Thanks for all the comments. This was actual one of the simplest renders I've done in a very long time. First I downloaded the highest resolution mars surface map that I could find (8192 x 4096) which I then modified in photoshop to add some vibrancy, contrast and some sharpening to pull out some of the hidden features. This Image map I used as a shader for the colours and detail on the planet. I then took the same image and converted it into grayscale did some levels and curves work and used this as a displacement shader. The only other adjustments I made was to mess around with the atmosphere to get the look I wanted.
I downloaded the surface map here:
http://www.celestiamotherlode.net/Next steps are to begin figuring out how much powerfractal data is needed for various zoom levels to eventually create an animation zooming from planetary level down to surface level.
A screenshot of the embarrassingly simple node network is attached.
