Nothing gets conspiracy theorists going like a top secret military space mission with an 'X' in the title.
Last week, the U.S. Air Force's mysterious X-37B space plane landed at the Vandenburg Air Force Base in California. The unmanned, reusable space vehicle managed to clock up a record breaking 675 days in space - the longest known space flight for any man-made vehicle which has subsequently returned to Earth in one piece.
The X-37B Orbital Test Vehicle is a modified version of NASA's X-37 design, although NASA has seemingly taken a back seat in this endeavor. Instead it's being headed by the Air Force Space Command (AFSPC) and Defense Advanced Research Projects Agency (DARPA) - both military entities. The X-37B's most recent mission, titled OTV-3, is its third trip into space. On its previous two missions it also clocked up an additional 225 and 469 days in space, respectively.
The Official Explanation
Considering its military connections, the exact objectives of the OTV-3 are classified, although the air force has released some information claiming the X-37B was being used to test space flight technology. Official sources claimed it was experimenting with "advanced guidance, navigation and control, thermal protection systems, avionics, high temperature structures and seals, conformal reusable insulation, lightweight electromechanical flight systems, and autonomous orbital flight, reentry and landing."
Later, the air force also added the objectives of the X-37B were to develop "reusable spacecraft technologies for America's future in space and operating experiments which can be returned to, and examined, on Earth."
However, this official statement hasn't placated conspiracy theorists, who believe the X-37B has been up to no good in space. Here are some of the major theories concerning what that plucky, enigmatic space ship has been doing up there the whole time.
Some claim the X-37B could be being used as a more mobile and versatile spy satellite, while others have suggested it was also used to spy on China's Tiangong-1 space station. Although this might make sense to the laymen, the theory has been put to rest by experts. Concerning spying on Tiangong-1, space analyst Jim Oberg told the BBC it was impossible. He explained:
They are in orbits which cross the equator about 90 degrees apart. They crisscross each others' paths at thousands of meters per second. Any observation from one to the other is impossible.
Others also noted that the X-37B spent a lot of time hanging around the Middle East, Asia Minor and North Africa. This led some to speculate it was testing prototype surveillance technology. This seems to make more sense than spying on Tiangong-1, but the advantages of using a vehicle which has fuel requirements over, say a traditional satellite, is not immediately clear.
A Prototype Space Fighter
Others have speculated that the X-37B could the forerunner of a fully-fledged Star Wars-esque space fighter or orbital bomber. The ship is certainly smaller than traditional shuttles - it only has a 15 foot wingspan - while the fact it is automated means it can essentially provide a constant patrol of space without the need for trained astronauts.
But, once again experts have suggested this seems unlikely. Firstly, University of Maryland professor and former Air Force chief scientist, Mark Lewis, claims the vehicle's limited fuel supply and requirement to spend long periods recharging via solar panels would make it a bomber of limited value. As a result, using the X-37B in this role doesn't really offer many advantages over ballistic missiles or high altitude bombers. Theoretically, it could be used to deliver nuclear weapons, although this is outlawed by the Outer Space Treaty.
A more probable military application could be to knock out enemy global positioning, communication and surveillance satellites in times of war. However, this is something the US and other nations are already able to do with ground-based missiles. Back in 2008, the US military conducted Operation Burnt Frost, a quasi-experiment which saw them shooting down a non-functioning reconnaissance satellite with a RIM-161 anti-ballistic missile. Using the X-47B would be a more expensive, and more easily trackable, method of doing just this.
What's in the Cargo Bay?
The X-37B comes with a rather small cargo bay - about 7 feet by 4 feet. Some of the more 'out-there' conspiracy theorists have noticed this is roughly the size of an adult human. Given the length of time the ship was in space, plus its requirement to return again, this has led some to speculate that the X-47B could be housing an experiment into suspended animation.
Experiments into suspended animation have been attempted, but never on humans. One line of thought suggests freezing humans like a giant pork chop could increase the longevity of a human life, however currently it is impossible to defrost a human without irreparably damaging the body's cells. Another method involves draining the individual of blood and replacing it with a chilled saline solution which keeps the body alive in stasis. This method has reportedly been attempted on dogs and pigs with successful results, although only for a matter of hours.
Personally, the fact we even know the size of the X-37B's cargo bay size perhaps suggests this experiment isn't really as secret as our Hollywood-addled brains would like us to think. With this in mind, the official explanation from the Air Force does seem pretty reasonable to me. Of course, the big question is what they intend to do with the results of the X-37B experiments...
What do you think the X-37B was up to?
What do you think the X-37B has been doing?