Phoenix science results, Beginning with December 2008 AGU meeting |
Phoenix science results, Beginning with December 2008 AGU meeting |
Dec 15 2008, 09:22 PM
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Administrator Group: Admin Posts: 5172 Joined: 4-August 05 From: Pasadena, CA, USA, Earth Member No.: 454 |
I figured it was time for a new thread, since we finally seem to be getting some science results out of Phoenix. The press release should be out shortly.
First numerical result I've heard was given by Peter Smith at today's press briefing at AGU: TEGA found that the soil is composed of 5% calcium carbonate, which is a significant result. Hopefully more will hit the Web soon -- post here when the links go up! --Emily -------------------- My website - My Patreon - @elakdawalla on Twitter - Please support unmannedspaceflight.com by donating here.
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Feb 21 2009, 01:54 PM
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Senior Member Group: Moderator Posts: 2785 Joined: 10-November 06 From: Pasadena, CA Member No.: 1345 |
Oh wait! I get it! Here's a possible mechanism for shrinkage of the remainder:
If the drop was cooling before it merged, then ice would have been crystallizing out of the solution! (refer to simplified phase diagram Fig 1 in abstract) The drop would thus be non-uniform, a mixture of solid precipitated ice and salts in solution. I'd assume that the ice crystals would nucleate and form at the surface imperfection of the lander strut. So at the time of merge, the salt solution would be pulled over to the big drop, but most of the ice crystals would stay behind with the remainder. So at the instant of the merge, the salt concentrations of the remainder and merged drops would be the same. But after warming, and melting of the upper remainder's ice crystals, the salt concentration would be too dilute! Thus water could evaporate off the upper remainder drop until the preferred equilibrium concentration was reached. The remainder drop would shrink! -Mike [Now if I understand this right, it should also be possible to imagine a scenario/conditions where salts would have been precipitating at the time of merge. This would cause a remaining drop to grow faster than expected.] -------------------- Some higher resolution images available at my photostream: http://www.flickr.com/photos/31678681@N07/
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Feb 23 2009, 05:13 AM
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Member Group: Members Posts: 204 Joined: 29-June 05 Member No.: 421 |
If this really is liquid water, it would be a tremendous discovery. It seems a pretty hard conclusion to draw from three* monochrome and fairly low resolution images, with theorizing alone to back up the interpretation. I would really like to see laboratory replication of all of the lines of evidence that it is suggested that we observe in these images. For starters, what should be a pretty easy experiment: prepare a candidate perchlorate brine solution and a controlled experiment box which can replicate the temperature and pressure of the martian pole. Spray the brine on a metal pipe and take photographs under various lighting conditions. Compare with the images from Phoenix. Can you make spherules which look the same? Show clearly how to distinguish between lighting changes and motion and growth/shrinkage of droplets. Try doing the same thing with frozen droplets. Is there something that distinguishes the liquid from the frozen droplets in a still photograph? For a more advanced test, try to demonstrate the effects claimed as "smoking gun" signs in Renno et. al.'s abstract: if temperature, pressure, and humidity are varied over a cycle consistent what was observed by Phoenix, droplet growth is suppressed on material left behind by a droplet that merges with a neighbor; droplets grow selectively where the pipe is splashed with perchlorate salts; and their sizes and growth is proportional to their volume.
I'm really excited about the possibility of liquid water on mars today, but extraordinary claims require extraordinary evidence. So far this looks more at the level of (highly educated) speculation than an airtight demonstration of fact. (*can any of the image guru's tell me if there really are only 3 images of that strut? Or are there more that just weren't selected for the comparison, because lighting conditions differ or something?) |
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