ISRO chairman K. Radhakrishnan confirms ground controllers have established contact with INSAT 3D.

ESA reports signals from the Alphasat spacecraft have been received at a ground station in Beijing, confirming the health of the satellite following launch.

Today's launch marks the 56th consecutive success for the Ariane 5 rocket since 2003.

Separation of the INSAT 3D satellite is confirmed. The Indian weather satellite is beginning a seven-year lifetime to help meteorologists track storms and weather over India.

Plus+29 minutes, 40 seconds. The Sylda dual-payload adapter has jettisoned, setting the stage for separation of INSAT 3D at Plus+32 minutes, 41 seconds.

Separation of the Alphasat communications satellite confirmed, beginning a dual mission to serve customers on-the-move and demonstrate a new European satellite platform built by Astrium and Thales Alenia Space.

Plus+25 minutes, 15 seconds. The rocket's second stage shut down as scheduled.

Plus+24 minutes. The rocket is surpassing a speed of 20,000 mph. Shutdown of the upper stage is about a minute from now.

Plus+21 minutes. The upper stage will shut down at Plus+25 minutes, 1 second, after reaching a target orbit with a low point of 154 miles, a high point of 22,335 miles, and an inclination of 3.5 degrees.

Plus+19 minutes. The cryogenic HM7B engine continues to functional well.

Plus+17 minutes. Altitude is 172 km and velocity is 8.11 km/s. After intentionally losing altitude in order to gain speed, the Ariane 5 is now climbing again.

Plus+15 minutes. A tracking station on Ascension Island in the Atlantic Ocean is now receiving signals from the Ariane 5.

Plus+12 minutes. This upper stage engine burn will last about 16 minutes.

Plus+9 minutes, 25 seconds. The main cryogenic stage's Vulcain engine has cut off and the spent stage has separated. It will fall back into the atmosphere prior to completing an orbit of Earth.

And the upper stage's HM7B engine is now firing to inject the Alphasat and INSAT 3D satellites into orbit.

Plus+8 minutes. Now in range of a communications station in Natal, Brazil, the launcher is about to shut down its first stage and ignite its cryogenic upper stage.

Plus+7 minutes. Altitute is 172 km and velocity is 4.8 km/s.

Plus+3 minutes, 30 seconds. Separation of the rocket's nose cone has been confirmed. The Ariane 5 core stage will continue burning until about Plus+9 minutes into the mission.

Plus+2 minutes, 30 seconds. The solid rocket boosters have been jettisoned from the Ariane 5 rocket's core stage. The liquid-fueled Vulcain 2 main engine continues to fire to propel the vehicle and its satellite payload to space.

Plus+60 seconds. The vehicle is on the proper heading as it rides the power of the twin solid rocket boosters and main stage liquid-fueled engine. Ariane 5 has already passed the speed of sound.

Liftoff of an Ariane 5 rocket, taking European communications to new heights and bolstering weather forecasts for India.

Minus-1 minute. A fast-paced series of events leading to launch will begin at Minus-37 seconds when the automated ignition sequence is started. The water suppression system at the launch pad will start at Minus-30 seconds. At Minus-22 seconds, overall control will be given to the onboard computer. The Vulcain main engine will be readied for ignition with hydrogen chilldown starting at Minus-18 seconds.

The residual hydrogen burn flares will fire beneath the Vulcain engine at Minus-6 seconds to burn away any free hydrogen gas. At Minus-3 seconds, onboard systems take over and the two inertial guidance systems go to flight mode. Vulcain main engine ignition occurs at Minus-0 seconds with checkout between Plus+4 and 7 seconds. If there are no problems found, the solid rocket boosters are ignited at Plus+7.0 seconds for liftoff at Plus+7.3 seconds.

The Vulcain 2 engine and twin solid rocket boosters will generate 2.6 million pounds of thrust at liftoff, enough to send the 1.7-million-pound launcher skyward.

Minus-2 minutes. The Vulcain main engine supply valves are being opened. And the ground valves for engine chilldown are being closed.

Minus-3 minutes. The scheduled launch time has been loaded into the rocket's main computer system. The main stage tank pressures should now be at flight level.

Minus-4 minutes. Pressurization is now underway for the main cryogenic stage's liquid oxygen and hydrogen tanks. Also, final pyrotechnic arming is starting.

Minus-5 minutes. All status panel lights remain green, indicating no problems right now that could prevent an on-time blastoff.

Minus-6 minutes. Liquid hydrogen and liquid oxygen supplies of the main cryogenic stage are being verified at flight level. Also, the pyrotechnic line safety barriers are being armed.

Minus-7 minutes and counting. The synchronized sequence has started. Computers are now in control of this automated final phase of the launch countdown to prepare the rocket and ground systems for liftoff. There are three computers running the countdown - one aboard the Ariane 5 and two redundant computers at the launch complex.

Minus-10 minutes. The synchronized launch sequence will begin in three minutes.

Minus-12 minutes. All parameters, including weather and technical readiness, are reporting green on the status board inside the Jupiter control room at the Guiana Space Center.

Minus-20 minutes. The Synchronized Sequence is being prepped for activation. This computer-run sequence assumes control of the countdown at the Minus-7 minute mark to perform the final tasks to place the rocket and pad systems in launch configuration.

At Minus-4 seconds, the rocket's onboard computer will take over control of main engine start, health checks of the powerplant and solid rocket booster ignition commanding for liftoff.

