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Mars Rovers Find More Evidence of Water
loconet writes "Space.com and JPL are reporting that the Mars Rovers might be on the verge of confirming that large amounts of water once flowed in a region of Mars that has looked curiously dry until now. Such a finding could be comparable to their discovery earlier this year of an ancient shallow sea on the other side of the red planet. Opportunity has found lumpy, odd rock unlike anything its seen to date. The rock concentration seems much rougher than the 'blueberries' found earlier on in the mission. Researchers hope to swing by the rock on the way out of Endurance for further study. 'It could just be one big mass of concretions,' Squyres said. 'I just don't know.' Meanwhile, Spirit, which has now climbed about 10 yards up a hillside, getting above the Gusev plain, found an interesting rock dubbed 'Longhorn'. Both rovers have been exploring more than twice as long as they were designed to last. And even though the Martian winter is at its coldest, engineers are confident that the rovers will continue, despite showing signs of mortality."
more evidence from a diff perspective. It seems pretty likely now that water *did* or perhaps is even still, on Mars. cool.
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I think that the leading theory is that the water is locked up beneath the surface as permafrost.
Isn't it possible, since Mars does not have a thick atmosphere like earth, that rocks that are found on Mars's surface are not nessicarly from mars?
Anything that fell from orbit would still end up partly melted, probably fragmented, and showing signs of shock and heating from impact in its mineral structure. This is partly how we identify things like the antarctic Mars rocks as being from Mars.
By contrast, conglomerates like the rock found now are weak and brittle, and wouldn't survive re-entry and impact intact. The other sedimentary minerals found have structures that would also have been changed by something as traumatic as falling from space.
So, minerals on Mars that look like they were formed in water, almost certainly had to have formed in water that was on Mars.
You could if there was no tilt to its axis of rotation relative to its orbital plane.
Mars, though, tilts about the same as Earth - 25 degrees or so. But its orbital eccentricity has a 19% variance, versus Earth's 2%. The 'Southern Winter' is much longer and colder than the 'Northern Winter,' and the whole planet is colder. The Martian Southern hemisphere experiences much greater temperature variance than any point on Earth.
Seasons on Mars
The Mars Odyssey mission found water within a meter of the surface in many places on Mars. Aeolian (wind) erosion processes are noticably different from water erosion processes (at least, that's what the geologists say - I won't pretend I can tell the difference myself just looking at something). Carbon dioxide freezes into a solid and then sublimes - liquid CO2 requires very high pressures, and the Martian atmosphere has a pressure some 1% of earth's. Other possible liquids such as methane require significantly colder temperatures to condense than what are available on Mars. Meterorite impact frequency isn't a function of atmospheric density - just they'll burn up less before hitting the ground, and then, yes, hit harder - but blast shockwaves aren't going to create the 'razorback' structures found in some of the cracks of the rocks at Endurance crater. Also, elements in the correct ratio to be particular salts are being found in the rocks, and some of these salts are known as ones that would be carried in water. We can draw similarities to the moon, but not many - again, aeolian processes will influence martian geology strongly, and there is no atmosphere or carbon dioxide ice or water ice on the moon (minus some possible craters, look up DoD/Clementine's recent moon imaging).