In 2003 Shane Byrne and I published a paper (Science 299, 1051-1053) using images from the camera on MGS and infrared data from Mars Odyssey to argue that the south polar cap has a thin covering (10 meters or 32.81 feet thick) of carbon dioxide ice but the remainder (3 kilometers or 1.86 miles thick) is water ice, as in the north.
My former graduate student, David Paige, was the Principal Investigator of this spacecraft. It was his baby, and I felt like its grandparent. We were both sad when the spacecraft was lost.
I had the same roles with Mars Global Surveyor (MGS) as I had with Mars Observer, but this spacecraft was an enormous success. In 2002 Huiqun Wang and I published a paper (Journal of Geophysical Research 107, No. E10) that used MGS data to measure dust and ice clouds on Mars.
I was an Interdisciplinary Scientist and a member of the Mars Observer Camera team. The loss of this spacecraft was the saddest day of my professional career.
In 1985 David Paige and I wrote a paper (Science 228, 1160-1168) that showed, using Viking data, how the north and south ice caps behaved differently when exposed to sunlight, consistent with water ice in the north and carbon dioxide ice in the south. We speculated about the cause of the difference.
In 1974 I wrote a paper (Journal of Geophysical Research 79, 3403-3410) summarizing the evidence that the permanent polar caps of Mars are water ice rather than carbon dioxide. Viking showed I was half right; the north cap is water ice.
In 1970 I wrote a paper (Science 168, 972-973) on the difficulties of making liquid water on Mars. Observations 30 years later suggest that Mars has gotten around these difficulties.