Japanese H-2A rocket ready for launch with navigation satellite – Spaceflight Now


A Japanese H-2A rocket is heading towards its launch pad at the Tanegashima Space Center with the QZS 1R satellite. Credit: MHI

Japan is set to launch a replacement satellite for a navigation spacecraft that has been in space since 2010 on Monday, augmenting the US military’s GPS network to provide more accurate positioning and timing services to the region. Asia Pacific.

The new satellite will join the Japanese Quasi-Zenith satellite system, or QZSS, which allows users to better estimate their position, especially in cities and remote areas, where skyscrapers, trees and mountains can block the views. signals from GPS satellites.

A Japanese H-2A rocket is ready to deploy the new satellite, named QZS 1R or Michibiki 1R, to replace the first Michibiki spacecraft launched during a previous H-2A flight in September 2010. The QZS 1 satellite has exceeded its 10 years of origin. design life.

Liftoff of the 174-foot-tall (53-meter) H-2A rocket from the Tanegashima Space Center in southwestern Japan is scheduled for a 15-minute window opening at 10:19:37 p.m. EDT Monday (0219 GMT; 11:19 a.m. ). Japan Standard Time on Tuesday).

The flight was delayed for 24 hours due to poor weather forecasts for the first opportunity to launch the mission.

Japanese teams from Mitsubishi Heavy Industries, the main contractor and operator of the H-2A, rolled the rocket from its assembly building to the launch pad about 15 hours before takeoff. The 1,600-foot (500-meter) journey on a mobile launch table took approximately 30 minutes.

Once on the launch pad, the rocket was connected to ground-based electrical and thruster systems, allowing the H-2A team to begin loading liquid hydrogen and liquid oxygen into the tanks of the first and second stages of the launcher.

QZS 1R, built by Mitsubishi Electric Corp., weighs approximately 4 metric tons (4.4 tons) fully powered atop the H-2A rocket.

The H-2A rocket is equipped with two solid strap rocket thrusters, providing the majority of the 1.4 million pounds of thrust to push the launcher off the platform.

A hydrogen-powered LE-7A cryogenic main engine powers the center stage, and another cryogenic engine – the LE-5B – is mounted on the second stage of the rocket.

Heading east after takeoff from Tanegashima, the rocket’s strap thrusters will consume their thruster in about two minutes before jettisoning and falling into the Pacific Ocean. The middle floor, covered with a blanket of orange foam insulation, will burn for about six and a half minutes.

Then, the upper stage LE-5B engine will fire for two maneuvers to inject the QZS 1R satellite into an elliptical transfer orbit extending over 22,000 miles (approximately 36,000 kilometers) above of the earth. Deployment of the spacecraft is expected approximately 28 minutes after takeoff.

The QZS 1R satellite during pre-launch tests. Credit: Cabinet Office du Japon

Designed for a 15-year lifespan, the spacecraft will use its own propulsion system to achieve a near-circular geosynchronous orbit with an average altitude of around 22,000 miles. The QZS 1R satellite will set up in an operational orbit tilted between 40 and 45 degrees from the equator, where it will circle the planet once every 24 hours.

The fleet of four QZSS satellites, fully compatible with the GPS network, is positioned in orbits that roam over Japan. GPS satellites, operated by the US Space Force, revolve around the Earth in lower orbits, which means that different spacecraft are visible in the sky at different times.

Projected against the surface of the Earth, the ground track of the QZS 1R satellite will trace an asymmetric figure-eight pattern extending from Japan to Australia, alternating north and south of the equator. Three of the active near-zenithal satellites are positioned in similar inclined geosynchronous orbits, and one is stationed in geostationary orbit above the equator, remaining in a fixed position above the planet.

Like the satellite it replaces, QZS 1R will be near zenith, or nearly upright, in the Japanese sky for about eight hours each day. With a full set of satellites, the constellation allows continuous coverage of Japan.

Michibiki means “to guide” or “to show the way” in Japanese.

It takes four GPS satellites to calculate an accurate position on Earth, but a Michibiki satellite broadcasting the same L-band signals will give the receiver an estimate if there aren’t enough visible GPS satellites, or it can help produce a more accurate position calculation even with full GPS service.

Japan is developing three more near-zenith navigation satellites to be launched by the end of 2023. The expanded fleet of seven spacecraft will provide Japan with full navigation coverage in Japanese territory, regardless of any GPS signal.

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