[bwr]

I'm guessing there is a lot of data that never gets sent to earth. Do they send thumbnails of the images to determine what is interesting? Is there a software tool available that creates a thumbnail and then creates a copy of the original image that is dependent on the thumbnail to be recreated. If you can't tell I wasn't really sure how to word that last sentence. Basically, less data would be required to transmit because you are only sending the data required to reconstitute the real image. Depending on the size of the thumbnail this might result in a negligible difference.

For example, a very naive implementation might create a thumbnail from every pixel where x or y is odd and then when/if you want the original image you can get the data required to put the image back together (it would be a similar sized thumbnail but with the even pixels) For this naive approach the thumbnail would likely be much larger than you want and would not help at all :)