A Japanese H-2A rocket deployed four satellites in orbit Thursday, putting up a research mission to track the changing role of water in Earth's climate and a South Korean payload to gather high-resolution photos for environmental monitoring and security authorities.

The 187-foot-tall launcher blasted off at 1639 GMT (12:39 p.m. EDT) from the Tanegashima Space Center, a picturesque island spaceport in southern Japan. The rocket soared south from Tanegashima, its hydrogen-fueled main engine and twin solid rocket boosters rising into the sky in a ball of orange flame.

The H-2A rocket's upper stage reached orbit about 15 minutes after liftoff, then deployed four satellites for Japan and South Korea.

Read our full story.

We don't expect any live updates on the separation of this mission's secondary payloads. The JAXA webcast has ended, but the space agency is expected to issue a press release later today.

This marks the H-2A rocket's 20th successful flight in 21 attempts. It is the 15th consecutive success for the Japanese launcher.

The larger H-2B rocket, which launches Japan's resupply ships to the International Space Station, has flown flawlessly two times so far.

Data indicates JAXA's GCOM W1, or Shizuku, satellite successfully deployed from the H-2A rocket's second stage. A round of applause just erupted in the control center.

Two more small secondary passengers remain to be released from the rocket. The SDS 4 small demonstration satellite for JAXA and the Horyu 2 student-build craft will separate 33 minutes and 50 minutes after liftoff, respectively.

The H-2A upper stage is re-orienting to jettison the adapter covering Shizuku, the other primary payload on this flight which flew to orbit in the lower position in the rocket's dual-payload stack.

Kompsat 3 separation! South Korea's high-resolution imaging satellite, a commercial payload for the H-2A rocket, has been released from the launcher over Indonesia.

T+plus 15 minutes, 23 seconds. The second stage's LE-5B engine has cut off and the H-2A rocket should now be in orbit.

T+plus 9 minutes. No problems have been reported thus far in the launch phase of the mission. Second stage cutoff is scheduled for T+plus 15 minutes, 26 seconds.

T+plus 6 minutes, 58 seconds. First stage main engine cutoff, staging and second stage ignition have all occurred on time, according to JAXA. Velocity is now about 3,580 meters per second.

The second stage LE-5B engine will fire for more than eight minutes during this first burn of the mission to place the vehicle into low Earth orbit.

T+plus 4 minutes, 15 seconds. JAXA reports the two-piece upper payload fairing has been released from the rocket. The H-2A is now being powered by its LE-7A main engine at an altitude of 155 kilometers and a velocity of 1,805 meters per second.

T+plus 2 minutes, 10 seconds. Burnout and separation of the twin solid rocket boosters that provided the bulk of thrust at liftoff. Altitude is now about 60 kilometers.

T+plus 60 seconds. The 18-story rocket has surpassed Mach 1 and is now experiencing the most extreme aerodynamic forces of its flight.

LIFTOFF! The H-2A rocket has blasted off from southern Japan with a water cycle research craft and a Korean imaging satellite.

T-minus 60 seconds and counting. Thousands of gallons of water are now being poured over the launch platform to cushion the structure from intense acoustic vibrations at launch. In the countdown's final minute, the rocket will be armed and the guidance system will start.

The ignition sequence of the first stage engine begins 5.2 seconds before liftoff. Solid rocket booster ignitions occurs at T-zero.

T-minus 90 seconds. The first and second stage propellant systems have been readied for launch.

T-minus 3 minutes. The H-2A rocket has switched to internal power.

T-minus 4 minutes, 30 seconds. The automatic countdown sequence has started.

T-minus 5 minutes, 30 seconds. he weather is acceptable for launch today, according to JAXA.

The current conditions are a temperature of 66 degrees Fahrenheit and northeast winds of about 15 mph.

T-minus 7 minutes. The range safety system is reported ready for launch.

T-minus 10 minutes. Today's H-2A rocket launch will use the vehicle's "202" configuration with two 49-foot-long solid rocket boosters and no smaller strap-on motors used for the H-2A's heavier payloads.

The rocket is flying with a lengthened 4-meter diamter (13.1-foot diameter) payload fairing to accommodate the mission's two large primary passengers - Shizuku and Kompsat 3.

T-minus 12 minutes. In the final minutes of the countdown, an automated sequencer will control the final crucial steps before launch.

The automatic sequence will begin at T-minus 4 minutes, 30 seconds and computers will pressurize the H-2A's propellant tanks for flight at about T-minus 4 minutes, 20 seconds.

