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When I look at pictures taken by a modern spacecraft (like that one showing the surface of Titan:

Titan

and taken by Cassini) I kinda understand how they might be produced. There might be some kind of CCD sensor installed and the data is later transmitted to Earth.

But then I think about it I start to wonder how cameras worked on older spacecrafts like Mariner, for example this one taken by Viking 1

Mars.

As far as I know there were no digital cameras back then. How did they get around it and were able to produce photos and more importantly sent imaging data back to Earth?

I can imagine that there was an analog camera installed along with some scanning facility but that sounds sooo unlikely as it would require a rather complex machinery which isn't feasible for an operation in space. But other than that I'm out of ideas. Wikipedia is surprisingly silent about it, too.

EDIT: Thanks, everybody, for your great answers! I upvoted everything I could and accepted Georg's answer for a great Wiki link.

Community
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Andrei Андрей Листочкин
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3 Answers3

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There were a lot of (TV) Cameras from the first Ikonoskops (by Zworykin) in the 30ties up to Orthicons or Plumbicons and what -cons ever were invented. Just google for that names.

PS The word "digital" is misused a lot today. The CCDs are not digital, there is some analog/digital stage coupled to the CCD or maybe "onboard" the CCD chip. But nevertheless the CCD works analog.

Georg
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  • Well they are digital upto the output amp (1 photon = 1 electron) and with science CCD cameras you have readout noise of 1 electron so digital-ish – Martin Beckett Apr 01 '11 at 16:48
  • @Martin, then read about working principle of all those -trons. Most (All?) of them were digital-ish from beginning by Your definition. (1 photon = 1 electron) – Georg Apr 01 '11 at 16:53
  • that was interesting I didn't realise that Vidicons actualy stored an image - I thought it was purely a scanned photo-conductor thing. And that the predecessors to vidicons were a lot like the intensified - Image Photon Counting Systems that competed with CCDS when I started doing astronomy cameras – Martin Beckett Apr 01 '11 at 17:21
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    @Martin, You need either the charge accumulation or some really high amplification as in a photomultiplier. The latter did not exist in the thirties and more important: optical scanning is mechanical demanding, heavy and voluminous. The ony exception I know were those tubes with a electron picture, amplified in channel array plates, then directed on a phosphor for direct wieving. (used in night vision equipment) – Georg Apr 01 '11 at 21:33
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    I knew they were electronically scanned, I just thought the e-beam measured the conductivity of the photocathode at each point at that time - ie the cathode was only biased at the point the beam was scanning . I didn't appreciate that there was an actual charge image on the plate. – Martin Beckett Apr 01 '11 at 21:37
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Viking1 used vidicons basically the same thing that studio TV cameras used into the 80s

Martin Beckett
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Others answered about the old cameras, but a piece of trivia about current space craft cameras to clarify a small misconception: the primary cameras used in the Mars landers (like Spirit and Opportunity) are high-resolution B&W cameras equipped with switchable color filters for R, G and B. The craft sends 3 b&w images filtered through the 3 filters and they only get composed into one color image by earth crew.

SF.
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  • Is this still done in that way? Separate filters can have a much higher quality compared to the "dots" on a CCD. So for stills this technology is perfered still today? – Georg Apr 01 '11 at 15:46
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    In science cameras yes - large multilayer filters a re much better than the colored dyes on a bayer mask and you can have as many bands as you want. And for commercial large format digital , at least for still life - you get the full image resolution for each color and no moire effects – Martin Beckett Apr 01 '11 at 16:46
  • The primary cameras on MSL (Curiosity) are "full colour" and use RGB Bayer pattern filters like those on Earthbound consumer digital cameras (though there is an array of additional filters available). – orome Sep 18 '12 at 14:38