Some scenes in this series use recreated sound effects.

This is a hexagon reconnaissance satellite, and this was developed in the late 1960s.

At the National Museum of the U.S. Air Force, you can stand underneath a monster of a satellite.

This is a really big satellite.

It's the size of a school bus.

Dwayne Day is a space historian and a walking encyclopedia on the US military space program.

I remember a friend of mine, he had seen one of the early ones in the 1970s and he told me that it reminded

him of a locomotive. It has a cylindrical section at the back, which was where the rocket

motor was located and they used that rocket to re-boost it as it sank down in orbit.

It's called the KH9 hexagon, also known as the big bird.

This isn't any ordinary satellite.

This one was used to gather intelligence.

Its story goes back to the 1970s when the Cold War was at its height, a time when space

was a potential new battlefront.

And in the middle, it has two powerful cameras, and the cameras would swing back and forth

and would record large portions of territory below on film that went through the satellite

at very high speed.

Hexigan's cameras would grab images of the land below it,

not digitally as we do today, but on analog photographic film.

That showed what the Soviet Union was doing,

where their aircraft were deployed,

where their armies were in the field and

...