Japan has launched a satellite to improve car navigation and other services using the Global Positioning System.

The Japan Aerospace Exploration Agency launched the quasi-zenith satellite Michibiki on Saturday from the Tanegashima Space Center in Kagoshima Prefecture, using an H2A rocket.

The 4-ton Michibiki -- 3 meters long, 3 meters wide and 6 meters high -- is intended to boost the accuracy and coverage of GPS services in Japan by complementing a US satellite network.

Japan's GPS services currently depend on US satellites.

But their orbits are not just above Japan and radio waves from those satellites can be hampered by skyscrapers or mountains.

The agency aims to eliminate such blind spots and reduce the margin of error to within 1 meter by putting the Michibiki on an orbit almost just above Japan.

But the Michibiki will be above Japan for eight hours a day. Two additional satellites are needed to provide 24-hour coverage.

The government has yet to have any specific launch plan for the additional satellites. It is expected to work out outline plans by next spring.

The government has so far earmarked about 40 billion yen as development costs for Michibiki and some 33.5 billion yen as ground facility and launch costs.