I am curious as to whether all this hand waving about CO2 flows may be more about exorcising the ghost of Percival Lowell rather than describing what actually is found on Mars. --- Michael Turner <[EMAIL PROTECTED]> wrote: > > DS Michaels writes: > ====== > Hoffman's general approach on CO2 flows is described > at > http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2002AGUFM.P51B0354H&; > db_key=AST&high=4061e3e63a18001>> > > This paper speaks of catastrophic outflows that can > produce sudden torrents > of supercritical CO2 that could, under just the > right circumstances, produce > the braided and cut channels we see on Mars. I seen > nothing whatsoever that > suggests pools of liquid CO2 could have existed long > enough to produced > layer bedrock, salt deposits et al. > ====== > > Hoffman's general approach doesn't include all his > specific thinking on > White Mars. I distinctly recall seeing Hoffman > sketch a scenario of a > high-density (if short-lived) CO2 atmosphere with > pressures strong enough to > keep liquid CO2 bodies on the surface in liquid > phase. Annoyingly, at the > moment, his site is down, and I can't find the > keywords for a Googlecache > version. I can't speak to the issues of layer > bedrock or salt deposits. > Layer bedrock doesn't seem implausible with a liquid > CO2 surface > environment, if it lasts long enough. Salt > deposits? My geochemistry is > vestigial at best. > > Hoffman's main argument rests on the lack of surface > carbonates, and I > haven't followed the news from Mars closely enough > to know whether that > picture has changed. > > BTW, Hoffman has never said that life is so terribly > unlikely even in a > White Mars scenario, since subsurface environments > might be hospitable > enough. > > Nor do I see White Mars in itself being exclusive of > Warm Wet Mars periods. > The occasional collision might have released a lot > of CO2 and particulates, > warming Mars for relatively short, but formative, > periods of time, keeping > H2O in the atmosphere and/or precipitating long > enough to make a difference. > We may be looking at a planetary surface in which > CO2 gas flows AND CO2 > liquid flows AND H2O liquid flows have all played > roles at different times. > After all, it wasn't so long ago that glaciers were > finally recognized as > having significantly changed parts of the earth's > surface. I can't remember > anyone talking about glacial activity on Mars at > some point, but why not? > It takes all kinds (of phases and substances) to > make a world. And whatever > Mars is, it's a world - not just a spherical rock > with some frosting on the > top and bottom. > > Hoffman is a petro guy, he comes late to astronomy > and planetary studies. > It's perhaps tempting to take potshots at mainstream > theory in another > field, while safely ensconced in your own. On the > other hand, Alvarez & Son > came from halfway outside the field of evolution and > extinction (Luis > definitely from outside), but now the idea that a > big collision killed the > dinosaurs has become the accepted wisdom (even if > more recently under attack > again.) > > Sometimes the voices from outside are right, or at > least helpful in breaking > up theoretical logjams. > > -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/ >
===== Sincerely James McEnanly __________________________________ Do you Yahoo!? Yahoo! Finance Tax Center - File online. File on time. http://taxes.yahoo.com/filing.html == You are subscribed to the Europa Icepick mailing list: [EMAIL PROTECTED] Project information and list (un)subscribe info: http://klx.com/europa/
