"An H-2A rocket flew to space Saturday with a Japanese satellite to meet a pressing need for improved navigation services amid the country's numerous mountains and high-rise buildings.
"The rocket's payload is the first of three planned satellites to fill coverage gaps from U.S. Global Positioning System satellites caused by signal blockage from mountains and skyscrapers.
"Developed by the Japan Aerospace Exploration Agency and four government ministries, the Quasi-Zenith Satellite System is aimed at overcoming ground interference by launching more navigation satellites strategically positioned high in the sky above Asia.
"The line-of-sight navigation signals from GPS satellites can be interrupted in rural hamlets and skyscraper-filled cities like Tokyo, where users occasionally lack sufficient data to determine their position, elevation and time.
"JAXA says a constellation of three QZSS spacecraft would make three-dimensional navigation coverage available 99.8 percent of the time, an improvement over the estimated 90 percent availability with GPS satellites today.
"Four GPS satellites must appear in the sky at one time to triangulate a user's 3D position and time, but buildings and mountains can block signals from spacecraft close to the horizon.
"The first QZSS navigation craft launched Saturday on an H-2A rocket. Its nickname is Michibiki, which means "guiding" or "showing the way" in Japanese.
"Michibiki is demonstrating the system's navigation instruments and proving the satellite works before Japan commits to launching the other two spacecraft.
"The 17-story launcher lifted off at 1117 GMT (7:17 a.m. EDT) from Launch Pad No. 1 at the Yoshinobu launch complex, a shoreline facility at the Tanegashima Space Center off the coast of Kyushu, the southernmost of Japan's main islands."
"JAXA says Michibiki will reach its final orbit in about two weeks. It will be three months before the satellite finishes commissioning tests and can begin its navigation demos.
"Michibiki will circle the Earth at a 45-degree angle to the equator. Its orbital high point will be more than 24,000 miles [38,600 km] over the northern hemisphere and its lowest altitude will be 20,500 miles [33,000 km], according to JAXA.
"Projected against Earth's surface, Michibiki's ground track will chart an asymmetric figure-eight pattern stretching from Japan to Australia as it alternates north and south of the equator.
"Michibiki will be near-zenith, or almost straight up, in the Japanese sky for about eight hours each day. If launched, the two follow-on satellites would permit continuous coverage of Japan."
Source: Spaceflight Now, "Navigation satellite launched to show the way in Japan"
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