stage engines have cut off, the stages have separated, and the rocket's second stage Merlin vacuum engine has ignited for its nearly six-minute firing to reach orbital velocity.

T+plus 2 minutes. Now soaring at an altitude of more than 20 miles, the Falcon 9 rocket's first stage will shut down and jettison in about one minute. Two engines will be turned off first, followed a few moments later by the remaining seven engines.

T+plus 1 minute. The Falcon 9 rocket is approaching the speed of sound and the phase of maximum aerodynamic pressure.

LIFTOFF! The Falcon 9 rocket is soaring away from Cape Canaveral, heralding a new era in commercial spaceflight.

T-minus 1 minute and counting. In the final minute of the countdown, the flight computer will command checks of the first stage Merlin engine steering system and the Falcon 9 propellant tanks will be pressurized for flight.

Thousands of gallons of water will also be dumped onto the launch pad deck to suppress the sound and acoustics of liftoff.

The command to start the ignition sequence for the first stage will be issued at T-minus 3 seconds, triggering the Merlin engines' TEA-TEB ignitor source moments before the powerplants actually ramp up to full power.

T-minus 2 minutes and counting. The SpaceX launch director and the Air Force Eastern Range have given their final approvals for liftoff of the Falcon 9 rocket at 10:43 a.m. EST (1543 GMT).

T-minus 3 minutes and counting. The rocket's destruct system is on internal power and being armed, the ground TEA-TEB first ignition system is ready for launch, and liquid oxygen topping is being terminated.

T-minus 4 minutes and counting. Both stages of the Falcon 9 rocket are now running on internal power. And the Dragon spacecraft is now running off of its flight battery.

T-minus 5 minutes and counting. The Falcon 9 computer is aligned for flight. The automated sequence is now terminating loading of gaseous nitrogen into the second stage attitude control system.

T-minus 6 minutes and counting. The Falcon 9 computer and navigation system is configuring for flight and all nine Merlin engine pumps on the first stage are chilled down.

T-minus 7 minutes and counting. Within the next minute, the Falcon 9's flight computer will be commanded to its alignment state. The Merlin engine pumps are continuing to chill down.

T-minus 9 minutes and counting. Prevalves leading to the Falcon 9's Merlin first stage engines are opening, permitting super-cold liquid oxygen to flow into the engines to condition them for ignition.

T-minus 10 minutes and counting. The terminal countdown autosequence has started. Any hold after this point will result in an automatic abort.

T-minus 13 minutes and counting. The countdown has resumed as SpaceX targets another launch opportunity at 10:43 a.m. EST (1543 GMT). The launch team is now being polled for readiness to enter the terminal countdown.

The countdown clock will resume in 10 minutes at T-minus 13 minutes and counting. Winds aloft and on the ground are observed "go" for launch, and the Air Force range reports they are "go" for launch.

The launch conductor reports the 10:43 a.m. EST (1543 GMT) launch time has been approved.

Keep track of the Falcon 9's milestones during flight! Check out this timeline of the launch sequence provided by SpaceX.

The launch times this morning are based on the availability of NASA's Tracking and Data Relay Satellite System, a network of communications spacecraft that provide communications links between space assets and ground controllers.

A reminder 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.)

One hour until the next launch attempt this morning.

SpaceX says there was a false abort due to an issue with the ordnance interrupter ground feedback position in the terminal countdown. The issues is resolved and the launch team is setting up for another attempt at 10:43 a.m. EST (1543 GMT).

NEW LAUNCH TIME. SpaceX is targeting 10:42 a.m. EST (1542 GMT) for the next launch opportunity this morning, assuming engineers can resolve whatever caused the abort earlier today.

The countdown clock will recycle to T-minus 13 minutes and holding as engineers evaluate the cause and solution for this issue.

The countdown was stopped at T-minus 2 minutes, 48 seconds. This hold means the earliest the rocket could blast off is 10:38 a.m. EST (1538 GMT). That is the next opportunity this morning.

HOLD. The countdown is holding and the SpaceX launch team is safing the vehicle. Launch will not occur at 9:06 a.m. EST, but we don't know what caused the unplanned hold.

T-minus 3 minutes and counting. The rocket's destruct system is on internal power and being armed, the ground TEA-TEB first ignition system is ready for launch, and liquid oxygen topping is being terminated.

