The Great Meridiani Debate

[paulanderson]

Acidic water or volcanoes / impacts? The debate is on! I kind of like this actually, for my birthday today (39 now, getting old)... <img src="/images/icons/wink.gif" /><br /><br />Updates regarding this today from Nature, CU and Space.com:<br /><br /><b>The Waters Ran Shallow</b><br />http://www.nature.com/nature/journal/v438/n7071/edsumm/e051222-10.html<br /><br /><b>Mars Region Probably Less Watery In Past Than Thought, Says Study</b><br />http://www.colorado.edu/news/releases/2005/470.html<br /><br /><b>New Studies Question Mars Water Assumptions</b><br />http://www.space.com/scienceastronomy/051221_mars_dry.html<br /><br />Regardless though of whether they are correct or not regarding the acidic sulphate deposits in these scenarios, the earlier clays are still another matter...!<br /><br />The Space.com article includes comments from Squyres (who it says was not contacted prior to the article being published):<br /><br />"Squyres said a deeper understanding of the situation came when Opportunity examined Endurance Crater, where observations were made of 25 vertical feet of rock outcrops. Those results were published just a month ago, after the two Nature papers had been submitted. Knauth, McCollom and Hynek "hadn't seen that stuff when they wrote their papers," Squyres said. The nature of the layering and grain sizes deeper inside Endurance Crater "is absolutely incompatible with a volcanic or impact origin," Squyres said. It is "completely compatible" with the idea of windblown material, and the upper meter or so "shows evidence for deposition of water. The chemistry varies with depth in a way that requires that subsurface liquid water interacted with the rocks after they were deposited." Squyres emphasized that his

 

[bonzelite]

it seems that the general picture of late is that mars may indeed have a hydration cycle, but is subterrainean. and may have been that way for most of it's lifetime:<br />http://www.newscientist.com/article.ns?id=dn7709<br /><font color="yellow">Meteorites reveal extended deep-freeze on Mars<br />19:00 21 July 2005<br />NewScientist.com news service<br /><br />06 July 2005<br />Mars has never been much warmer than it is now, reveals the first detailed analysis of the planet's long-term thermal history – the current temperature on the equator is a bitter -58°C on average. The study suggests liquid water could not have survived for long periods on the Red Planet's surface, lowering the chances that life could have taken hold on the frigid world.<br /><br />Previous observations of channels and rocks altered by liquid water have pointed to periods when the surface temperature must have climbed above freezing. But this study adds to a growing body of evidence suggesting Mars has been piercingly cold during most of its 4.6-billion-year history.</font><br /><br />

 

[paulanderson]

I like Squyres' comments in today's <i>Rocky Mountain News</i>:<br /><br />"But the lead scientist on the Mars Exploration Rover (MER) mission dismissed the CU idea as misguided and uninformed. Cornell University's Steve Squyres said the Boulder scientists did not have access to reams of recent Opportunity data, all of which "really solidify the case that water was involved in a very substantial way at this place."<br /><br />http://www.rockymountainnews.com/drmn/local/article/0,1299,DRMN_15_4334345,00.html<br /><br />In the MER scenario, while the water was mostly underground in aquifers, it did come to the surface sometimes as temporary playas / salt lakes or ponds, which Squyres has outlined previously. And again, the types of clay deposits found by Mars Express and Spirit must not be ignored, as they required longer-lasting, less or non-acidic water to form, even if it was very early in Mars' history. Probably mostly in aquifers again, according to ESA, but I will take liquid water (non-acidic even better) wherever I can find it! <img src="/images/icons/smile.gif" /><br />

 

[paulanderson]

I received an interesting e-mail this morning from Tom McCollom at Colorado University, one of the authors of one of the new research papers in question. Quote:<br /><br />"First, we considered in our our article all of the chemical compositional data that have been published to date. The chemical compositions on which the more recent interpretations mentioned by Steve Squyres are based have not been published, and the MER team refused us access to these data when we requested. However, based on what we have seen in recent publications and information presented at conferences, there is nothing in these new data that would be inconsistent with our volcanic scenario, contrary to the claims that Squyres has made in the mass media. We intend to demonstrate this as soon as the data are made available to the broader scientific community."<br /><br />This will be a long debate...<br /><br />More articles also:<br /><br /><b>ASU geologists suggest Mars feature linked to meteorites, not evaporated lakes</b><br />http://www.asu.edu/news/stories/200512/20051222_mars_meteorites.htm<br /><br /><b>Mars Not so Wet After All?</b><br />http://www.nature.com/news/2005/051219/full/051219-10.html<br /><br />And a new phyllosilicates abstract:<br /><br /><b>Phyllosilicates on Mars and implications for early martian climate</b><br />http://www.nature.com/nature/journal/v438/n7068/abs/nature04274.html <br />

 

[JonClarke]

TRANSLATION: We have nailed our colours to the mast...<br /><br />I think the more recent results that squyres was refering to have been published in the recent Earth and Planetary Science Letters papers. Because of timing McCollom, Knauth and their associates would not have been able to take them into account before their papers were accpeted (there is a 4-8 month time lag between submission and publication for Nature.<br /><br /> <br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>