Yep, I'll have to differ with you on this.

It may look like colors from sub-surface life forms to some folks, but to me it looks like that under the iron impactor dust the sub-surface of Mars has the same color as the Moon.

For the most part the rocks look to me like impact expelled and then weathered gravitational conglomerates of earlier impact debris, with different compositions depending on their formation process, and different pitting depending on their time on the surface and exposure to other impacts.

It is fascinating how colors are linked with different classes of life forms, but the Viking color data are simply too weak to justify any claims, other than that under the iron dust Mars is pretty much the same color, wherever you go on the planet. I vaguely remember a Russian researcher also claiming signs of life detected in the optical bands from orbit, but once again the data was too weak.

While I think that there may be sub-surface life on Mars, I don't think they've got blue-green colored cyano-bacteria here. (And here I always thought cyano-bacteria required water and were red, like our red tide.) I think what they have are grey granite derviatives, for lack of a better geological description.

While we differ sharply on this, I think we both can agree that the Viking data needs to be re-processed using modern computer image processing techniques.

But anyway, thanks for the references, especially for the color/life form link.

EP