T-minus 4 minutes and counting. Both stages of the Falcon 9 rocket are now running on internal power.

T-minus 5 minutes and counting. The Falcon 9 computer is aligned for flight and all nine Merlin engines are chilled down for ignition.

The automated sequence is now terminating loading of gaseous nitrogen into the second stage attitude control system.

T-minus 6 minutes and counting. The Falcon 9 computer and navigation system is configuring for flight.

T-minus 7 minutes and counting. Within the next minute, the Falcon 9's flight computer will be commanded to its alignment state. The Merlin engine pumps are continuing to chill down.

T-minus 9 minutes and counting. Prevalves have been opened leading the Falcon 9's nine first stage engine to permit super-cold liquid oxygen to flow into the pumps. This activity helps condition the engines for ignition.

T-minus 10 minutes and counting. The countdown has entered the terminal phase.

T-minus 12 minutes and counting. A poll of the launch team concluded with a "go" to enter the terminal countdown at T-minus 10 minutes.

T-minus 14 minutes and counting. The launch director will soon poll the SpaceX team for a "go" to enter the terminal countdown at T-minus 10 minutes.

T-minus 16 minutes and counting. Weather is expected to be favorable for the first two launch window panes this morning. The launch team has completed steering checks of the second stage thrust vector control system.

T-minus 21 minutes and counting. Flight hazard roadblocks have been established at Cape Canaveral.

T-minus 25 minutes and counting. Flight termination system checks have been completed.

SpaceX reports the Falcon 9 rocket is fully fueled for launch. Both stages consume refined kerosene and liquid oxygen propellants.

Weather is looking favorable for liftoff at 9:06 a.m. EST. The three-minute delay was due to a collision avoidance cutout to avoid flying too close to the International Space Station.

T-minus 40 minutes and counting. We haven't received any reports of problems in the countdown so far. We are awaiting the beginning of SpaceX's webcast of the launch.

SpaceX workers have packed the Dragon capsule with memorabilia to commemorate today's flight.

"There's all sorts of memorabilia," said Elon Musk, founder and CEO of SpaceX. "There are badges for everyone at the company, so everyone has a badge that's been in space. Then there are a lot of knick-knacks and odds and ends, then there's a humorous secret payload that I can't tell you about."

"If the mission's successful, I'll tell you about it," Musk said. "Otherwise, I won't."

Weather is currently observed "red" for first stage recovery, but the impact of this observation is unclear. All other weather parameters are "green" and forecasters continue to predict just a 10 percent chance of conditions violating launch criteria.

SpaceX is leasing the ships normally used to retrieve space shuttle solid rocket boosters in an attempt to recover the Falcon 9's first stage in the Atlantic Ocean a few hundred miles off the coast of Cape Hatteras, N.C.

There is a 30 percent chance of weather prohibiting launch Thursday and a 10 percent chance of unacceptable conditions Friday.

SpaceX spokesperson Kirstin Brost has provided more information on the cause of the engine nozzle cracks that triggered the Falcon 9 launch delay from Tuesday.

"SpaceX has discovered the root cause of the two small cracks in the aft end of the 2nd stage engine nozzle extension," the statement said. "A GN2 vent line caused fluttering of the the thinnest portion of the nozzle extension, creating the cracks. SpaceX engineers repaired the extension by trimming off the end where the cracks are located and corrected the root cause by diffusing the vent."

NEW LAUNCH TIME. Liftoff is now being targeted for 9:06 a.m. EST (1406 GMT).

If liftoff does not occur at 9:06 a.m. EST, the next opportunity to launch is at about 10:38 a.m. EST. SpaceX has three short launch windows within today's nearly three-and-a-half hour period that ends at 12:22 p.m. EST.

The strongback umbilical tower is now beginning to retract at Complex 40. The structure moves about 15 degrees away from the Falcon 9 rocket to permit propellant loading into the vehicle's second stage.

The liquid oxygen is stored in a 125,000-gallon sphere in the southeast quadrant of Complex 40. The rocket's RP-1 kerosene fuel is kept in cylinder-shaped tanks on the west side of the pad.

Engineers plan to load nearly 39,000 gallons of super cold liquid oxygen and almost 25,000 gallons of kerosene fuel into the first stage tanks. About 7,300 gallons of liquid oxygen and 4,600 gallons of kerosene will go into the second stage.

