The Black Vault makes it easy to search nearly 130,000 pages of declassified documents from Project Blue Book, the U.S. government's investigation of UFOs from the 1940s through the 1960s. Covering everything from sightings to possible evidence of alien contact on Earth, Project Blue Book features some amazing stories and maybe not all the answers, Black Vault's John Greenewald said.

Project Blue Book started as an investigation in 1952 by the U.S. Air Force to analyze UFO sightings and activity. Thousands of reports were collected and the investigation concluded there was no evidence of UFOs visiting Earth with many of the sightings linked to weather balloons, natural phenomena or misidentified aircraft. Project Blue Book was shut down in 1969 and the information is available to the public via Freedom of Information Act requests.

And that's what Greenewald did: 5,000 requests to be exact. The request brought in thousands of documents and he spent 22 years converting the files into PDFs to create a searchable database. Looking through all the documents, Greenewald does not reach the same conclusion as the government.

"Blue Book was never a true investigation, but rather it was an explanation. During the late '40s and the 1950s, the military and the government knew they had to calm the public down about the hysteria of the UFO phenomena, and I believe Blue Book was more of that [public relations] campaign. Where Joe Blow would say he saw a UFO over wherever he was and the Air Force could say, 'Well, that's just a weather balloon,'" Greenewald said.

"But when you look at the documents, and you look at Project Blue Book and see what's there, but you add that to what else has come out through the Freedom of Information Act, to me, that's the bigger story. That's the bigger piece of evidence, to show that the UFO phenomena was not a case closed to the military and the government after 1969."

Looking over the Blue Book documents, Greenewald said the government took UFOs very seriously and considered them a threat based on sightings over the White House or nuclear facilities. Military and government officials also submitted UFO reports. "For decades thereafter [the end of Blue Book], there were UFO record after UFO record generated by the intelligence community. The CIA, the NSA [National Security Agency], the DIA [Defense Intelligence Agency] -- they all had records on this topic," Greenewald said.

While Greenewald has not had any strange encounters after filing the FOIA requests, he did have to wait more than 13 years for one document. He also had an interesting encounter with the NSA when he requested its UFO investigation files. "I received a couple hundred pages that were whited-out, to take away from that visual impact of blacked out information. Only three words per page were readable. You thumb through these things and you go, 'Wow, these really are top secret.' So, we know UFOs, whatever they are, are highly classified and, on top of that, they don't want us to know." When he asked for a Mandatory Declassification Review, the NSA said it did not have the original documents. "It just doesn't make any sense, but the NSA said they lost everything," Greenewald said.