Hi Silvercup,
OK - I have just spent an hour quickly acquainting myself with the Mars Express VMC Forum (
http://www.unmannedspaceflight.com/index.php?showtopic=5415) and my initial feeleing is that their basic RAW images should be capable of being deBayered here on PI - using any of the deBayer routines that have been produced (other than 'my' one, which will not work for RGBG or RGGB CFAs).
Nowhere on their Forum did I read about WHAT the exact CFA layout is - so I can't help there. Why nobody has described it I don't know. The guy who wrote the VMC2RGB routine is an obvious starting point. I believe that he may have written this in Java (?) so it might be an easy step for him to create a PJSR equivalent.
Looking quickly at what they are trying to achieve on that site, it becomes screamingly obvious that PixInsight would be a better option for a lot of the processing that they are trying to do.
If I get some spare time, I'll maybe try my hand at one of their RAW images, processing entirely in PI.
Cheers,