The propellants flow into the first stage through the launch mount at the base of the rocket. Kerosene and liquid oxygen will be pumped up the strongback umbilical tower to enter the second stage.

A few dozen engineers and managers are stationed inside the SpaceX Launch Control Center near the south gate to Cape Canaveral Air Force Station.

A reminder 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.)

For a thorough overview of what's going on in the Falcon 9 countdown, refer to a timeline provided by SpaceX.

Fueling of the Falcon 9 rocket is underway, according to NASA.

T-minus 2 hours, 33 minutes and counting. Countdown clocks are ticking down to a scheduled launch time of 9:03 a.m. EST (1403 GMT) this morning.

It is a cold and breezy, but clear, morning at Cape Canaveral.

After trimming away a cracked portion of an engine nozzle, SpaceX is readying its Falcon 9 rocket for a launch opportunity this morning.

The launch window opens at 9 a.m. EST (1400 GMT), but SpaceX will likely target liftoff three minutes later at 9:03 a.m. EST (1403 GMT). If the Falcon 9 rocket can't get off the ground by 12:22 p.m. EST (1722 GMT), the launch will be put off until Thursday.

The mission was originally scheduled for Tuesday, but SpaceX discovered two small cracks in the niobium alloy nozzle extension on the Falcon 9's second stage Merlin engine.

SpaceX said the nozzle extension, which is about twice the thickness of a soda can, is not necessary to achieve all the performance necessary on this launch. The extension makes the Merlin engine burn more efficiently in the vacuum of space.

Technicians working on a cherry-picker crane cut away the suspect portion of the nozzle, and inspections continued late Tuesday night.

If SpaceX is on track for the 9:03 a.m. launch opportunity, fueling operations are expected to begin after 7 a.m. EST (1200 GMT) today.

Wednesday's twice-around-the-world test flight of SpaceX's Dragon spacecraft is fraught with risk, and the company's wealthy founder and chief executive predicts about a 60 percent chance the mission meets all of its objectives.

Read our full story.

View the Falcon 9 rocket in our photos taken at and around Complex 40 today.

SpaceX says everything still looks good for a launch attempt Wednesday morning.

"SpaceX engineers are currently performing their final inspections before launch," a company spokesperson just reported. "So far everything looks good, but we won't have the final all-clear until around 9 p.m. EST."

GO FOR LAUNCH. Officials have approved plans to launch the Falcon 9 rocket tomorrow morning. The launch window opens at 9 a.m. EST and closes at 12:22 p.m. EST (1400-1722 GMT).

We are expecting an announcement shortly on a potential launch attempt tomorrow.

Weather forecasters are projecting an 80 percent chance of favorable conditions for the Falcon 9 rocket's potential launch attempt on Wednesday.

"Although Wednesday may start out clear, an upper level trough will produce increasing mid and upper level clouds through the day. The timing of these clouds' arrival will be critical since by afternoon they will likely violate range safety rules," the Air Force weather team says.

The specifics include a few-to-scattered clouds at 12,000 feet, scattered-to-broken clouds at 20,000 feet, good visibility, northwesterly winds of 10 gusting to 15 knots and a temperature between 47 and 55 degrees F during the launch window.

The outlook for Thursday's backup launch opportunity is 90 percent favorable. Meteorologists say the cloud cover should be moving out the area with the trough and pose less of a concern.

According to a SpaceX statement just released, the company is still analyzing two cracks on the niobium alloy extension of the Falcon 9 rocket's second stage engine nozzle.

"These cracks are in a region near the end of the nozzle extension where there is very little stress and so they would not cause a flight failure by themselves," the statement said. "However, further investigation is warranted to ensure that these cracks are not symptomatic of a more serious problem."

SpaceX expects to announce this evening whether they will launch the rocket Wednesday.

SpaceX has released more details on the cracks found on the niobium nozzle of the Falcon 9 rocket's second stage Merlin engine. Here is the latest statement from the company:

"SpaceX engineers are analyzing two small cracks in the aft end of the 2nd stage engine nozzle extension. These cracks are in a region near the end of the nozzle extension where there is very little stress and so they would not cause a flight failure by themselves. However, further investigation is warranted to ensure that these cracks are not symptomatic of a more serious problem.

A decision on whether or not to attempt launch on Wednesday will be provided tomorrow evening.

