Today's successful launch marks the completion of SpaceX's fourth mission this year.

AsiaSat 8 separation! The AsiaSat 8 spacecraft has deployed from the Falcon 9 upper stage to begin a 15-year service life broadcasting television, broadband data and other services across China, India, Southeast Asia and the Middle East.

SpaceX reports the Falcon 9 rocket's second stage Merlin 1D engine reignited successfully.

At this point in the flight, the second stage should have re-ignited its engine for a brief burn lasting just over a minute. The stage would have then re-oriented for deployment of the AsiaSat 8 satellite about now.

SpaceX officials have made no announcement yet.

The webcast has concluded now that the Falcon 9 is in a parking orbit. Re-ignition of the upper stage should occur at about 4:26 a.m. EDT (0826 GMT) for a burn of just over one minute.

Separation of the AsiaSat 8 satellite will come at 4:32 a.m. EDT (0832 GMT).

We expect an update from SpaceX soon after those milestones are achieved.

Second stage shutdown! Falcon 9 has achieved a preliminary parking orbit with a high point of 200 kilometers and a low point of 176 kilometers, with an orbital inclination of 27.7 degrees to the equator. SpaceX officials say that is close to prelaunch predictions.

T+plus 8 minutes. About 40 seconds until the second stage Merlin engine is supposed to shut down as the vehicle reaches orbit. The rocket is aiming for an initial parking orbit with AsiaSat 8, and it will re-ignite later to boost the satellite into a geosynchronous transfer orbit reaching 35,786 kilometers (22,236 miles) above Earth.

T+plus 7 minutes, 30 seconds. The kerosene-fueled Merlin 1D upper stage engine generates about 161,000 pounds of thrust in vacuum. Altitude is 180 km, velocity is 5.6 km/s, downrange distance is 1,150 km east of Cape Canaveral.

T+plus 6 minutes, 30 seconds. Everything reported to be going well with this second stage engine firing. The Merlin vacuum engine uses an ultra-thin niobium nozzle extension for greater efficiency in the upper atmosphere.

T+plus 5 minutes, 30 seconds. Velocity of the Falcon 9 is 3.8 km/second and downrange distance is 570 km as the upper stage Merlin 1D engine continues its burn.

T+plus 3 minutes, 50 seconds. The SpaceX-built 5.2-meter diameter payload fairing has separated.

T+plus 3 minutes. 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 approximately 5-minute, 33-second 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.

And chilldown of the second stage's vacuum-rated Merlin 1D engine should be starting in preparation for its ignition.

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

T+plus 30 seconds. The Falcon 9 rocket's pitch program has initiated to put the 224-foot-tall rocket on an easterly trajectory from Cape Canaveral.

LIFTOFF of the Falcon 9 rocket with AsiaSat 8, launching a satellite to beam television across China, India, Southeast Asia and the Middle East.

T-minus 60 seconds. 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 from the ground facility's Niagara system 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' ignitor moments before the powerplants actually ramp up to full power.

T-minus 90 seconds 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 4 a.m. EDT (0800 GMT).

T-minus 2 minutes and counting. The rocket's Merlin 1D engines have been chilled down for ignition.

T-minus 2 minutes, 30 seconds. The strongback has been locked in to launch position.

T-minus 3 minutes and counting. The rocket's destruct system is on internal power and being armed, and liquid oxygen topping is being terminated.

The strongback has retracted into the launch position more than 20 degrees from the rocket.

The second stage thrust vector steering system has checked out and is ready for flight.

T-minus 5 minutes and counting. The cradles connecting the strongback to the Falcon 9 rocket have opened.

T-minus 6 minutes and counting. The Falcon 9 rocket is now operating on internal power.

The strongback umbilical tower will soon be lowered a few degrees to clear the rocket for launch. The procedure begins with opening of cradles gripping the rocket at attach points, then hydraulics lower the tower into launch position.

T-minus 6 minutes, 30 seconds. The Falcon 9's heaters are being deactivated, and the rocket will be transitioned to internal power in a few seconds.

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.

The launch danger area around Cape Canaveral is clear for launch.

T-minus 8 minutes and counting. Good chilldown continues on the first stage engines, and closeouts of the upper stage's gaseous nitrogen attitude control system are underway.

T-minus 9 minutes and counting. Prevalves leading to the Falcon 9's Merlin 1D first stage engines are opening, permitting super-cold liquid oxygen to flow into the engines to condition the turbopumps 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 and recycle to T-minus 13 minutes.

T-minus 12 minutes. The launch team has verified all consoles are go for liftoff at 4 a.m. EDT (0800 GMT).

All systems on the rocket and the AsiaSat 8 satellite, along with weather, are GO for launch.

