October 28, 2021

Japanese data relay satellite launches on H-2A rocket


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EDITOR’S NOTE: Updated at 5 a.m. EST (1000 GMT) after confirmation of a successful launch.

A Japanese H-2A rocket lifts off from the Tanegashima Space Center on Sunday. Credit: MHI

A Japanese satellite designed to relay data and imagery from civilian and military Earth observation spacecraft launched Sunday aboard an H-2A rocket.

The dual-use communications satellite rode an H-2A rocket into orbit at 2:25 a.m. EST (0725 GMT; 4:25 p.m. Japan Standard Time) from the Tanegashima Space Center in southern Japan.

A live video feed from media spectators at Tanegashima showed the 174-foot-tall (53-meter) H-2A rocket soaring into broken clouds over the spaceport.

The Japan Aerospace Exploration Agency did not provide a live webcast of the launch Sunday, likely due to the sensitive military connection with the data relay payload. Japanese officials have also not disclosed the new satellite’s exact operating position in geostationary orbit, or specifications on its mass and size.

Powered by a hydrogen-fueled LE-7A main engine and two strap-on solid rocket boosters, the H-2A launcher climbed into the stratosphere with 1.4 million pounds of thrust as the rocket headed east from Tanegashima over the Pacific Ocean.

The twin strap-on boosters burned out and jettisoned from the H-2A launcher less than two minutes after liftoff.

The H-2A’s core engine shut down and the first stage separated about six-and-a-half minutes into the mission, leaving the cryogenic upper stage to perform firings to place the data relay satellite into its targeted egg-shaped transfer orbit.

The rocket’s upper stage successfully deployed data relay satellite in orbit, according to Mitsubishi Heavy Industries, the H-2A rocket’s builder and launch operator.

Sunday’s launch was the 43rd flight of an H-2A rocket since 2001, and Japan’s fourth space launch of the year.

The H-2A rocket was expected to release its payload — part of the Japan Data Relay System, or JDRS — into an elliptical geostationary transfer orbit. The satellite will use its own propulsion system to reach a circular geostationary orbit more than 22,000 miles (nearly 36,000 kilometers) over the equator, where it will enter service and begin a 10-year mission.

At that altitude, the satellite will orbit at the same rate of Earth’s rotation, giving it a continuous view over the Asia-Pacific region.

The new satellite carries the Laser Utilizing Communication System, or LUCAS, payload developed by the Japan Aerospace Exploration Agency. From its perch in geostationary orbit, the optical communication payload will connect with satellites flying several hundred miles above Earth with a near-infrared laser beam, allowing the transmission of data at high rates.

Artist’s concept of Japan’s optical data relay satellite. Credit: JAXA

A single data relay satellite can communicate with a user spacecraft for about 40 minutes on each orbit, relaying imagery, scientific data, and other information between the Earth observation satellite and a ground station. The connection allows imagery analysts to more rapidly receive data than if they waited for the observation satellite to pass over an antenna on the ground.

The new optical data relay satellite replaces JAXA’s Kodama spacecraft, which had S-band and Ka-band inter-satellite links providing communication speeds of about 240 megabits per second. JAXA decommissioned the Kodama satellite in 2017 after a 15-year mission.

The laser-equipped relay satellite will permit data transmission speeds up 1.8 gigabits per second, more than seven times faster than the speeds possible with Kodama. The antenna for Kodama’s radio frequency transmissions had a diameter of 11.8 feet, or 3.6 meters, while the laser terminal for the optical relay satellite has a diameter of 5.5 inches, or 14 centimeters.

JAXA launched an experimental test satellite named Kirari in 2005 to demonstrate inter-satellite laser communication links.

“Using this as a foothold, LUCAS was developed to achieve high reliability, miniaturization, and significant improvement in communication capacity for practical use,” JAXA said.

Designed for a 10-year mission, the new optical data relay satellite will serve Japanese civilian-operated Earth observation satellites and Japan’s fleet intelligence-gathering surveillance spacecraft spying on North Korea and other strategic points of interest.

Civilian satellites in development that are primed to use the new laser data relay station include Japan’s ALOS 3 and ALOS 4 land imaging observatories. Once launched, ALOS 3 and ALOS 4 will collect imagery to assist in disaster response, environmental monitoring, agriculture and forestry management, and urban infrastructure planning.

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Follow Stephen Clark on Twitter: @StephenClark1.


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