A recently revealed, formerly secret U.S. government program that studied unexplained aerial phenomena—more colloquially referred to as UFOs—came as a surprise to many when stories describing it appeared almost simultaneously in the New York Times and Politico.

The Pentagon’s project, called the Advanced Aviation Threat Identification Program, was reportedly established in 2007 to investigate unexplained aerial phenomena that appeared to be using novel propulsive, hovering, or otherwise advanced technologies. A 490-page report detailing the program’s findings supposedly exists, though it has not yet been released.

Some may think that the very existence of this project supports the idea that aliens are visiting us, but that’s not a logical conclusion. The undeniable truth is that observations of a puzzling nature certainly merit investigation, as long as it’s done scientifically. And this project is not even close to the first U.S. government-funded search for evidence of advanced intelligence—so far, to little effect.

Projects that began more than five decades ago and still continue to this day include efforts to evaluate bizarre sightings and exotic objects, scan the skies for signs of intelligent transmissions, and develop instruments capable of sniffing out signs of life on faraway worlds.

The fact that the government chose to spend some cash on a supposedly scientific look at UFOs—particularly as they could be crucially related to national security threats—really should be no surprise, says Seth Shostak, one of the SETI Institute’s senior alien hunters.

The Science of Alien Sightings Neil deGrasse Tyson and SETI astronomer Seth Shotsak talk about alien sightings and how aliens are portrayed in the media.

“The feds have long had an interest in UFOs, going back to the celebrity cases of the late 1940s—Roswell, anyone?” says Shostak. “Much of the motivation for this interest was the worry that the strange things being reported in the sky might be novel Soviet—or today, Russian or Chinese—aircraft.

“But even if you think that the interest had greater scope, that the government really wanted to know if our little planet was being visited by other beings, there’s little surprise in the fact that they’ve spent a modest amount of money investigating that possibility.” Indeed, roughly a third of the U.S. population believes that some of these bizarre phenomena are attributable to extraterrestrial visitors, he says.

The bigger problem, according to Shostak, is that the money shunted into the Pentagon program went primarily to a company founded by Robert Bigelow, a billionaire aerospace mogul whose company builds inflatable space modules and who has long believed in alien visitation. Initiated after conversations between Bigelow and then-Nevada senator Harry Reid, the program garnered at least $22 million in funding over five years (it’s not yet clear whether it survives under a different guise after its supposed termination in 2012).

Within the new stories are nuggets of curious information, including the supposed keeping of unearthly alloys at Bigelow’s facilities, and a video that reportedly shows an object spotted by two U.S. Navy pilots.

But the most that’s publicly known about the program’s findings is second-hand at best, coming from insiders relaying their impressions to reporters. Some, like Reid, claim there is compelling evidence that merits further investigation—but the details remain as elusive as the aliens.

“Objective description of any phenomena should be backed up by compelling evidence, and despite many decades of reports of various UFO and abduction phenomena, we don’t have such evidence,” says Andrew Siemion, director of the Berkeley SETI research center. “Moreover, astronomers spend their lives looking at the sky with a wide variety of telescopes and techniques, and we have never snapped a picture of [an unexplained] spaceship.”

Here are some of our previous and ongoing attempts to find out if, in fact, aliens are out there and whether we have been visited, starting with the heyday of such activities around the middle of the last century.

1947: Roswell (Project Mogul)

Easily the granddaddy of all UFO conspiracies, the Roswell incident is described by many as the catastrophic crash of an alien spaceship in the New Mexico desert, after which the U.S. government supposedly retrieved the spacecraft (and several aliens). In 1994, the Air Force released a report identifying the debris as belonging to “a once top-secret balloon operation, Project MOGUL, designed to monitor the atmosphere for evidence of Soviet nuclear tests.”

1948-1952: Projects Sign and Grudge

First Sign and then Grudge, these Air Force-funded projects were examinations of flying saucers and other reported unexplained phenomena, inspired both by the Cold War and a 1947 observation of nine “disk-shaped objects” over Washington state. According to the CIA, “GRUDGE officials found no evidence in UFO sightings of advanced foreign weapons design or development, and they concluded that UFOs did not threaten U.S. security. They recommended that the project be reduced in scope because the very existence of Air Force official interest encouraged people to believe in UFOs and contributed to a ’war hysteria’ atmosphere.”

1952-1969: Project Blue Book

A continuation of the previous two projects, Blue Book was the longest and most extensive known investigation of unexplained aerial happenings. Of the 12,618 reported sightings it investigated, most were ruled to be misidentified natural phenomena or aircraft (including early U-2 spy planes on test flights); 701 and remained unidentified. The report concluded that “No UFO reported, investigated, and evaluated by the Air Force has ever given any indication of threat to our national security; there has been no evidence submitted to or discovered by the Air Force that sightings categorized as ’unidentified’ represent technological developments or principles beyond the range of present-day scientific knowledge; there has been no evidence indicating the sightings categorized as ’unidentified’ are extraterrestrial vehicles.”

1960: Project Ozma

Funded by the National Science Foundation, a federal agency created in 1950, this $2,000 project was the first scientific search for signs of intelligent radio transmissions from other worlds. Using a telescope at the Green Bank Observatory, astronomer Frank Drake (yes, the reporter’s father) listened for radio transmissions coming from planets that could be orbiting the stars Tau Ceti and Epsilon Eridani, but the scans came up empty.

View Images An aerial view of the Pentagon. Photograph by Bill Clark, CQ Roll Call, Getty Images

1966-1968: University of Colorado UFO Project/Condon Committee

Funded by the Air Force, this project produced 1968’s Condon Report, which concluded that there was no compelling evidence for extraterrestrial involvement in UFOs, and which recommended discontinuing Project Blue Book and any further investigations of UFOs. The report inspired the American Association of the Advancement for Science to convene a meeting on the topic, which Carl Sagan and Thornton Page then turned into a book called UFOs: A Scientific Debate.

1970s and ‘80s: CIA Investigations of Paranormal and Psychic Phenomena

The 1970s and 1980s saw the CIA investigating a bunch of phenomena associated with UFO sightings, such as parapsychology and psychic happenings. According to CIA report “Role in the Study of UFOs, 1947-90 (A Die-Hard Issue)”, “CIA officials also looked at the UFO problem to determine what UFO sightings might tell them about Soviet progress in rockets and missiles and reviewed its counterintelligence aspects.”

1976-1993: SETI/HRMS

The only time the search for extraterrestrial intelligence, or SETI, has been written into a NASA budget line, this decade provided as much as $12 million a year for searches using the Arecibo and Goldstone antennas. Around 1990, the government’s SETI program—headquartered at NASA’s Ames Research Center—was renamed the High Resolution Microwave Survey in an attempt to avoid cancellation. Nevada senator Richard Bryan ended up cancelling the program anyway in 1993, right after actual observations had started.

1990s to now: NASA’s Astrobiology Institute

Founded in 1998, the NASA Astrobiology Institute is one of many projects within the space agency aimed at investigating the possibility that life exists elsewhere in the cosmos. Scientists under its umbrella are currently thinking about whether life once existed on Mars, if there might be organisms tucked beneath the icy shells of the moons Europa and Enceladus, and how we would even recognize what life beyond Earth looks like if and when we see it.

Now, and beyond