Phoenix science results, Beginning with December 2008 AGU meeting Options

[elakdawalla]

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

[fredk]

There's an article on New Scientist about this:

http://www.newscientist.com/article/dn16620

In that article there's a link to this conference abstract:

http://www.lpi.usra.edu/meetings/lpsc2009/pdf/1440.pdf

[HughFromAlice]

conference abstract:

Very interesting abstract. I'm hanging out to hear the full exposition at the conference. This is an important topic with wide implications. Well, they say they have a smoking gun, and let's hope it doesn't turn out to be the smoky sublimation from an ice pistol (sorry I couldn't resist!).

This is basically the story of the photos of two spheroids on the legs of Phoenix. From these photos it looks like a smaller spheroid could have merged with a larger one just below it. For a really good enhanced photo - by HortonHeardAWho - of Phoenix leg and spheroids go to http://www.flickr.com/photos/hortonheardaw...392520/sizes/o/

From my amateur level of understanding the key underpinning general points are that: -
a. The index of refraction of liquid water is larger than that of water ice. [Thus - in these photos - a darker spheroid is likely to be liquid.]
b. If the spheroids were made up of supersaturated aqueous solutions they would grow due to attracting atmospheric water vapour hygroscopically (deliquescence).
c. If they were made up of ice, they would sublimate and so would shrink. [Counter argument: Alternative explanation for growth - water vapour from ice below Phoenix could have sublimated and recondensed on ice spheroids on the relatively cold (in shadow) legs faster than the spheroids were sublimating].

However, the spheroids are highly like to be liquid as: -
1. The fact that shapes observed were spheroidal suggests the presence of the liquid phase. (They could have gone through a number of freeze/thaw cycles).
2. The small upper spheroid darkened between photos. This suggests it changed phase from ice to liquid.
3. The spheroids look as if they joined between photos with the upper spheroid reduced in size afterwards (actual joining not observed). Thus they moved. Therefore they were liquid. [Counter argument - changing light between photos only gives the illusion of movement.]
4. Growth is suppressed in the smaller upper spheroid left behind.......suggesting that when it moved most of its salts were carried with it. [Implication - as a less concentrated solution it froze. This runs against the counter argument in a. above which indicates it should have grown].

Any experts out there, please feel free to correct me!