Japan plans to launch its first unmanned space probe to Venus in 2007, with the probe expected to begin orbiting the planet in 2009, according to project members at the Institute of Space and Astronautical Science.

The ISAS expects to start full preparations for launching the domestic M-5 rocket in fiscal 2002, following endorsement of the plan on May 10, the members said.

While Mars has attracted popular attention with speculation over possible life on the planet, only the United States and the former Soviet Union have sent probes to Venus.

Although the U.S. and Europe are also planning Venus explorations, Japan's scheme is the only to focus on the planet's atmosphere, the members said.

Venus' atmosphere consists mainly of carbon dioxide, and a greenhouse effect causes temperatures of up to 470 C.

No surface features on the planet are older than 300 million years, and some geographical configurations are believed to have been formed by volcanic activity.

The atmosphere rotates in the same direction as the planet, but up to 60 times faster. Venus completes a rotation every 243 days.

But the detailed mechanism of the planet's atmosphere, including its rapid air currents, is not well understood, as it is 90 times more dense than Earth's atmosphere.

According to the project members, the ISAS probe will be equipped with a camera that uses a special kind of infrared radiation that can penetrate the dense atmosphere.

The probe will take pictures analyzing the three-dimensional structure of the planet's atmosphere and its rapid rotations.

The probe will also check for active volcanoes on the planet.

Koichiro Oyama, who heads the project, said: "Earth may become a planet like Venus if global warming continues. If we find out the process of the evolution of Venus, it will be an important key to predicting the future of Earth."