T-minus 33 minutes and counting. The countdown clock has resumed for the 4 a.m. EDT (0800 GMT) launch time.

NEW LAUNCH TIME. Liftoff has been set for 4 a.m. EDT (0800 GMT), according to SpaceX.

SpaceX says the team is in no hurry as engineers assess data on the Falcon 9 rocket's first stage. There is still one hour left in today's launch window, so the countdown must resume in approximately 40 minutes to support a liftoff this morning.

The AsiaSat 8 spacecraft and ground systems are reported ready for launch as propellant continues to be pumped into the two-stage Falcon 9 rocket.

SpaceX has not supplied any further updates on the status of this morning's launch.

The countdown did not resume from T-minus 20 minutes, so it appears liftoff will occur some time after 3 a.m. EDT (0700 GMT).

The launch countdown is being reset for T-minus 20 minutes and holding. The launch team has been instructed to prepare for another launch attempt around 3 a.m. EDT (0700 GMT) at the earliest.

The launch team continues to evaluate data related to the abort earlier.

SpaceX says they are planning to recycle the countdown for another launch attempt within this morning's launch window.

SpaceX says the terminal countdown was aborted by an issue on the Falcon 9 rocket's first stage.

The launch vehicle has been safed as the SpaceX team backs out of the terminal countdown to prepare for another launch attempt this morning, assuming engineers resolve the problem that aborted the countdown.

SpaceX has not released any information on the cause of the abort.

The countdown is being recycled to T-minus 13 minutes while SpaceX engineers study the problem that triggered the last-minute abort. The launch pad's strongback structure is being raised back into position next to the Falcon 9 rocket.

The launch window this morning extends to 4:11 a.m. EDT (0811 GMT) if SpaceX can resolve whatever issue caused the hold in the countdown.

ABORT. The countdown was aborted less than a minute from liftoff.

T-minus 60 seconds. 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 from the ground facility's Niagara system 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' ignitor moments before the powerplants actually ramp up to full power.

T-minus 90 seconds 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 1:25 a.m. EDT (0525 GMT).

T-minus 2 minutes and counting. The rocket's Merlin 1D engines have been chilled down for ignition.

T-minus 2 minutes, 30 seconds. The strongback has been locked in to launch position.

T-minus 3 minutes and counting. The rocket's destruct system is on internal power and being armed, and liquid oxygen topping is being terminated.

The strongback has retracted into the launch position more than 20 degrees from the rocket.

The second stage thrust vector steering system has checked out and is ready for flight.

T-minus 5 minutes and counting. The cradles connecting the strongback to the Falcon 9 rocket have opened.

T-minus 6 minutes and counting. The Falcon 9 rocket is now operating on internal power.

The strongback umbilical tower will soon be lowered a few degrees to clear the rocket for launch. The procedure begins with opening of cradles gripping the rocket at attach points, then hydraulics lower the tower into launch position.

T-minus 6 minutes, 30 seconds. The Falcon 9's heaters are being deactivated, and the rocket will be transitioned to internal power in a few seconds.

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.

The launch danger area around Cape Canaveral is clear for launch.

T-minus 8 minutes and counting. Good chilldown continues on the first stage engines, and closeouts of the upper stage's gaseous nitrogen attitude control system are underway.

T-minus 9 minutes and counting. Prevalves leading to the Falcon 9's Merlin 1D first stage engines are opening, permitting super-cold liquid oxygen to flow into the engines to condition the turbopumps 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 and recycle to T-minus 13 minutes.

T-minus 12 minutes. The launch team has verified all consoles are go for liftoff at 1:25 a.m. EDT (0525 GMT).

All systems on the rocket and the AsiaSat 8 satellite, along with weather, are GO for launch. The AsiaSat 8 satellite was placed on internal battery power for liftoff a few minutes ago.

T-minus 15 minutes and counting. Here are some statistics on today's launch:

• 11th launch of a Falcon 9 rocket since 2010
• 16th launch of Falcon rocket family since 2006
• 10th Falcon 9 launch from Cape Canaveral
• 6th launch of a Falcon 9 v1.1 rocket
• 5th Falcon 9 v1.1 launch from Cape Canaveral
• 4th Falcon 9 night launch
• 4th Falcon 9 launch of 2014
• 11th launch from Cape Canaveral in 2014

T-minus 17 minutes and counting. The Falcon 9 rocket stands 224 feet tall and measures 12 feet in diameter. At liftoff, its nine Merlin 1D first stage engines will generate about 1.3 million pounds of thrust.

Keep up with the launch sequence with this timeline of key events during the Falcon 9's ascent to orbit.

T-minus 20 minutes and counting. The SpaceX webcast is beginning now.

The final poll of the launch team stationed in a control center will begin at T-minus 13 minutes before the countdown enters the final phase.