At about T-minus 3 minutes, the launcher will transition to internal battery power and remove external power.

Water will be released onto the launch pad deck beginning at T-minus 73 seconds to help suppress sound and acoustics during the ignition and liftoff. The vehicle's pyrotechnic and ordnance systems will be armed at T-minus 30 seconds and the rocket's guidance system initializes at T-minus 18 seconds. Batteries controlling solid rocket booster ignition are activated at T-minus 15 seconds.

Sparklers underneath the rocket's main engine ignite at T-minus 11.7 seconds to burn off residual hydrogen that could be an explosive hazard at main engine start.

T-minus 20 minutes. Engineers are uploading the latest upper level wind data into the H-2A's flight computer. The rocket will use the information to compute a specific steering profile based on the real launch day weather conditions.

At liftoff, the H-2A will be propelled upward from the launch pad on the power of a single hydrogen-burning LE-7A main engine and two solid rocket motors. The total liftoff thrust of the rocket is approximately 1.6 million force pounds.

The rocket will pitch south from Tanegashima, racing through the speed of sound in less than a minute and reaching an altitude of more than 30 miles in the first two minutes of flight.

After consuming their pre-packed solid propellant, the two strap-on boosters will jettison in two pairs just after the two-minute point. The 13.1-foot diameter payload shroud will separate at T+plus 4 minutes, 10 seconds after the H-2A rocket ascends above the discernable traces of Earth's atmosphere.

First stage main engine cutoff, stage separation and ignition of the second stage's LE-5B engine will occur nearly seven minutes into the mission. The second stage will burn for more than eight minutes before shutting down at T+plus 15 minutes, 26 seconds.

Deployment of the Kompsat 3 satellite is expected at T+plus 16 minutes, 16 seconds.

The H-2A rocket's dual-payload adapter will be jettisoned at T+plus 19 minutes, 21 seconds, exposing the Shizuku satellite in the lower position in the payload cylinder.

Shizuku will separate at T+plus 23 minutes, 11 seconds.

The mission's two secondary passengers, SDS 4 and Horyu 2, will complete their deployments by the launch's 50-minute point.

We will be broadcasting JAXA's webcast of today's launch. Be sure to hit reload for the video stream to appear above this text.

Now 60 minutes from the planned launch of the H-2A rocket.

Officials just gave the "go" to enter the terminal count, which began at 1539 GMT. The final hour of the countdown will prepare the rocket, the payloads, and ground systems for flight.

Today's H-2A launch includes a test of the second stage's performance. After deploying the mission's four payloads in the first 50 minutes after liftoff, the second stage will continue its flight to test improvements for future H-2A rockets.

The second stage's liquid hydrogen tank was painted white for today's launch for engineers to evaluate the paint's ability insulate the super-cold fuel tank and reduce the hydrogen's rate of evaporation. The experiment could allow future H-2A missions to last longer in space to reach higher orbits or release multiple types of satellites.

A second steering check of the rocket's engines has been accomplished, according to Mitsubishi Heavy Industries.

Another "go/no go" decision point is coming up soon, before the countdown enters the terminal phase at T-minus 60 minutes.

Today's three-minute launch window is timed for the GCOM-W1, or Shizuku, satellite to enter a formation of Earth observation spacecraft known as the A-Train. The A-Train satellites include craft from NASA and France, and Shizuku will become Japan's first contribution to the fleet.

The A-Train allows satellites equipped with different types of instruments to make measurements of Earth's surface, atmosphere and oceans around the same time, giving scientists a chance to compare results from each mission.

There are 90 minutes left in today's countdown before liftoff of the H-2A rocket with the Japan Aerospace Exploration Agency's first Global Change Observation Mission, or GCOM W1, and South Korea's Kompsat 3 imaging satellite.

GCOM W1 weighs about 4,389 pounds at the time of launch. It is nicknamed Shizuku, which means drop or dew in Japanese, because it will track precipitation, clouds, atmospheric water vapor, sea surface temperatures, sea ice, snow cover, and soil moisture.

Shizuku is a mission dedicated to water. It cost JAXA about $385 million, not including planned operational costs.

The H-2A rocket is also carrying a Kompsat 3, which includes an electro-optical imaging camera to collect high-resolution imagery for South Korea.

The Korea Aerospace Research Institute, which manages the mission, says Kompsat 3 will be used for mapping, agricultural, environmental and ocean monitoring purposes. Kompsat 3's camera will resolve objects as small as 70 centimeters on Earth's surface.