The bell shaped Merlin Vacuum nozzle extension is made of niobium sheet alloy, measures 9 feet tall and 8 feet at the base diameter, and thins out to about twice the thickness of a soda can at the end. Although made of an exotic refractory alloy metal with a melting temperature high enough to boil steel, this component is geometrically the simplest part of the engine.

It is important to note that the niobium nozzle extension increases the efficiency of the Merlin engine in vacuum and is installed by default on all upper stage Merlin engines, but that efficiency increase is not required for this mission. The nozzle extension is most helpful when launching very heavy satellites or to maximize throw mass to distant destinations like Mars. The most likely path forward is that we will trim off the thinnest portion of the nozzle extension, which is where the cracks are located, perform a thorough systems check and resume launch preparation."

Check out our collection of photos of the Falcon 9 rocket on the launch pad today.

Analysis of two small cracks on the aft end of the second stage engine nozzle continues, according to SpaceX. A decision on a launch date is not expected until Tuesday.

NASA just issued the following statement:

"A demonstration launch of SpaceX's Falcon 9 rocket for NASA's Commercial Orbital Transportation Services program has been rescheduled for no earlier than Wednesday, Dec. 8. The delay is because of a crack in the engine nozzle on the rocket's second stage.

During a routine review of close-out photos of the rocket on Monday, SpaceX engineers discovered the crack, which measures about three inches long. Preparations continue on the rocket at Cape Canaveral Air Force Station's Launch Complex 40 in Florida.

SpaceX is considering several options, including repairing the crack or shipping a replacement part from California. More information on the launch schedule will be announced when available."

More details on the next launch opportunity for the Falcon 9 rocket aren't likely until Tuesday morning.

You can download the SpaceX press kit to get details of the Falcon 9 and Dragon flight objectives.

Inspections of the second stage engine's 9-foot-long nozzle continue at Complex 40. A SpaceX spokesperson says liftoff Wednesday is "possible, but not probable."

Officials aren't sure if they will know tonight whether launch will be targeted for Wednesday or Thursday. If managers elect to change second stage engine nozzles, liftoff would be pushed by to at least Friday.

NASA says launch could occur as soon as Wednesday now, but they expect more details this afternoon.

In an ongoing press conference at Kennedy Space Center, SpaceX reports engineers discovered porosity and potential cracking in a weld joint in the Falcon 9 rocket's second stage Merlin engine.

The upper stage engine includes an expansion nozzle specially designed for firing in the vacuum of space. The nozzle is made of a lightweight but sturdy niobium material.

The rocket was lowered horizontally this morning for inspections. The rocket is now vertical again as engineers exercise the upper stage's thrust vector control steering system in another test of the engine, according to Gwynne Shotwell, president of SpaceX.

LAUNCH DELAY. Liftoff of the Falcon 9 rocket has been postponed to at least Thursday, Dec. 9, SpaceX just announced.

Gwynne Shotwell, SpaceX president, said engineers found an issue with the Falcon 9 rocket's second stage engines in a review of closeout photos this morning.

"It looks like the first attempt of this flight is no earlier than Thursday, if things look good," Shotwell said.

If a new niobium vacuum nozzle is required on the second stage Merlin engine, launch could be pushed back to Friday or Saturday, Shotwell said.

Today and Monday will mostly be spent reviewing data from Saturday's static fire test of the Falcon 9 rocket's nine main engines, according to Elon Musk, founder and CEO of SpaceX.

"It's just data review," Musk said in an interview Sunday afternoon. "Generally we want to have a few days between static fire and launch in order to properly digest the data."

Teams are also activating the rocket's flight termination system, a destruct mechanism that would be used to end the launch if it threatened populated areas. Technicians are also doing final closeouts on the rocket and putting the vehicle in flight configuration, Musk said.

"But mostly it's just about an exhaustive repeated review of the data to find any clue that there could be an issue with launch," Musk said.

Liftoff remains set for a launch window opening at 9 a.m. and closing at 12:22 p.m. EST (1400-1722 GMT) Tuesday.

Air Force meteorologists are predicting frigid and windy weather for Tuesday's planned launch of the Falcon 9 rocket from Cape Canaveral.

"A cold front is pushing through central Florida from the northeast resulting in an increase in clouds and a reinforcing shot of cold air. Late Monday and into Tuesday, a strong surge of wind is forecast to bring more cold air into the area, dropping low temperatures Tuesday morning into the mid 30s. If this wind surge lasts into Tuesday's launch window, winds will be a concern for violating liftoff constraints," the launch weather team reports.

