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The spacecraft will extend weather observations over the Asia-Pacific, supplying key data to forecasters from Japan, Australia, New Zealand, Southeast Asia and neighboring regions.
The burn will last about 3 minutes, 17 seconds, to place the Himawari 8 satellite into a geostationary transfer orbit with a high point of 35,976 kilometers (22,354 miles), a low point of 250 kilometers (155 miles) and an inclination of 22.4 degrees.
A second burn of the second stage engine is scheduled to begin at T+plus 23 minutes, 50 seconds.
Altitude is now 268 kilometers and velocity is about 6,100 m/s.
Rocketing east across the Pacific Ocean, the second stage LE-5B engine will fire for more than five minutes during this first burn of the mission to place the vehicle into a parking orbit.
A second burn will come later to put Himawari 8 into a higher-altitude geostationary transfer orbit.
The ignition sequence of the first stage engine begins 5.2 seconds before liftoff. Solid rocket booster ignitions occurs at T-zero.
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.
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 east 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 at about the two-minute point. The 13.1-foot diameter payload shroud will separate at T+plus 4 minutes, 5 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 five minutes before shutting down at T+plus 12 minutes, 12 seconds.
After a nearly 12-minute coast, the second stage will reignite for a 3-minute, 17-second burn.
Deployment of the Himawari 8 satellite is expected at T+plus 27 minutes, 57 seconds.
Officials just gave the "go" to enter the terminal count, which began at 0416 GMT. The final hour of the countdown will prepare the rocket, the payloads, and ground systems for flight.
The H-2A rocket for today's launch is flying in the "202" configuration with two large 15-meter-long (49-foot) solid rocket boosters and without any of the smaller strap-on boosters sometimes used to augment the launcher's thrust.
It also features a standard four-meter (13.1-foot) diameter nose shroud, which encloses the Himawari 8 spacecraft for the first few minutes of flight through the lower atmosphere.
The lead contractor for the H-2A rocket is Mitsubishi Heavy Industries.
GPM weighs about 3.5 metric tons, or approximately 7,700 pounds, at the time of launch. It was built by Mitsubishi Electric Co. in Japan.
The spacecraft is fitted with the Advanced Himawari Imager, a camera that can scan the entire disk of Earth visible to Himawari 8 every 10 minutes, an improvement from every half-hour.
The instrument, which can see in 16 spectral bands, was manufactured in the United States by Exelis Geospatial Systems.
Himawari 8 is the eighth satellite in the Himawari -- which means sunflower -- series of spacecraft launched since 1977.
The satellite will raise its orbit to an altitude about 22,300 miles over the equator, where it will park itself at 140 degrees east longitude for an eight-year primary mission. The craft's components are designed to last up to 15 years.
It replaces the MTSAT 2 weather satellite launched in 2006.
We have also posted a cutaway diagram of the H-2A launch vehicle.
Another "go/no go" decision point is coming up soon, before the countdown enters the terminal phase at T-minus 60 minutes.
The Himawari 8 spacecraft is heading for a geostationary transfer orbit with an apogee of 35,976 kilometers, or 22,354 miles, a perigee of 250 kilometers, or 155 miles, and an inclination of 22.4 degrees.
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 0416 GMT. Liftoff remains set for 0516 GMT (1:16 a.m. EDT), or 2:16 p.m. local time at the Tanegashima Space Center in southern Japan.
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 four flights of the H-2B rocket with the H-2 Transfer Vehicle, an unmanned cargo ship for the International Space Station. In all, 35 rockets have departed Earth from the Yoshinobu complex since 1994. The most recent flight was an H-2A rocket launch in May 2014.
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 orange, black and white rocket arrived at Launch Pad No. 1 at Tanegashima's Yoshinobu launch complex a few hours ago to begin preparations for fueling, including the connection of fuel lines and data and electrical cables between the ground complex and the rocket.
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