Peter Ness wrote:
Mariner 9 took a series of daily photos of the Martian southern polar cap between November 1971 and October 1972 showing the summer retreat of the ice caps. Does anyone know how I can get access to these very useful images?

Alex writes:
The first stop for me is always the NSSDC. For Mariner 9 vidicon television photography data you may wish to visit

http://nssdc.gsfc.nasa.gov/database/MasterCatalog?sc=1971-051A&ds=*

and scroll down towards the bottom of the page.

Peter Ness wrote:
However, they tripped up on the very last comment: “the red color of the rocks and soil (at the Viking lander site, 1976) is probably due to highly oxidized iron-bearing minerals” (interpreted from a color enhanced image! I am sure Alex can confirm that?)

Alex writes:
I'm not sure what you driving at with the "tripped up" comment. The "red color of the rocks and soil..." on the Martian surface is generally (but not exclusively) attributed to "highly oxidized iron-bearing minerals." I don't have any particular problem with this statement.

Alex R. Blackwell
University of Hawaii