Those strong winds equate to forecasters giving only a 40 percent chance of weather allowing the Falcon to fly during Tuesday's 9 a.m. to 12:22 p.m. EST launch window.

The launch outlook calls for scattered low clouds at 2,500 feet, good visibility, northwesterly winds of 20 peaking to 25 knots and a temperature between 42 and 45 degrees F.

The forecast for backup launch opportunities on Wednesday and Thursday improves to 90 percent favorable both days. A stray rain shower moving ashore from the Atlantic will be the only concern.

"Wind should remain northwesterly with lower speeds Wednesday and Thursday, allowing clear, dry weather to continue while reducing the liftoff wind threat. If the winds veer onshore, clouds or isolated rain showers are possible, which may result in a violation of the flight through precipitation rule," meteorologists say.

Accomplishing a crucial test before its scheduled launch next week, SpaceX's Falcon 9 rocket fired nine main engines for three-and-a-half seconds Saturday morning, briefly ramping up to nearly a million pounds of thrust while the booster was firmly held to the ground.

SpaceX just posted an update on their Twitter account:

"Full duration static fire! We'll continue to review data, but today's static fire appears to be a success."

The strongback fueling tower has moved back against the Falcon 9 rocket at Complex 40.

SpaceX's audio and video feed has ended for now, so we don't know whether today's static fire met all the planned objectives, including the planned 2 second duration at full thrust.

It is unclear when the company might release further information.

Officials are reviewing data to determine whether this engine firing met all criteria for today's test.

IGNITION. The Falcon 9's Merlin first stage engines appeared to ignite with a flash of orange flame at the launch pad. We are standing by for word from SpaceX.

T-minus 1 minute and counting. Standing by for pressurization of the Falcon 9's propellant tanks for this 3.5-second engine firing.

T-minus 2 minutes and counting. The Air Force Eastern Range is go for the test, helium loading is terminated and main engine purges have been set for ignition.

The webcast has resumed at T-minus 3 minutes and everything continues to go well. Liquid oxygen loading has been terminated as planned and the launch director has given final approval for today's test.

SpaceX's webcast has stopped and we are not receiving live updates of the countdown.

T-minus 6 minutes and counting. The first stage engines are chilled in for ignition, the first stage fuel bleed sequence has started and the navigation system is configuring for flight.

T-minus 9 minutes and counting. Chilldown of the first stage's nine Merlin engines is underway.

T-minus 10 minutes and counting. The terminal countdown has started.

T-minus 12 minutes and counting. A poll of the launch team concluded with a "go" to initiate the terminal countdown.

T-minus 13 minutes and counting. The clocks have resumed ticking forward a static fire attempt at 10:50 a.m. EST (1550 GMT).

The abort at 9:30 a.m. EST was due to low pressure in the gas generator of Engine No. 6, the same engine that triggered yesterday's abort.

Now SpaceX says 10:50 a.m. EST (1550 GMT) is the earliest they can be ready to support another engine firing. Engineers are reconfiguring the Falcon 9's flight computer right now.

The launch director just reported a preliminary target time for another static fire attempt at 10:30 a.m. EST (1530 GMT).

The countdown is now recycled to T-minus 13 minutes and holding as officials assess the situation.

SpaceX reports the countdown was aborted at T-minus 1.9 seconds and officials are reviewing data in hopes of staging another attempt later today.

The countdown will be recycled to T-minus 13 minutes to set up for another possible static fire attempt today. The available window extends until 3 p.m. EST (2000 GMT).

The launch team is safing the rocket while determining the cause and a potential solution for the abort.

ABORT.

T-minus 1 minute and counting. Propellant tanks will soon pressurize for ignition.

T-minus 2 minutes and counting. The launch director has given a "go" for today's static fire.

T-minus 3 minutes and counting. The launch team is configuring the first stage's TEA-TEB ignitor system and has stopped loading liquid oxygen into the rocket in preparation for ignition.

T-minus 5 minutes and counting. The launch vehicle is being transitioned to internal power.

T-minus 6 minutes and counting. The first stage fuel bleed cycle is underway and the navigation system is being aligned for flight.

T-minus 8 minutes and counting. The pumps of the Falcon's nine Merlin first stage engines are being conditioned for ignition.

