The New Horizons team released the following photo of Charon today
This choice of image seems rather odd to me for a number of reasons. First of all, according to Emily's schedule, there were 3 images slated to come down from Charon. These 3 images were chosen months ago, with some slight tweaks based off of the timing. LORRI is a square imaging camera. The fact that the image was rectangular seems odd to me. I've confirmed with the provided data that the height of this image is 1024 pixels, as expected from LORRI. However, the width appears to be about half that. What this tells me is that the right hand part of the image must have been deep space. Considering that every image released now is a contingency, it seems odd that the very edge of the moon is the area of focus, and even more that the moon was missed.
I've come up with a number of theories as to why this image is cut off, along with some thought behind them.
- The images could have been looking for dust or at the shadowed region. This seems unlikely because the exposure for such an image would have been different, and I doubt this would be a high priority image.
- The image was deliberately set for the edge of the moon, and it missed the mark slightly (About 1 field of view). This seems likely, but I'm not sure why the edge of the moon would be such a high priority image.
- The image was intended to be near the center of the moon, but missed the mark by quite a bit, barely capturing the edge of the moon. This is the one that has me the most fearful, hinting there is a chance that many of the best images could be missed because of some kind of a positioning error, which could be very bad.
- The 3 images were chosen of different parts of the moon (Center, middle, somewhere between?), and this was the one of the 3 deemed most interesting, again with a likely slight targeting miss.
- The predicted uncertainty was high. As a result, the 3 images were spaced well apart, to ensure the Moon was there. 3 images were downlinked, spaced in the uncertainty range such that there was a good chance Charon would be in the field of view. This one just happened to be on the edge, by coincidence.
- Part of the image was removed because the science team didn't want to include it, for some interesting science it holds. This seems to me to be very unlikely.
- Part of the image was cropped due to some significant artifacts that resulted from image compression/ dropped data. This one has some merit, as least as high as any other suggestion on here.
- Only part of the image was downloaded. This seems really unlikely, as all LORRI images we have seen so far are squares.
It's entirely possible none of these is correct as well. Bottom line, why was this image selected as one of the top 3 high resolution Charon images (As determined without knowing at all what Charon looked like), and why did so little of it come through in the image?