2010年9月13日 星期一

Japan Launches Its First GPS Satellite

Japan Launches Its First GPS Satellite


Japan launched on Saturday the first of a planned series of satellites that promise to improve the accuracy of satellite navigation services in the country.

The "Michibiki" satellite was sent into space atop a Japanese H-IIA rocket from the country's Tanegashima Space Center at 8:17 pm local time on Saturday. The satellite later deployed its solar panels to complete a successful launch, the Japan Aerospace Exploration Agency said on Sunday.

Michibiki is the first in a planned series of three satellites that will provide navigation signals focused on the Japanese islands. Key to their mission is a figure-of-eight orbit that will see them make a tight northern swing over Japan and a much broader southern pass over Australia. This "quasi-zenith" orbit gave the project its name: Quasi-Zenith Satellite System (QZSS).

The orbit has been designed so that one of the planned three QZSS satellites is always in the skies above Japan. Because it will be almost directly above the country its signals should be able to reach many city-center streets and country areas that are sometimes out of the range of global positioning satellites because of skyscrapers or mountains.

The satellites will also broadcast a signal correcting any errors in GPS data so that positioning services can be delivered with more accuracy.

The signals are intended to be compatible with those broadcast by existing satellites so should work with current navigation equipment without modification.

Japan's QZSS system is one of a number of satellite positioning networks planned or under construction by countries eager to reduce their reliance on the U.S.-built and controlled NAVSTAR GPS network.

With satellite navigation playing an increasingly important part in safety systems and commerce, its importance to national economies has risen, thus the wish of some countries to have control over a system of their own.

Launch of satellites for two of the biggest networks, Russia's GLONASS and the European Union's Galileo, are already under way. China has plans to turn its regional COMPASS network into a global system and India has also announced plans to build a service.

Martyn Williams covers Japan and general technology breaking news for The IDG News Service. Follow Martyn on Twitter at @martyn_williams. Martyn's e-mail address is martyn_williams@idg.com

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