This is in response to Gary's post at:
http://www.habitablezone.com/space/messages/12957.html

Gary wrote:
Levin's whole argument stands on the notion that there are no oxidants on the Martian surface. The presence of oxidants on the Martian surface were actually predicted before Viking in an Icarus paper written by James Lovelock and Lynn Margulis. Prior to Viking, Levin was regarded as a clever engineer and respectible scientist. His unwillingness to accept the possibility of oxidants on the Martian surface (despite the abundant supporting evidence) has reduced his stature to that of a common crank. He is pathetic to watch with his repeated attempts to publish his junk papers in respectable journals but always failing.

Alex writes:
While I agree that Levin et al. are probably tilting at windmills, and that some of the Levin supporters border on outright crankishness, perhaps the issue is a little more nuanced than it might appear, though I do agree with your characterization of Levin's "unwillingness to accept..." IMHO, however, Levin's arguments regarding oxidants (at least superoxides) at the Martian surface do have some merit, and furthermore, he does have a point: none have been *directly* detected by remote sensing or in situ; their presence is only *inferred*. In all likelihood, this view is too constraining and little self serving. Unlike the Levin crowd (e.g. DiGregorio, who resorted to ad homenims), I (and most of the Mars community) were impressed with the Yen et al. experimental results announced last year

Yen, A.S. et al., “Evidence That the Reactivity of the Martian Soil Is Due to Superoxide Ions,” Science 289, 1909-1912, 2000.

which had support from MGS TES mineralogical data. In other words, positive/affirmative evidence backed up with solid lab results and modelling. Nevertheless, direct detection of superoxides has not happened to date, after all that was the purpose of the U.S.-supplied Mars Oxidant Experiment (MOx) aboard the ill-fated Russian Mars96 mission. Indeed, there are some good arguments (many that Levin made in his SPIE abstract) that superoxides CANNOT exist in the surficial environment given what we currently know about their properties, though I tend to fall on the other side of the issue for plausibility reasons.

Alex R. Blackwell
University of Hawaii