T-minus 10 minutes and counting. The countdown has entered the terminal phase.

T-minus 12 minutes and counting. The launch director has given approval to enter the terminal countdown at T-minus 10 minutes.

T-minus 13 minutes and counting. Managers are polling the launch team to verify their readiness to enter the terminal countdown.

T-minus 20 minutes and counting. The Falcon 9 rocket's nine Merlin first stage engines will be ignited today for 3.5 seconds, enough time to verify systems on the ground and the launch vehicle responsible for the final few seconds of the countdown. The engines will be at full power for approximately 2 seconds.

The engines will produce nearly 1 million pounds of total sea level thrust, more than four times the power of a 747 jumbo jet at full throttle. The engines consume about 3,200 pounds of kerosene and liquid oxygen propellants per second, according to SpaceX.

Yesterday's static fire attempt was automatically aborted at T-minus 1.1 seconds by a high chamber pressure reading in Engine No. 6. SpaceX has not said how engineers resolved the issue.

The first stage liquid oxygen loading is about to transition to topping mode, ending the fueling process for the two-stage Falcon 9 rocket. Kerosene fuel is already loaded on-board and the second stage liquid oxygen tank was filled a few minutes ago.

SpaceX reports the first stage liquid oxygen tank is approximately 88 percent full. Helium pressurant has been loaded into the first stage.

Liquid oxygen loading of the Falcon 9 rocket is nearing completion. Both stages of the rocket are powered by Merlin engines burning refined kerosene fuel and liquid oxygen.

The liquid oxygen is stored in a 125,000-gallon sphere in the southeast quadrant of Complex 40. The rocket's RP-1 kerosene fuel is kept in cylinder-shaped tanks on the west side of the pad.

Engineers plan to load nearly 39,000 gallons of super cold liquid oxygen and almost 25,000 gallons of kerosene fuel into the first stage tanks. About 7,300 gallons of liquid oxygen and around 4,600 gallons of kerosene will go into the second stage.

The propellants flow into the first stage through the launch mount at the base of the rocket. Kerosene and liquid oxygen will be pumped up the strongback umbilical tower to enter the second stage.

The strongback umbilical tower has retracted about 15 degrees away from the Falcon 9 rocket and fueling preparations are underway at Complex 40. SpaceX reports the static fire test could occur as soon as 9:30 a.m. EST (1430 GMT).

SpaceX has between 9 a.m. and 3 p.m. EST (1400-2000 GMT) today for this preflight engine firing. The company says it plans another webcast for today's attempt, but it has released no details on when the launch team could actually target ignition.

SpaceX has issued a statement following today's aborted engine test:

"Today the 1st static fire attempt aborted at T-1.1 seconds due to high engine chamber pressure. We are reviewing data now and will make a second attempt tomorrow. Thanks for watching!"

The strongback has moved back in place against the Falcon 9 rocket for detanking and safing procedures.

SCRUB. Today's Falcon 9 static engine firing has been scrubbed until at least tomorrow. We are standing by for further information from SpaceX.

Officials are evaluating whether to make a second attempt at the Falcon 9 static fire today.

The 1 p.m. EST static fire attempt was actually aborted before attaining the required 2 second burn at full thrust. SpaceX may try again this afternoon at 3 p.m. EST (2000 GMT), but the company has not said whether the launch team will actually make another attempt today.

The abort was ordered at T-minus 1.1 seconds due to a high chamber pressure in Engine No. 6.

Officials have programmed tight limits into the countdown and engine start sequence, and minor temperature and pressure issues can trigger an automatic abort.

A statement is expected from SpaceX this afternoon regarding the outcome of today's static fire and plans for a potential launch attempt Tuesday.

Liftoff is scheduled for a launch window opening at 9 a.m. EST (1400 GMT) and closing at 12:21 p.m. EST (1721 GMT).

SpaceX reports the test sequence is complete.

IGNITION. The Falcon 9 rocket's nine Merlin engines have fired for a brief test at Complex 40.

T-minus 1 minute and counting. The Falcon 9 rocket's propellant tanks are being pressurized in the final minute of the countdown. The Air Force Eastern Range just gave their final approval for the test.

T-minus 4 minutes and counting. The Merlin engine pumps are being chilled in preparation their brief firing, sending a plume of vapors from the bottom of the rocket.

