August 20, 2017

H-2A rocket rolls to launch pad with Japanese weather satellite

The H-2A rocket set to launch with the Himawari 9 weather satellite rolled out to its launch pad at the Tanegashima Space Center on Tuesday. Credit: MHI
The H-2A rocket set to launch with the Himawari 9 weather satellite rolled out to its launch pad at the Tanegashima Space Center on Tuesday. Credit: MHI

A sophisticated new Japanese weather satellite will ride an H-2A rocket into orbit Wednesday to start a 15-year mission tracking cyclones and helping meteorologists predict storm movements across the Asia-Pacific and Australia.

The Himawari 9 weather observatory is set to begin its trek to geostationary orbit more than 22,000 miles (nearly 36,000 kilometers) above Earth on Wednesday from the Tanegashima Space Center, a spaceport nestled on the southern flank of Tanegashima Island in southern Japan.

Himawari 9 is the second of two identical weather satellites owned by the Japan Meteorological Agency to offer more detailed and more timely imagery of storms, clouds and other weather systems to forecasters in Japan and across the Western Pacific.

Liftoff of the 174-foot-tall (53-meter) H-2A rocket, built by Mitsubishi Heavy Industries, is set for 0620 GMT (2:20 a.m. EDT) Wednesday at the opening of a launch window that extends until 0918 GMT (5:18 a.m. EDT).

Launch is set for 3:20 p.m. Japan Standard Time, and it will take nearly a half-hour for the H-2A rocket to place Himawari 9 into an initial geostationary transfer orbit, an egg-shaped loop around Earth with a high point of 22,354 miles (35,976 kilometers), a low point of 155 miles (250 kilometers) and a tilt of 22.4 degrees to the equator.

Japanese officials delayed the launch 24 hours due to a poor weather forecast that could have prevented rollout of the H-2A rocket from its integration hangar Monday.

The weather improved Tuesday, and ground crews at Tanegashima rolled out the H-2A rocket on its mobile launch table around 1630 GMT (12:30 p.m. EDT). The 1,600-foot (500-meter) journey from the vertical assembly building to the launch pad took about 40 minutes to complete, and technicians planned to plug the launch platform into ground electrical and propellant supplies before fueling begins in the final hours of the countdown.

Once the launch team checks out the rocket’s systems and loads it with cryogenic liquid hydrogen and liquid oxygen, an automated countdown sequencer will take over the final steps before liftoff.

The H-2A rocket will light its core LE-7A main engine, then ignite two strap-on solid rocket boosters to climb away from the launch pad atop nearly 1.4 million pounds of thrust.

The rocket’s flight computer will command the engine and booster nozzles to pivot moments after liftoff, directing the launcher on an easterly trajectory over the Pacific Ocean.

The H-2A will exceed the speed of sound in less than a minute, then the two solid rocket boosters will consume all their pre-packed propellant at T+plus 1 minute, 38 seconds. Ten seconds later, the boosters will fall away from the H-2A’s foam-covered core stage.

The two halves of the rocket’s clamshell-like nose cone will peel away at an altitude of 88 miles (142 kilometers) at T+plus 4 minutes, 5 seconds, revealing the Himawari 9 satellite to the space environment.

The LE-7A main engine, producing nearly 250,000 pounds of thrust, will shut down at T+plus 6 minutes, 36 seconds, after reaching a velocity of nearly 11,000 mph (4.9 kilometers per second).

Eight seconds later, the first stage and second stage will separate, followed by ignition of the upper stage’s hydrogen-fueled LE-5B engine at T+plus 6 minutes, 50 seconds. The powerplant will burn until T+plus 12 minutes, 12 seconds, to reach a preliminary low-altitude parking orbit, and then start up again at T+plus 23 minutes, 50 seconds, to climb to higher altitude.

The second LE-5B engine burn should end at T+plus 27 minutes, 7 seconds, after injecting the 7,700-pound (3,500 kilogram) Himawari 9 satellite into its intended orbit.

Deployment of Himawari 9 should occur at T+plus 27 minutes, 57 seconds, around 163 miles (263 kilometers) over the Pacific Ocean southeast of Hawaii.

Artist's concept of the Himawari 8 and 9 satellites in orbit. Credit: MELCO
Artist’s concept of the Himawari 8 and 9 satellites in orbit. Credit: MELCO

Built by Mitsubishi Electric Corp., Himawari 9 will maneuver into a circular orbit nearly 22,300 miles (35,700 kilometers) over the equator a few weeks after launch.

At that altitude, the spacecraft’s orbital velocity will match the rate of Earth’s rotation, allowing it to hover over Asia and the Pacific Ocean to collect real-time views of clouds and storms over the Eastern Hemisphere.

Himawari 9 will be parked at 140 degrees east longitude for a mission expected to last up to 15 years. It is Japan’s ninth geostationary weather observatory since the first satellite in the Himawari, or sunflower, series launched in 1977.

Japan launched the identical Himawari 8 weather satellite in October 2014, and a successful launch of Himawari 9 will allow Japan’s weather agency to retire the last pair of meteorological satellites — dubbed MTSAT 1R and MTSAT 2 — that have been in space in 2005 and 2006.

Forecasters from India to Australia have been relying on Himawari 8’s imagery since it entered service in 2015.

Himawari 8 and 9 carry advanced U.S.-built imaging cameras supplied by Harris Corp. The imagers can observe Earth in 16 visible and near-infrared color bands, while the previous generation of Japanese weather satellites were sensitive to five bands.

The new satellites can take a full picture of East Asia and the Western Pacific every 10 minutes, an improvement over the half-hour update times available with Japan’s MTSAT weather satellites.

The spacecraft’s imager can take pictures of certain areas, such as all of Japan, at even faster refresh rates — every 2.5 minutes.

There are also improvements in resolution with the Himawari 8 and 9 satellites, allowing meteorologists to see finer details at the centers of typhoons and better resolve volcanic ash and smoke plumes, fog and low-lying clouds.

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