TOKYO (AP) - - A Japanese satellite orbiting the Earth will start mapping the sky in May after scientists fixed a glitch in the navigation system, an official said.

Japan launched the 13.4 billion yen (US$112.6 million; euro93.1 million) Infrared Astronomical Satellite on Feb. 22, and had planned to start mapping the sky using infrared wavelengths from mid-April.

But space officials soon found that they could not direct the satellite because a sensor used to track its position in relation to the sun was not working, said Japan Aerospace Exploration Agency spokesman Shinji Nagai.

The trouble was solved after officials adapted the navigation program to allow them to control the satellite using a second sensor, intended to recognize its position in relation to the Earth, Nagai said.

Observation and mapping will now start in mid-May, he said.

The one-ton ASTRO-F satellite was first developed by Britain, the United States and the Netherlands.

Its launch followed a string of successes for the Japanese space agency, also known as JAXA, which has struggled in the past.

It launched two H-2A rockets from the remote, southern island of Tanegashima in January and February this year, each carrying observation satellites.

Japan has said it will launch two spy satellites by March 2007 to monitor North Korea and other trouble spots — a program approved after North Korea launched a missile over Japan's main island in 1998.