NFL jerseys | louboutin | louboutin shoes | NFL jerseys cheap | coach handbags | jordan shoes |cheap jordan shoes

The grids of zigzagging white lines seen in two of the images — the strangest of the various desert structures — are spy satellite calibration targets. Satellite cameras focus on the grids, which measure approximately 0.65 miles wide by ugg boots cheap 1.15 miles long, and use them to orient themselves in space. [Gallery: Mysterious Structures In China's Gobi Desert] The existence of these calibration targets may seem suspicious or revelatory, but Hill said it really girls ugg boots isn't; China was already known to operate spy satellites, and many other countries (including the United States) do so as well. In fact, the U.S. also uses calibration targets. "An example I found just now is a calibration target for the Corona spy satellites, built back in the 1960s, down in Casa Grande, Ariz.,