(Image: © Google -  © 2011 Cnes/Spot Images, DigitalGlobe, GeoEye)
If you like puzzling over the meaning of the Nazca lines in southern Peru, crop circles in central England or poring over maps of Area 51, then you'll like this. Digital mapping fans today noticed some wild and wacky forms of indeterminate function in China's barren wastes in the Gobi desert.
The bizarre shapes vary widely. Two of them are grids that look a little like street floor plans without buildings and are around 2 kilometres long by just over a kilometre wide. Conspiracy theorists pounced immediately. Were these some sort of alien markings or the remains of a lost civilisation?
Slightly more likely is that it is being used to give China's upcoming spacecraft some kind of frame of reference. China's crewed Shenzhou 7 mission, launched in September 2008, released a small satellite that
orbited the crew capsule a few kilometres away: Japanese researchers believe it was testing a quantum key distribution system between the spacecraft and satellite. Could a ground-to-space system need some kind of elaborate ground sight?
Probably not. My money's on it being a target practice range for the People's Liberation Army.
Why? One of the other formations gives the game away: looking tantalisingly like Stonehenge from a great height, zooming in reveals three aircraft sitting at it's heart. Clearly, it is some kind of military target for airstrike or gunnery practice. Another 4 x 4 piece grid some 200 metres across has some pieces clearly blown to smithereens, again supporting the target practice theory, and a dummy runway in garish bluish-white is probably not for style-conscious aliens but air-to-ground strafing practice.
However, there is always the chance the Google maps have been hacked and that these "structures" are mere overlays, inserted through digital skulduggery and intended to keep conspiracy theorists happy for weeks. The 21st century version of crop circles, in other words.