A newly declassified U.S. government report confirms the existence of a secret base in Nevada known as “Area 51” – but, unfortunately for UFO enthusiasts, there’s no mention of aliens.

In some wilder accounts of Area 51, the base serves as a repository for crashed UFOs and recovered alien bodies. The government’s version of the story is a little less dramatic.

In a 400-page report from 1992 titled “Central Intelligence Agency and Overhead Reconnaissance: The U-2 and Oxcart Programs, 1954-1974,” historians Gregory Pedlow and Donald Welzenbach detail the history of Area 51 as a testing site for the experimental U-2 military airplane. The U-2 plane flew much higher than commercial and military aircraft at the time, allowing the U.S. military to spy much more effectively on the Soviet Union and its allies during the Cold War.

In 1955, while surveying for testing sites in Nevada, a group of men working on the U-2 project spotted an old unpaved air strip next to a salt flat known as Groom Lake that proved isolated enough for their needs. A little rectangular bit of wasteland, known as Area 51 on the maps, was added to the test site.

“To make the new facility in the middle of nowhere sound more attractive to his workers, [Lockheed Martin engineer] Kelly Johnson called it the Paradise Ranch, which was soon shortened to the Ranch,” Pedlow and Welzenbach wrote.

U-2’s flew at above 60,000 feet, while commercial airliners in the 1950s and 1960s typically operated between 10,000 and 20,000 feet. One unexpected consequence of the U-2 test runs was an increase in reports of unidentified flying objects, the report says.

UFO reports from airline pilots were much more likely to come in the early evening hours on east-to-west flights. At that time, the U-2 was in the right position for its wings to catch and reflect sunlight, creating the appearance of fiery objects in the sky. Sometimes, sunlight bouncing off the U-2’s body created glints or reflections that could even be seen on the ground, according to Pedlow and Welzenbach.

Air Force officials, bound to keep the U-2 and later OXCART projects secret, tried to explain the UFO sightings by “linking them to natural phenomena,” the report says.

The report was obtained by George Washington University’s National Security archive, through a Freedom of Information Act request, according to ABC News.

Some parts of the report are still redacted. The U.S. military was initially interested in hiring foreign pilots for U-2 tests; if the plane was shot down in hostile territory, it would be easier for the U.S. to deny its involvement. The names of the countries these foreign pilots hailed from is redacted from the released version of the report. At any rate, language barriers and a lack of experience with heavy aircraft on the part of the foreign pilots forced the Air Force to recruit U.S. citizens in the end.

The report also makes mention of three fatal crashes during U-2 test flights in 1956. Wilburn S. Rose crashed in May after he had trouble dropping his “pogos,” the wheels that kept the U-2’s wings parallel to the ground during takeoff. When he tried to shake one of the wheels loose, the plane stalled and crashed. Another accident in August 1956 occurred after pilot Frank G. Grace sent the plane climbing up too steeply at takeoff. Another U-2 crashed shortly after takeoff in September 1956, but this accident occurred at an Air Force base in Germany.

While the new report adds further information to the history books, it probably won’t completely squash the conspiracy theorists.