Liquid oxygen topping continues on the Falcon 9 rocket's first and second stages. The first stage is filled with about 850,000 pounds of propellant, and the second stage is loaded with about 200,000 pounds. Both stages burn RP-1 kerosene and liquid oxygen.

T-minus 30 minutes. Today's launch is heading for a geosynchronous transfer orbit with an apogee, or high point, of 35,786 kilometers (22,236 miles) and a perigee, or low point, of 185 kilometers (114 miles). The target inclination is 24.3 degrees.

Built by Space Systems/Loral of Palo Alto, Calif., the AsiaSat 8 satellite is destined for a slot 22,300 miles above the equator in geostationary orbit at 105.5 degrees east longitude, where its Ku-band and Ka-band payload will beam direct-to-home television broadcasts and other services to China, India, Southeast Asia, the Middle East and surrounding regions for 15 years.

Today's mission marks the third SpaceX Falcon 9 launch with a satellite heading for a geostationary transfer orbit after the Dec. 3 launch with the SES 8 communications satellite and the Jan. 6 liftoff of Thaicom 6. Such an orbit requires two burns of the Falcon 9's upper stage Merlin 1D engine, first to place the satellite into a low-altitude parking orbit, then to raise its apogee to geostationary altitude or higher.

AsiaSat of Hong Kong has another satellite at Cape Canaveral -- AsiaSat 6 -- being prepared for launch on another Falcon 9 rocket before the end of August.

T-minus 60 minutes. Skies are partly cloudy over Cape Canaveral as the countdown continues for liftoff at 1:25 a.m. EDT (0525 GMT) at the opening of a 2-hour, 46-minute launch window.

Weather balloons are being launched throughout the countdown to monitor winds aloft.

Today's flight is from Space Launch Complex 40, which was formerly used by the Air Force's Titan 4 rocket until its last flight from Florida in April 2005. SpaceX took over the pad and launched the first Falcon 9 rocket from there on June 4, 2010.

The second Falcon 9 launch on Dec. 8, 2010, sent SpaceX's first Dragon capsule into space on a two-orbit test flight for SpaceX's commercial cargo services to the space station. The December 2010 flight did not go to the space station, but it demonstrated Dragon's avionics and heat shield, culminating with splashdown in the Pacific Ocean.

SpaceX's next launch on May 22, 2012, launched the Dragon spacecraft on a NASA-sponsored test flight to the International Space Station. The 9-day Dragon mission delivered cargo to the space station and returned hardware from orbit with a splashdown in the Pacific Ocean on May 31.

On Oct. 7, 2012, SpaceX launched its fourth Falcon 9 rocket on the first operational Dragon resupply flight to the space station. The three-week mission delivered 882 pounds of cargo to the complex and returned to Earth on Oct. 28 with 1,673 pounds of equipment.

A Falcon 9 launch on March 1, 2013, put up another automated Dragon cargo craft en route to the space station with 1,869 pounds of supplies. It arrived at the outpost March 3 and stayed for 23 days before coming back to Earth with 2,668 pounds of return cargo.

The Falcon 9's first launch from Vandenberg Air Force Base in California occurred Sept. 29, 2013, and deployed Canada's Cassiope space weather research and communications demonstration satellite into polar orbit. The launch also marked the first flight of SpaceX's upgraded Falcon 9 v1.1 vehicle, which includes more powerful first stage engines, stretched fuel tanks and other changes.

SpaceX's first launch into geostationary transfer orbit occurred Dec. 3, 2013, with the SES 8 Ku-band and Ka-band direct-to-home broadcasting and network services to cover the Asia-Pacific region for SES of Luxembourg.

The Falcon 9 rocket launched again Jan. 6 with the Thaicom 6 telecom satellite to provide C-band and Ku-band communications services across Southeast Asia and Africa.

SpaceX's third operational cargo resupply flight to the space station lifted off April 18 on a Falcon 9 rocket, marking the first time the launcher flew with first stage landing legs in a bid to make the vehicle reusable. The Dragon spacecraft delivered supplies to the space station and returned to Earth a month later.

The Falcon 9's 10th flight July 14 placed six small washing machine-sized delay relay communications satellites into low Earth orbit for Orbcomm Inc.

Kerosene and liquid oxygen are being pumped aboard the two-stage Falcon 9 rocket. Both stages burn the mix of liquid propellants to fuel 10 Merlin 1D engines.

SpaceX says the webcast of today's launch will begin at 1:05 a.m. EDT (0505 GMT), about 20 minutes prior to liftoff, and continue through the first cutoff of the second stage engine about 10 minutes into the mission.

We will have the live webcast on this page.

If you are heading out to the beach or Port Canaveral to watch the launch, sign up for our Twitter feed to get occasional countdown 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.)

