A question here, behaviour of water on Mars Options

[spdf]

A question here

There are signs that in the past there was liquid water on Mars. So lets assume thats true.
Since the gravity on Mars is much lower than on Earth, so how does water (waves) behave on Mars compared to Earth?
Someone did say, that waves would have been much higher but also much slower. Is this true? Does anyone have an animation where you can see a waive on Earth in comparsion to a wave on Mars?

Thanks

[nprev]

Mike or HDP Don, how different are the curves for sulfur salts from chlorides? (Hope that wasn't a faux pas; afraid I've forgotten most of my basic chemistry). Martian brines, if any, might be considerably different chemically then their terrestrial counterparts, and the crust is certainly sulfur-rich.

[dburt]

Mike or HDP Don, how different are the curves for sulfur salts from chlorides? (Hope that wasn't a faux pas; afraid I've forgotten most of my basic chemistry). Martian brines, if any, might be considerably different chemically then their terrestrial counterparts, and the crust is certainly sulfur-rich.

Very different, in that common sulfates (e.g., of Mg) can't depress freezing the point more than about 5 degrees C, whereas NaCl (sodium chloride table salt) depresses it about 20 C, MgCl2 about 34 C, and CaCl2 about 50 C. Chloride salt mixtures gain several extra degrees below that (so-called eutectic freezing). Therefore any low temperature brines on or in Mars would have to be dominated by chlorides, a group of salts that can't normally be detected by infrared spectroscopy (TES and THEMIS from orbit, and Mini-TES on the rovers). That is, Mars could be chloride rich, and the salts would be difficult to detect. In this regard, their greater solubility and greater tendency to be frost leached (via freezing point depression) suggests that chloride salts should be less persistent than sulfate salts at the martian surface.

Nevertheless, chloride-rich areas on Mars have recently been inferred by this very lack of an IR signal - they look something like a "black hole" to IR spectrometers. See, e.g., Fall AGU abstract P13D-1563 by M.M. Osterloo et al.
http://www.agu.org/cgi-bin/SFgate/SFgate?&...P13D-1563"
Several of these inferred chloride-rich areas were suggested as possible landing sites for the Mars Science Lander (MSL), but didn't make the semi-final cut a couple of weeks ago.

Gsnorgathon, with regard to cooking with salt, I stand corrected. I perhaps should have said, "among other reasons" or "one reason" and not "the reason". (Adding salt is commonly recommended even for the simplest of recipies such as boiling an egg, where the taste of the salt might be undetectable.)

Ngunn, with regard to Mike Hecht, you could start here:
http://www.lpi.usra.edu/meetings/lpsc2001/pdf/1364.pdf
although he also published longer papers later. Personally, I enjoyed the exciting description of metastable water in an active outflow channel in the novel "Red Mars".

-- HDP Don

[nprev]

Very different, in that common sulfates (e.g., of Mg) can't depress freezing the point more than about 5 degrees C, whereas NaCl (sodium chloride table salt) depresses it about 20 C, MgCl2 about 34 C, and CaCl2 about 50 C. Chloride salt mixtures gain several extra degrees below that (so-called eutectic freezing).

Thanks! That's really a dramatic difference. I presume those values are referenced to terrestrial standard temperature & pressure? Has anyone crunched the numbers for average Martian STP (if they've derived that in any meaningful form yet, that is)?

[dburt]

Thanks! That's really a dramatic difference. I presume those values are referenced to terrestrial standard temperature & pressure? Has anyone crunched the numbers for average Martian STP (if they've derived that in any meaningful form yet, that is)?

Inasmuch as brine, salt, and ice are all condensed (non-gaseous) phases, changes to pressure should have very little effect until the pressure gets so low that the brine boils or the ice sublimates (definitely a consideration for Mars - but less of a concern for chloride brines, owing to the tremendous lowering of the activity of H2O in such brines, as mentioned above). The salts might lose waters of hydration too, although this doesn't affect the basic argument about freezing point depression. A lot of basic data is given in a 1980 Icarus paper by Brass, "Stability of brines on Mars" that Knauth and I cited in our 2002 and 2003 papers.

And Juramike - thanks for the added insight on the safety of adding salt to water before boiling it - yet another reason to do so, and undoubtedly the most important one. I guess you can tell this professor doesn't cook much.

-- HDP Don