Source: Wikimedia Commons.

For decades, conspiracy theorists have argued that the military's top secret Area 51 testing grounds in Nevada is home to UFOs. This week, they're right.

Whether or not there are bona fide little green men wandering around Area 51 remains a question cloaked in mystery. But as to the UFOs, well, there does indeed appear to be a new unidentified flying object tooling around the secret military base.

According to industry analysts at Aviation Week, who've been studying financial reports and satellite photography of the grounds, defense contractor Northrop Grumman (NYSE:NOC) is currently conducting flight tests of a new stealth spy drone at Area 51. Dubbed the RQ-180, the robotic aircraft is believed to be built in a cranked kite design -- so that it would look sort of like this experimental General Dynamics (NYSE:GD) F-16XL, but bigger, probably without the tailfin, and with more elongated wings, sweeping forward at the tips:

F-16XL. Source: Wikimedia Commons.

AW thinks the new Northrop bird is also considerably bigger than the spy drone that preceded it, Lockheed Martin's (NYSE:LMT) RQ-170 Sentinel -- the so-called "Beast of Kandahar" that Iran brought down in 2011. To lend some perspective, if General Dynamics' F-16XL had a wingspan of 34 feet, and Lockheed's Sentinel measured 65 feet, then the new RQ-180 could be four times the size of the fighter jet, and twice as big as Lockheed's spyplane -- 130 feet tip to tip.

Schematics for Northrop's X-47B naval drone, also utilizing a cranked kite design. Source: Wikimedia Commons.

At that size, the RQ-180 should be capable of carrying the ordnance necessary to make it an unmanned stealth bomber. Indeed, AW says the plane could potentially run combat missions as well as ISR. However, reports indicate the plane is more likely destined for spy work, flying high and fast, and stealthily penetrating such hostile airspaces as North Korea, Iran, or -- more so than ever before -- China.

Military strategists have advocated building about 50 drones  capable of undertaking such missions, to support more conventional warfighters. The RQ-180 could potentially succeed Northrop's popular -- but incredibly unstealthy -- line of Global Hawk spy drones in this role.

What does it mean for investors?
Probably the most successful publicly traded company manufacturing drone aircraft, Northrop Grumman must constantly innovate if it's to stay ahead of its competition -- which includes both General Dynamics and Lockheed, of course, as privately owned General Atomics to boot. Luckily for Northrop's investors, though, the company is well compensated for its efforts.

After all, one of the things that first clued in AW to the possibility that there might be a new spy drone circling Area 51, was an unexplained $2 billion increase in the size of Northrop's defense orders backlog back in 2008. No one's saying for certain that this money will be going to Pentagon purchases of new RQ-180 spy drones -- to the contrary, the Air Force's only official statement on the matter is that "The Air Force does not discuss this program."

But I think we can guess. This is one mystery you needn't be a conspiracy theorist to solve.