And if you are need tips on picking a good viewing spot, check out this authoritative guide on where to go.

Technicians rolled the Falcon 9 rocket to the launch pad Sunday, using hydraulics to lift the 224-foot-tall booster on its launch mount at Cape Canaveral's Complex 40.

Workers then began plugging into electrical and propellant lines ahead of the start of the countdown this evening.

No problems are reported at this stage in the launch preparations. Fueling of the two-stage rocket with RP-1 fuel -- a highly-refined kerosene -- and liquid oxygen should begin shortly after 9:30 p.m. EDT (0130 GMT).

The rocket is one of the tallest in the world. The Falcon 9's first and second stages measure 12 feet in diameter, and the SpaceX-built payload fairing housing the Thaicom 6 communications satellite is 17 feet in diameter (5.2 meters) and 43 feet tall.

Technicians rolled the Falcon 9 rocket to the launch pad Sunday, using hydraulics to lift the 224-foot-tall booster on its launch mount at Cape Canaveral's Complex 40.

Workers then began plugging into electrical and propellant lines ahead of the start of the countdown this evening.

No problems are reported at this stage in the launch preparations. Fueling of the two-stage rocket with RP-1 fuel -- a highly-refined kerosene -- and liquid oxygen should begin shortly after 9:30 p.m. EDT (0130 GMT).

The rocket is one of the tallest in the world. The Falcon 9's first and second stages measure 12 feet in diameter, and the SpaceX-built payload fairing housing the Thaicom 6 communications satellite is 17 feet in diameter (5.2 meters) and 43 feet tall.

A launch readiness review has given a "go" to continue final launch preparations for Tuesday's predawn launch of a Falcon 9 rocket with the AsiaSat 8 communications satellite.

The weather forecast for Tuesday's predawn launch window continues to predict generally favorable conditions, with a 30 percent chance thick clouds or cumulus clouds could violate the Falcon 9's launch weather rules.

Summertime afternoon thunderstorms are expected this afternoon, but the activity is expected to diminish overnight. There is still a slight chance of isolated showers during the launch window, according to a forecast issued this morning by the U.S. Air Force's 45th Weather Squadron.

"Residual cloudiness, showers and isolated thunderstorms will remain in the area overnight with most activity off shore," meteorologists wrote in a forecast summary. "The main concerns during the launch window are cumulus and thick clouds."

The launch window opens at 1:25 a.m. EDT (0525 GMT) and extends until 4:11 a.m. EDT (0811 GMT) Tuesday.

A Falcon 9 rocket is set for liftoff from Cape Canaveral early Tuesday, continuing a jam-packed sequences of launches by SpaceX for commercial and government customers after a slow start to the year.

Read our full story.

SpaceX is preparing for the next launch of its Falcon 9 rocket Tuesday with the AsiaSat 8 telecommunications payload, a satellite to broadcast television services across India, China, Southeast Asia and the Middle East.

The launch window Tuesday opens at 1:25 a.m. EDT (0525 GMT) and extends for 2 hours, 46 minutes.

The 22-story Falcon 9 launcher will be making its 11th flight, and its third mission to geostationary transfer orbit, the destination for most launch telecom satellites.

The two-stage rocket completed a customary prelaunch engine test Thursday, in which the rocket's nine first stage Merlin 1D engines fired for about three-and-a-half seconds at Cape Canaveral's Complex 40 launch pad. The rocket was restrained on the launch pad during the "static fire," which SpaceX conducts before each flight to ensure all systems are ready for liftoff.

The static fire occurred at the end of a practice countdown after the launch team loaded liquid oxygen and kerosene propellants into the launcher.

The outlook for Tuesday's predawn launch window calls for a 70 percent chance of favorable weather for liftoff.

There is a chance of isolated showers in the area, along with thick clouds that could violate the Falcon 9's weather rules.

An upper-level trough over the Gulf Coast states and a tropical wave moving north from the Florida straits are bringing increased moisture to Central Florida over the next couple of days, according to the weather team from the U.S. Air Force's 45th Weather Squadron at Cape Canaveral.

"These features will create widespread clouds, rain and thunderstorms late tonight and through the day Monday," forecasters wrote in Sunday's forecast. "The good news is these features will begin to move out of the Central Florida area late Monday and into Tuesday, though still creating a concern for cumulus and thick clouds in the launch window."

The official forecast calls for a chance of isolated rain showers, a few clouds at 3,000 feet, scattered clouds at 10,000 feet and broken clouds at 25,000 feet. The winds will be out of the southwest at 8 to 12 mph, and the temperature is predicted to be 80 degrees Fahrenheit.

There is a 30 percent chance weather conditions will prohibit liftoff Tuesday. The forecast for Wednesday morning's backup window improves with an 80 percent chance of favorable weather.