Two other satellites - a small JAXA demonstration spacecraft and a university-built experimental platform - will also launch on today's H-2A flight.

The H-2A launch from Japan today will be the second of three planned space launches occurring around the world within a five-hour period.

A Soyuz rocket blasted off about an hour ago from the Plesetsk Cosmodrome in northern Russia with a military photo surveillance satellite for the Russian military.

And a commercial Proton launcher is on the pad at the Baikonur Cosmodrome in Kazakhstan to loft the Nimiq 6 communications payload for Telesat, a communications satellite operator based in Ottawa, Canada.

Follow along with the Proton's planned 1912 GMT (3:12 p.m. EDT) blastoff in our status center dedicated to that flight.

Check out a launch timeline describing when major events occur during the H-2A rocket's ascent into orbit.

We have also posted a ground track map and a diagram of the H-2A launch vehicle.

Radio checks have been completed between the rocket and ground stations.

Mitsubishi Heavy Industries, the H-2A rocket's contractor and commercial operator, reports the liquid hydrogen and liquid oxygen tanks aboard the launcher are now full of super-cold cryogenic propellant.

The next few hours of the countdown will be spent activating and checking out a variety of rocket systems, including radio frequency links with tracking stations. Another steering check of the rocket's main engine is also planned.

After testing is completed, officials will give the go-ahead for the terminal countdown scheduled to start at 1539 GMT.

Liftoff remains set for 1639 GMT (12:39 p.m. EDT), or 1:39 a.m. local time at the Tanegashima Space Center in southern Japan.

Slew checks of the H-2A rocket's first stage engine have been completed, verifying the powerplant will be able to steer the launcher during ascent.

Fueling of the rocket with cryogenic propellant is currently underway.

Check out photos of the H-2A rocket rolling to the launch pad a few hours ago.

Safety officials have established road blocks 400 meters from Launch Pad No. 1 of the Yoshinobu launch complex. The Yoshinobu launch complex was built for the H-2 rocket program that began operations in 1994 and has since been modified for use by the more powerful and reliable H-2A rocket family.

The pads are positioned on a rocky outcrop on the southeastern flank of Tanegashima Island, which lies about 80 miles south of Kagoshima, Japan.

The complex features two pads for the H-2A and H-2B rockets. Launch Pad No. 2 has been used for two flights of the H-2B rocket with the H-2 Transfer Vehicle, an unmanned cargo ship for the International Space Station. In all, 27 rockets to date have departed Earth from the Yoshinobu complex since 1994. The most recent flight was an H-2A rocket launch in December 2011.

Launch officials report they are go for cryogenic fueling of the H-2A rocket. The launcher's two stages consume liquid hydrogen and liquid oxygen propellants. Two strap-on boosters attached to the first stage are already packed with solid fuel.

The LE-7A and LE-5B engines on each stage burn the super-cold propellants during the flight. Because the propellant is stored under cryogenic conditions, it must be gradually replenished throughout the countdown to ensure proper levels of fuel are inside the rocket at liftoff.

JAXA and Mitsubishi Heavy Industries, the H-2A rocket's prime contractor, report all systems are functioning well.

The H-2A rocket for Thursday's launch just arrived at the pad after a half-hour rollout from the Vehicle Assembly Building.

Once the launch platform is firmly attached to the pad, workers will begin connecting fuel lines and data and electrical cables between the complex and the rocket.

Fueling of the H-2A rocket should begin about eight hours before liftoff, which remains scheduled for 1639 GMT (12:39 p.m. EDT).

The launch will mark the 21st flight of Japan's H-2A rocket since it debuted in 2001. All but one of the missions have been successful.

A Japanese H-2A rocket will launch a water cycle research satellite and a South Korean observation payload into orbit Thursday.

Rollout of the launcher from the Vehicle Assembly Building to Launch Pad No. 1 at the Tanegashima Space Center is expected at about 0300 GMT Thursday (11 p.m. EDT; 12 p.m. Japanese time). It will take about a half-hour for the rocket to make the 1,500-foot journey.

The two-stage booster will roll on rail tracks atop a mobile transporter.

Liftoff is scheduled for a three-minute window opening at 1639 GMT (12:39 p.m. EDT) Thursday, or 1:39 a.m. local time at the Tanegashima launch site, which is located on an island off the south coast of Kyushu, the southernmost of Japan's main islands.