Shortly after midnight on May 1, 2011 two unusual helicopters carrying 25 U.S. Navy SEALs...
...descended on Osama bin Laden's compound in Abbottabad, Pakistan.
The heavily modified Sikorsky UH-60 Black Hawk helicopters were able to fly 200 km undetected from the Afghanistan border...
...with neighbors reporting that they didn't hear the helicopters until they were directly overhead.
Their existence might have remained secret had one of the helicopters not crash landed on the wall of the compound.
U.S. forces destroyed the crashed Black Hawk with explosives, but a portion of the tail section survived...
...revealing top secret stealth modifications stemming from a program that had supposedly been discontinued in 2006.
Blackstar is a rumored suborbital space plane project run by U.S. intelligence agencies in the 1980s and 1990s...
...and perhaps continuing today.
The project was supposedly designed so the U.S. could retain orbital reconnaissance capabilities jeopardized by the 1986 Challenger disaster.
It was a 2-stage orbital system which used a high-speed aircraft to ferry a small orbital vehicle to the edge of space...
...which would separate and enter orbit 300 miles (480 km) above Earth using a rocket motor.
The orbital vehicle would then conduct reconnaissance on materials that could be hidden from the paths of spy satellites.
Funded through the U.S. Air Force's classified budget, the Northrop Gruman RQ-180 is the most advanced unmanned aerial system ever developed.
Designed for intelligence, surveillance and reconnaissance missions behind enemy lines, the RQ-180 could enter operation by 2015.
According to official sources, the RQ-180 will carry active, electronically scanned array radar and passive electronic surveillance measures...
...allowing it to conduct penetrating surveillance previously carried out by the SR-71 Blackbird before its retirement in 1998.
Based on the the size of new testing hangars at Area 51, the RQ-180 could have a wingspan of more than 130 ft (39.6 m)...
...and designs of the existing RQ-170 suggest that the RQ-180 can fly for more than 24 hours at altitudes as high as 11 miles (17.7km).
Operated by the U.S. Air Force, the Boeing X-37B is a robotic space plane designed to test reusable space technologies...
...though its payload and actual mission remain classified.
The craft was originally developed by NASA as the X-40, but it was transferred to the military and became classified in 2004.
Launched atop an Atlas 5 rocket, the 29 ft (8.8 m) long X-37B is able to spend more than a year in orbit before gliding to Earth.
Theories about the X-37B's true purpose include it being a space bomber, a spy plane or an anti- satellite weapon
Development of the X37-B continues, with Boeing recently converting the former Space Shuttle hangar at the Kennedy Space Center...
...into a servicing facility for an entire fleet of the craft.
The name “Aurora” first appeared when it was inadvertently included in the 1985 U.S. budget...
...as a $455 million allocation for “black aircraft production” in 1987.
Claims of its existence are based on observations that the U.S. has the technology needed to build such a hypersonic craft...
...indicative of the pulse detonation engine it is thought to utilize.
...and by sightings of black triangular aircraft accompanied by the donuts-on-a-rope contrail...
Aurora is also linked to unusual sonic booms that were recorded at regular intervals...
...by U.S. Geological Survey sensors across Southern California...
...which were later analyzed by NASA experts and showed "something at 90,000 ft (27.4 km)” moving at “Mach 4 to Mach 5.2"
With sightings starting in the 1980s and continuing today, the Aurora rumors may encompass multiple top secret aircraft...
...including many that are yet to be revealed.