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I just saw a report on NASA TV that said that dSLR cameras are replaced every 12 to 18 months because of the large number of dead and hot pixels, but video cameras last much longer, and they were looking into why.

Since the digital image technology came from space and astronomy in the first place, sensors would be well understood for the environment. I don't recall any discussions ever concerning sensor degradation on the HST or on Mars.

Anyone know what is different?

  • Convection cooling in microgravity? – user35658 Jan 5 '15 at 5:49
  • Mars has both gravity and an atmosphere. Neither is near as strong as Earth's, but they are there. The ISS does have pressurized compartments, but there is no atmosphere for 60 miles in every direction protecting it from the radiation present in space. While the Van Allen belts around Earth do protect it at times, when its orbit gets near Earth's poles it is less protected. My guess is stray radiation and cosmic rays can affect the life of the sensors. – Michael C Jan 5 '15 at 7:35
  • Cameras in Mars orbit work well with high resolution. Lots of space cams must somehow be built differently than commercial camera chips. (so why not build a space-rated chip holder to take Canon/Nikon lenses ?! ) – JDługosz Jan 5 '15 at 12:21
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    @jdlugosz because a camera is more than just a chip holder! Using a DLSR is much more convenient than NASA designing their own cameras for astronauts to use. Photos taken with DSLRs are not part of core ISS missions, they are just supplementary, the same is not true of the Mars rover cameras etc. – Matt Grum Jan 5 '15 at 15:39
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    "but video cameras last much longer" <- do you have a reference? "sensors on satellites don't degrade as quickly" <- again, do you have a reference? It seems they do degrade, but would be much more expensive and much more trouble to replace. People come and go on the ISS and bringing a new DSLR every couple of years is not particularly costly (compared to full mission costs). That article I linked is precisely about sensor degradation on Hubble. – Szabolcs Jan 5 '15 at 17:44
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I know the Russian space pencil story is a myth, but I think some of the logic applies here.

If you're sending a camera millions of miles away for a multi-year mission, or into orbit where repairs are infrequent, it's worth designing something custom, with appropriate shielding and redundancy. For example, from a description of the Curiosity rover's MAHLI camera:

The camera head electronics are laid out as a single rigid-flex printed circuit board (PCB) with three rigid sections. The sections are sandwiched between housings that provide mechanical support and radiation shielding; the interconnecting flexible cables are enclosed in metal covers.

I can't find offhand how much this camera alone cost, but I wouldn't be surprised if it was a decent fraction of the $700 million that went into the rover (out of $2.5 billion for the mission overall).

If, on the other hand, you're sending something along with humans that need to be regularly rotated out, that would be a waste of money. The effort and expense would be huge, and because projects like that take years, the results would probably be disappointing compared to current-generation consumer products. That MAHLI camera — the highest resolution camera on the Curiosity rover — produces 1600×1200 (e.g., 2 megapixel) images.

And that's just thinking about the image quality. There's a lot more than that which goes into making a camera — from design ergonomics to softare. Even at $20k per pound to get a new DSLR body to the space station, better to just keep sending up the (top end) mass-market cameras. (And hey, a new camera every 12-18 months sounds like the same schedule a lot of enthusiast photographers follow in any case!) It's like simply using a perfectly functional pencil rather than spending millions on a custom solution.

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There are companies who have specialized in the production of these cameras, or, more generally, space-proof hardware. Personlly I don't know anything specifically about CCD sensor degredation in space, but a google search on this topic brings up lots of scholarly articles and a book. I think it is a field of active research with many companies competing with private research money, or funds from the military.

In any event, many instruments on board of spacecraft are one-off types of machines and are therefore extremely expensive.

For instance, for the OSIRIS cameras on board the ROSETTA spacecraft that is orbiting the comet 67P/Churyumov-Gerasimenko, a budget of ~100 Million Euros/Dollars has been allocated (most of it development cost, operating cost, and personnel costs I guess). OSIRIS comprises a wide-Angle and Narrow-Angle CCD camera. For the specifications of the two cameras, see this page:

http://www2.mps.mpg.de/de/projekte/rosetta/osiris/index_print.html

or this one, with similar content:

http://www.mps.mpg.de/1845506/OSIRIS

For an example of a radiation-hardened processor, see this wikipedia page

http://en.wikipedia.org/wiki/RAD750

which gives you lots of links to investigate further. These processors run at about 200Mhz, and cost around $200.000 a piece.

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    I started to write up an answer about my experience working on a satellite with cameras on it, but this is a good enough answer. We are using commercial off the shelf cameras for some things, but for the less common missions, we might contract for a unique sensor. This will only be done for special missions, not for a weather satellite where we would use a 'more complete' off the shelf system. – Jasmine Jan 5 '15 at 20:31

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