Fifty firefighters were dispatched to Mount Graham International Observatory, where, in an attempt to protect it, they ignited controlled fires to burn off dry vegetation. Tankers brought water to the mountaintop observatory to drench the area.

High temperatures and strong winds complicated the task of killing two blazes that have already consumed 65,000 square kilometers (25,000 square miles) of land. Authorities fear the two fires could merge.

"We're not out of the woods yet," said Buddy Powell, director of observatory. "This is still a very critical and dangerous time for us. We're preparing for the worst, but hoping for the best."

The observatory complex is home to eight telescopes, including the University of Arizona's 110-million-dollar Large Binocular Telescope, which will become the world's most powerful when it is completed in 2007.

Its images are expected to be 10 times sharper than those from the orbiting Hubble Space Telescope.

German and Italian institutes are among the observatory's partners.

"Arizona for the last 50 years has been a world-renowned spot for astronomy, particularly southern Arizona, because of the dry skies, lack of clouds and lack of light pollution."

The two wildfires were sparked by lightning strikes that hit Arizona's dry forest, which has suffered from a long drought.

TERRA.WIRE