James McEnanly writes: > As I understand it, the recent findings by the rovers > indicate deposits of gypsum and salt, which dissolve > in water, but not in supercritical CO2
As I've said several times in this thread: I don't see how liquid CO2 in one pressure/temperature regimen is at odds with liquid water in another regimen. And I don't see much wrong with Hoffman's view that major collision events could have taken Mars through brief, but highly formative, periods in which temperature/pressure regimens varied wildly from an equilibrium much like the one we see today. The specific phenomena I'm thinking about are not at the scale of chemical reactions, but at the scale of visible features. Sedimentation and layers could have been from a persistent CO2 liquid body, but exposure of the strata from an H2O flash flood. Likewise, the sorts of surface ripples observed in soil that we associate with flows of liquid water might have been caused by liquid CO2 flows. We've all seen liquid water, all our lives. Streams, lakes, rivers, rain, oceans. I've never seen liquid CO2. I understand it has important industrial uses, and I believe it exists because it would take a massive and silly conspiracy to delude people about its existence, a conspiracy with no obvious point. Apparently, so does Eugene Leitl. But that's not the problem here, I suspect. In studies of what makes for an "intuitive" user interface design, exasperated scholars finally had to conclude: the intuitive is the familiar. Liquid CO2 is unfamiliar. Liquid H2O is ubiquitous. I'm typing this with fingers made substantially of liquid-phase H2O. The appropriate question in looking at a planet like Mars in this context is: so what? We should try to understand what Mars *really* is, not to try fit it into models of what we *hope* it is. Unlike a user interface, we can't design Mars. I recently ran across an interesting comment in researching a book I'm trying to write, a comment about Hipparchus of Rhodes. This comment happened to be from a military historian. This historian said that Hipparchus made an important, but sadly neglected, contribution to astronomy when he put forth the view that there wasn't enough data yet (despite centuries of Babylonians before him) to draw conclusions about the architecture of the solar system. The historian, Rob Rice, was of the opinion that rushing to judgment on this issue held astronomy back, for centurues, up to, and even through, the time of Galileo. Of course, given the highly theocratic strain of governments in those times, issues like how the solar system is put together will inevitably bring in political factors that complicate the efforts of scientists. But scientists themselves, ambitiously seeking a grand unified theory, an architecture from a God with a sense of esthetics, presumably a God in whose image we were made, played a role in the confusion as well. Hipparchus was perhaps unusually humble among scientists - he was willing to shrug and say "absence of data = no faith." And things are probably worse than Hipparchus imagined. To paraphrase what some wag said: the Universe is not only messier than we imagine, it's messier than we *can* imagine. I can't imagine a world where CO2 phase changes were as important, or perhaps more important, than H2O phase changes. But maybe I don't have to. Maybe I'll just have Mars, as it really is. But I don't want to wait 20 years to find out that those oceans were really *not* water after all, after a long program based on the impatient and optimistic assumption that they were. If there's a chance to nail this, now or soon, it should be taken. I know I'll accept the verdict either way, so long as the trial is conducted fairly. -michael turner [EMAIL PROTECTED] == You are subscribed to the Europa Icepick mailing list: [EMAIL PROTECTED] Project information and list (un)subscribe info: http://klx.com/europa/