Minus-35 minutes. Today's launch will carry a European satellite named Alphasat, demonstrating a powerful new communications satellite platform and sophisticated technologies for the European Space Agency and Inmarsat, a British mobile communications firm.

The public-private partnership, led by ESA, Inmarsat and European satellite-builders Astrium and Thales, is worth more than $1 billion.

The Ariane 5 rocket is also launching INSAT 3D, an Indian weather satellite built to deliver higher-resolution imagery of clouds and storms to meteorologists.

It will take nearly 33 minutes to inject the satellites, which have a combined mass of approximately 19,335 pounds. Get an overview of the launch sequence.

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Minus-60 minutes. All parameters continue to look good for launch in one hour. A communications check between ground stations and the rocket should be concluding now.

Here are some statistics on today's launch:

• 214th Ariane rocket launch since 1979
• 70th Ariane 5 launch since 1996
• 40th Ariane 5 ECA launch since 2002
• 8th Inmarsat satellite launched on Ariane
• 16th Indian satellite launched on Ariane
• 5th launch from Guiana Space Center in 2013
• 3rd Ariane 5 launch in 2013

Fueling of the Ariane 5 rocket with cryogenic liquid hydrogen and liquid oxygen is underway, and chilldown of the first stage's Vulcain 2 main engine has begun to prepare the engine for its 9-minute firing in today's mission.

Meanwhile, ESA reports the launch window is now set to open at 1954 GMT (3:54 p.m. EDT), one minute later than previously planned.

Check out a timeline of today's launch events.

An Ariane 5 rocket is set to take off from French Guiana on Thursday with a sophisticated European communications satellite to test new broadcast technologies and an Indian weather satellite.

The 17-story rocket moved to the launch pad Wednesday, arriving after a 1.7-mile journey on rail tracks at the Guiana Space Center on the northern coast of South America.

Liftoff from the ELA-3 launch pad is set for 1953 GMT (3:53 p.m. EDT; 4:53 p.m. local time), at the opening of a 78-minute launch window.

It will be the third Ariane 5 launch of the year, coming after another dual-payload commercial launch in February and the June 5 launch of the European Space Agency's Automated Transfer Vehicle on a resupply mission to the International Space Station.

The flight will loft the Alphasat and INSAT 3D satellites into a geostationary transfer orbit, targeting an orbit with a high point of 22,335 miles, a low point of 154 miles, and an inclination of 3.5 degrees, according to data provided by Arianespace, the French operator of the Ariane 5 rocket.

Alphasat and INSAT 3D are housed inside the Ariane 5's 17.7-foot-diameter payload fairing, with Alphasat riding in the upper position mounted on a Sylda dual-payload adapter.

Alphasat is a public-private partnership between ESA, prime contractor EADS Astrium, and Inmarsat, a British telecommunications company. The 14,658-pound spacecraft inaugurates a new satellite platform known as Alphabus, which could provide a flexible bus for future craft serving a wide range of communications missions.

The Alphasat program allows ESA to foster technological innovation in Europe, while Inmarsat will use the satellite to serve mobile communications clients.

INSAT 3D is India's next weather satellite, offering improved imaging of clouds and storms at night and better resolution than previous meteorological craft.

The countdown is scheduled to begin Thursday at 0823 GMT (4:23 a.m. EDT). A check of the launcher's electrical systems will occur at 1223 GMT (8:23 a.m. EDT).

Workers will also put finishing touches on the launch pad, including the closure of doors, removal of safety barriers and configuring fluid lines for fueling.

The launch team will begin the process to fuel the rocket with super-cold liquid hydrogen and liquid oxygen propellants at 1453 GMT (10:53 a.m. EDT). First, ground reservoirs will be pressurized, then the fuel lines will be chilled down to condition the plumbing for the flow of super-cold liquid hydrogen and liquid oxygen, which are stored at minus 423 degrees Fahrenheit and minus 298 degrees Fahrenheit, respectively.

It will take approximately two hours to fill the Ariane 5 core stage tanks.

A similar procedure for the Ariane 5's cryogenic upper stage will commence at 1553 GMT (11:53 a.m. EDT).

Chilldown conditioning of the Vulcain 2 first stage engine will occur at 1653 GMT (12:53 p.m. EDT), and a communications check between the rocket and ground telemetry, tracking and command systems is scheduled for 1843 GMT (2:43 p.m. EDT).

The computer-controlled synchronized countdown sequence will begin seven minutes before launch to pressurize propellant tanks, switch to on-board power and take the rocket's guidance system to flight mode.

The Vulcain 2 engine will ignite as the countdown clock reaches zero, followed by a health check and ignition of the Ariane 5's solid rocket boosters seven seconds later to send the 1.7 million-pound launcher skyward.

Five seconds after blastoff, the rocket will begin pitching east from the ELA-3 launch pad, surpassing the speed of sound less than a minute into the mission. The Ariane 5's twin solid rocket boosters will jettison 2 minutes and 23 seconds after liftoff.

Once above the dense atmosphere, the launcher's payload fairing will fall away at an altitude of about 67 miles. The Ariane 5's first stage will shut down 9 minutes after liftoff, followed moments later by stage separation and ignition of the hydrogen-fueled cryogenic HM7B upper stage engine.

The rocket's upper stage will fire for more than 16 minutes, accelerating to a velocity of 5.8 miles per second.

The release of Alphasat is scheduled for 27 minutes, 39 seconds. The rocket's barrel-shaped Sylda 5 dual-payload adapter will be jettisoned a few minutes later.

INSAT 3D will separate from the lower portion of the payload stack at 32 minutes, 41 seconds.