T-minus 8 minutes and counting. All stations report they are ready for the terminal count and static engine test.

T-minus 10 minutes and counting. The countdown has resumed and the launch team is hoping to conduct the Falcon 9 static test firing at 1 p.m. EST (1800 GMT).

HOLD. The countdown has entered an unplanned hold at T-minus 7 minutes, 45 seconds. The reason for the halt in the countdown is unknown. SpaceX's webcast audio is choppy and intermittent.

Today's static fire test at Complex 40 appears to be progressing as planned toward an engine start in about 13 minutes.

Critical steps expected to occur in the last 10 minutes of the countdown include the alignment of the internal navigation system, a second stage engine steering check, transferring the rocket to internal power, liquid oxygen system closeouts, and the start of the automated sequence.

SpaceX reports the rocket is now fully loaded with helium pressurant for today's simulated launch attempt.

T-minus 30 minutes and counting. SpaceX is now targeting 12:48 p.m. EST (1748 GMT) for ignition of the Falcon 9 engines.

The Falcon 9 rocket's nine Merlin first stage engines will be ignited today for 3.5 seconds, enough time to verify systems on the ground and the launch vehicle responsible for the final few seconds of the countdown. The engines will be at full power for approximately 2 seconds.

The engines will produce nearly 1 million pounds of total sea level thrust, more than four times the power of a 747 jumbo jet at full throttle. The engines consume about 3,200 pounds of kerosene and liquid oxygen propellants per second, according to SpaceX.

SpaceX's webcast has begun and everything is on track for ignition of the Falcon 9's main engines at 12:45 p.m. EST (1745 GMT).

The strongback structure at the launch pad has been retracted away from the Falcon 9 rocket and the fueling procedure is underway at Complex 40.

Liquid oxygen vapors just began streaming from the 154-foot-tall rocket, indicating the super-cold oxidizer is being loaded into the rocket for today's engine test.

The liquid oxygen is stored in a 125,000-gallon sphere in the southeast quadrant of Complex 40. The rocket's RP-1 kerosene fuel is kept in cylinder-shaped tanks on the west side of the pad.

Engineers plan to load nearly 39,000 gallons of super cold liquid oxygen and almost 25,000 gallons of kerosene fuel into the first stage tanks. About 7,300 gallons of liquid oxygen and 4,600 gallons of kerosene will go into the second stage.

The propellants flow into the first stage through the launch mount at the base of the rocket. Kerosene and liquid oxygen will be pumped up the strongback umbilical tower to enter the second stage.

A few dozen engineers and managers are stationed inside the SpaceX Launch Control Center near the south gate to Cape Canaveral Air Force Station.

Ignition of the Falcon's nine first stage Merlin engines is set for 12:45 p.m. EST (1745 GMT).

SpaceX just announced the earliest today's static fire could occur is 12:45 p.m. EST (1745 GMT). The company has not disclosed the reason for the delays this morning, but weather is favorable for the engine test.

View photos taken by SpaceX of yesterday's rollout and erection of the Falcon 9 rocket at Complex 40.

SpaceX says today's Falcon 9 rocket static fire test is now scheduled for no earlier than 12 p.m. EST (1700 GMT). The company plans to webcast the test beginning one hour before ignition.

SpaceX plans a brief firing of the Falcon 9 rocket's main engines around 9 a.m. EST (1400 GMT) Friday on the launch pad at Cape Canaveral, Fla.

Bolted to a transporter-erector device, the 15-story rocket rolled out of the SpaceX assembly hangar and arrived at Complex 40 Thursday. The 600-foot journey was accomplished on rail tracks, then the rocket was hydraulically lifted upright Thursday afternoon.

A lean team of technicians was expected to begin methodically hooking up the transporter to the launch pad with a series of pins and flanges after carefully lining up the rocket on top of the flame trench.

The flanges link the rocket with ground storage tanks containing liquid oxygen, kerosene fuel, helium, gaserous nitrogen and the first stage ignitor source called triethylaluminum-triethylborane, better known as TEA-TEB.

Workers must also connect electrical and data cables between the launch pad and the transporter, which serves as the interface between the ground and the rocket.

The launch team will load kerosene and liquid oxygen into the rocket around sunrise Friday, aiming for a brief ignition of the first stage's nine Merlin engines at 9 a.m. EST.

