If you had a difficult time trying to get into the website that posted Area 51 images earlier this week, there was a good reason.

Terraserver.com has been invaded by an alien being.

A computer hacker broke into the site and disrupted service for more than 36 hours, the company said in a statement Thursday.

"The terraserver.com website was attacked within six hours of the release of the imagery," Chairman John Hoffman said.

The company released the images the previous day to news organizations, including SPACE.com. For the next few days, the website was overwhelmed with an estimated 3 million "page views," compared with the normal usage of 700,000 to 800,000 per day. The hack job eventually shut down operations completely.

"The site has been fielding 10 times its normal volume of traffic since the release of the Area 51 images," Hoffman said.

Federal authorities are investigating the cyber assault and the site is now up and running.

"We are cooperating with authorities who have confirmed the attack and are investigating it," Hoffman said.

The 6.5-foot (2-meter) images were captured on March 15, 1998, by the Russian Kometa satellite. The images show views of the Nellis Air Force base and Nevada Proving Grounds. Included in these images are Groom Lake, the Nevada Nuclear Test Site and the sector commonly known as Area 51.

The area -- 75 miles (121 kilometers) northwest of Las Vegas -- was named after the grid it occupies on an old Nevada map. It came into existence in 1955 when Lockheed landed there to test the U 2, a high-altitude surveillance plane.

The top-secret base later became a proving ground for several generations of high-tech prototypes, including the F 117-A Stealth fighter.

Ufologists have long believed that unidentified flying objects from other planets are entrenched in underground bases in the region and insist alien autopsies are conducted there. But conventional wisdom says the base is more likely a center for super-secret operations dealing with sophisticated military aircraft.