How did Satellites...

[INRM]

Transmit photos in the old days?

In the old days, satellite photos were often developed, and then blown-up to make them large enough to gather intel. The question is, how'd the film get down to earth from a satellite orbiting some thousands of miles up in space...

-INRM

 

[Soapy Sam]

I believe some spy sats actually re-entered, deployed parachutes and were recovered, but a large format pic could be radioed down, one scan line at a time, just like the old photos were wired to newspapers. There must be plenty of ways.

 

[thinkren]

I believe the Corona program was the first of its kind to do the sort of thing you are wondering about.

click here for a good run down (with pretty pictures too!) of what it was and how it was done.

 

[Crossbow]

In the US, the satellites took photos with film that was put into canisters which were then sent back to Earth. Once they re-entered the atmosphere, a parachute would be deployed and the photos would be recovered while in air, then the film would be processed as the plane was heading back to its base. I think one canister held about two weeks worth of photos and there were eight canisters per satellite.

Originally, they wanted to have a system on the satellite that would develop the photos, then scan them, then transmit the images back to Earth. However, the techonolgy was simply not available at the time, so they went for this simpler solution.

 

[aggle_rithm]

The old days

Neanderthals used to throw rocks at the satellite until it fell to the ground, where they could easily retrieve the photographs.

Since they didn't have photo paper in those days, they had to place the images on cave walls.