Agent Big Bird, the US Cold War spy satellite

During the Cold War the US deployed a series of iconic spy planes, such as the Blackbird. But these weren't the only weapons in the US spy arsenal. Watch this video to find out more.

The Cold War saw an unprecented level of spying by the USA and the Soviet Union. While much of it was carried out by long-range spy planes such as the SR-71 Blackbird, there were other methods - one of which was beyond the reach of any air defence missile.

You could call it a Cold War equivalent to Google Earth - the spy satellite Hexagon, also known as Big Bird.

Video script: Ed Barrett, from the Department of Science and Technology Studies, University College London.