Mars Phoenix provides further evidence that Viking may have missed organics on Mars.

[aphh]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>It's expected to be the "permanent" water ice layer.How old? I have no idea <br /> Posted by MeteorWayne</DIV></p><p>Thanks. Sure, it's permanent now, but 60 million years ago things might have been very different on Mars. The disintegration of advanced life might have worked a lot faster there than here on earth.</p><p>If advanced life, like rainforests, once existed on Mars, the evidence could be buried rather deep.&nbsp;</p>

 

[3488]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'><font color="#ff0000">Thanks. Sure, it's permanent now, but 60 million years ago things might have been very different on Mars. The disintegration of advanced life might have worked a lot faster there than here on earth.If advanced life, like rainforests, once existed on Mars, the evidence could be buried rather deep.&nbsp; <br /> Posted by aphh</font></DIV></p><p><font size="2"><strong><font color="#000000">Hi aphh,</font></strong></font></p><p><font size="2"><strong><font color="#000000">I do not think that Mars has changed much for the last several hundred million years, certainly not since the Cambrian Explosion of life on Earth. Perhaps Jon Clark or Bob Clark (exoscientist) know any different.<br /> </font></strong></font></p><p><font size="2"><strong><font color="#000000">If life did evolve on Mars, I doubt very much it got as far as rainforests. Probably amoeba, but not likely any further. The early collapse of the magnetosphere was a death knell, as the solar wind eroded Mars's atmosphere. True the volcanoes would have off set this for a while, but when their activity waned, the replenishment of the martian atmosphere was no longer possible.</font></strong></font></p><p><font size="2"><strong><font color="#000000">Wirh Mars's small size & lack of magnetosphere, the loss of its atmosphere was inevitable, leaving behind only the thin one we have today at Mars. In time, this too could go, leaving Mars more like the Moon or Mercury.</font></strong></font></p><p><font size="2"><strong><font color="#000000">Unless volcanism restarts & rejuvenates the martian atmosphere. </font></strong></font></p><p><font size="2"><strong><font color="#000000">Venus too, I know lacks a megnetosphere, but with a much stronger gravity, 93% G & possibly active volcanoes, Venus currently has no problem keeping & maintaining its dense atmosphere.<br /></font></strong></font></p><p><font size="2"><strong><font color="#000000">Andrew Brown.</font></strong></font></p> <div class="Discussion_UserSignature"> <p><font color="#000080">"I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>

 

[JonClarke]

<p>If Phoenix comes up negative for organics andd people still want to look for organics then yes, we need to go deeper.&nbsp; Certainly metres, to get below the zone of impact gardening and the influence of other surface processes.</p><p>Drilling is one way, the walls of very&nbsp;fresh impact craters is another, even dropping impactors from orbit or space and loking at the hole.</p><p>For deeper sections you wouldn't go to Olympus Monds because it's all a volcanic edifice.&nbsp; But the Thanuasia region would be one the place, the only fold belt on Mars, or the walls of a large or very large eroded crater, or of a valley, or the Valles Marineris rift.&nbsp; in these places you will still need to be able to dig down several metres to get to frsh rock.&nbsp; But it would be easier than drilling several km, perhaps.</p><p>Note that drilling or excavating more than a few metres becomes very difficult for robotic missions, and would almost certainly require human presence.&nbsp; So would accessing a cliff or valley side section.</p><p>Jon</p> <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>