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?
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.
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.