The rehearsal is the final prelaunch simulation of the countdown, and the SpaceX team will conduct the test from the company's Launch Control Center at the south end of Cape Canaveral Air Force Station near Port Canaveral.

If the engine test goes as planned, officials say the Falcon 9 could blast off as soon as 9 a.m. EST Tuesday.

The test flight of SpaceX's Dragon cargo capsule remains set for Dec. 7, assuming final launch preps go as planned and an engine firing is successful Friday, a company spokesperson said Tuesday.

The second Falcon 9 rocket, now inside horizontal hangar at Cape Canaveral's Complex 40, will roll to the pad and be lifted upright later this week, according to Kirstin Brost, a SpaceX spokesperson. The Falcon 9's nine first stage engines will ignite for about 3.5 seconds Friday in a traditional prelaunch rehearsal of countdown procedures and check of propulsion system health.

The engine test could occur as early as about 9 a.m. EST (1400 GMT) Friday.

Liftoff of the 154-foot-tall booster is possible next Tuesday in a launch window opening at 9:03 a.m. EST and closing at 12:22 p.m. EST (1403-1722 GMT).

Launch opportunities are also available Dec. 8 and Dec. 9 with the same launch window, according to NASA.

The Falcon 9 will deposit the Dragon spacecraft in a 186-mile-high orbit, where it will spend several hours testing its computers, communications and navigation systems, and Draco thrusters for in-space maneuvering and a de-orbit burn.

Officials previously said the Dragon will accomplish one-to-three orbits before splashing down by parachute in the Pacific Ocean.

The Federal Aviation Administration last week issued SpaceX a commercial re-entry license for the mission, the first such approval ever granted for the return of a private spacecraft.

NASA and SpaceX officials will hold a press conference the day before launch to discuss the mission. Another news conference at the Kennedy Space Center is planned about one hour after landing, NASA announced Tuesday.

The Federal Aviation Administration granted SpaceX a commercial re-entry license Monday for next month's roundtrip test flight of the Dragon spacecraft, clearing a major regulatory hurdle before the first demo under NASA's commercial cargo development program.

SpaceX is aiming to launch the first test flight of the Dragon cargo spacecraft as soon as Dec. 7, a delay of two-and-a-half weeks to give teams more time to complete testing on the ground.

The Falcon 9 rocket will have Dec. 8 and 9 as backup dates.

The company announced the new launch date Monday as officials submitted a request to the U.S. Air Force, which controls the flight manifest from Cape Canaveral, Fla.

The mission was supposed to get off the ground Nov. 18, then delays of a Delta 4-Heavy rocket pushed the Falcon 9 target date a few days later. The Delta launch with a National Reconnaissance Office payload is now scheduled for Nov. 18.

SpaceX opted to reschedule the launch after the Delta 4-Heavy, the Thanksgiving holiday, and the next window for the shuttle Discovery to begin its mission.

"There is more testing that would yield a meaningful improvement in mission success," said Kirstin Brost, a SpaceX spokesperson.

The launch was previously delayed from Nov. 8 to Nov. 18 to run additional simulations, verifying the flight's hardware and software work in lockstep during the demonstration mission, which is slated to last several hours.

SpaceX is also awaiting approval of a re-entry license from the Federal Aviation Administration, the U.S. government regulatory agency for commercial spaceflight.

After circling Earth between one and three times, the Dragon space capsule will fire thrusters to drop from orbit and fall to a parachuted landing in the Pacific Ocean off the coast of California.

SpaceX's launch date is also tied to the scheduled blastoff of Discovery, which will occur Nov. 30, at the earliest. One of the shuttle's solid rocket booster recovery vessels will also support the Falcon 9 launch and attempt to retrieve the rocket's first stage.

If liftoff remains set for Dec. 7, engineers plan an on-the-pad test firing Dec. 3 of the rocket's nine first stage engines.

SpaceX has reset the launch of a crucial test flight of the Dragon capsule for no earlier than Nov. 18, giving engineers extra time to simulate the ship's brief but ambitious mission.

SpaceX rolled the second Falcon 9 rocket to its seaside Florida launch pad and pumped propellant into the booster's fuel tanks Wednesday in a preflight countdown rehearsal.

Six weeks after the first Falcon 9 rocketed into orbit, pieces of the second launcher have begun arriving at Cape Canaveral for a shakedown flight of SpaceX's Dragon capsule in September, according to the company's top executive.