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View Full Version : What was in those droplets on the shaded legs of the Mars Phoenix Mission?



borman
2013-Feb-07, 03:30 AM
They appeared to change position over time. Was it fuel? Something from the soil deposited during landing?

If biological, was the motion consistent with collective bacteria?

Here is a paper that may offer constraints on the possible collective motion of bacteria:

Collective motion and nonequilibrium cluster formation in colonies of gliding bacteria

http://arxiv.org/abs/1302.0311

R.A.F.
2013-Feb-07, 03:58 AM
They appeared to change position over time.

Please provide examples/images, so that we may also examine these "droplets".

borman
2013-Feb-07, 04:31 AM
http://www.jpl.nasa.gov/news/phoenix/images.php?fileID=15811

Solfe
2013-Feb-07, 04:38 AM
I think they were brine droplets. This link is to space.com, which is ok, but not as official as the jpl site.

http://www.space.com/6394-phoenix-mars-lander-liquid-water-scientists.html

R.A.F.
2013-Feb-07, 05:50 PM
They appeared to change position over time.

Cite, please...the link you posted says nothing about any movement.


If biological...

Why the instant "jump" to something not evidenced?

R.A.F.
2013-Feb-07, 06:03 PM
I think they were brine droplets. This link is to space.com, which is ok, but not as official as the jpl site.

http://www.space.com/6394-phoenix-mars-lander-liquid-water-scientists.html

Ok....this link mentions movement, but doesn't go into specifics.

Supposing there is movemet going toward the surface, wouldn't gravity account for that?

Solfe
2013-Feb-07, 06:54 PM
At the time I saw this (when it was on the news), I was never sure if they were looking at series of stills or an actual video. I wrote off the movement as images of different droplets each time. They made it sound like condensation on a glass.

borman
2013-Feb-11, 05:12 PM
Here are some of the extended abstracts from the 40th LPSC regarding Phoenix and some biological considerations:
THE HABITABILITY OF THE PHOENIX LANDING SITE: A COMPARATIVE ASSESSMENT
http://www.lpi.usra.edu/meetings/lpsc2009/pdf/2082.pdf
GEOLOGIC SETTING AND SURFACE PROPERTIES OF THE MARS PHOENIX LANDING SITE
http://www.lpi.usra.edu/meetings/lpsc2009/pdf/1067.pdf
MARS REGOLITH THERMAL AND ELECTRICAL PROPERTIES: INITIAL
RESULTS OF THE PHOENIX THERMAL AND ELECTRICAL CONDUCTIVITY
PROBE (TECP)
http://www.lpi.usra.edu/meetings/lpsc2009/pdf/1125.pdf
PHYSICAL AND THERMODYNAMICAL EVIDENCE FOR LIQUID WATER ON MARS?
http://www.lpi.usra.edu/meetings/lpsc2009/pdf/1440.pdf
Perchlorate in Martian soil: Evidence and implications.
http://www.lpi.usra.edu/meetings/lpsc2009/pdf/2420.pdf
This last is interesting in light of recent Curiosity findings of possible perchlorate.
The first questions are where and how perchlorate is sourced. Then what vector spreads it around Mars. Does the percentage of perchlorate found at different sites fall within an unusually narrow range compared to other compounds that would require a rather specific vector? Is there also an unusual range of size constraint or is there a mix of large and small crystals of pechlorate at the sites of detection?
Answers to these questions can suggest or rule out a biological vector for spreading perchlorate. A bacteria on Mars would be wise to utilize a deliquescent salt in its membrane to acquire as much water as it can in the arid environment if it can make an enzyme that strips the water from the perchlorate used as a transport molecule. When the bacteria perish, perchlorates of a specific size would be left behind as biomarkers much the way magnetosomes may have been left behind.

brentrey
2013-Feb-12, 02:48 PM
Mars is not the best choice.

brentrey
2013-Feb-12, 02:49 PM
It's changing, not that consistent.

borman
2013-Mar-10, 11:52 PM
Some talk videos
Selby Cull touches on the globules about 13 minutes in. During the Q&A it was mentioned bacteria can survive at 7 mbar.
https://connect.arc.nasa.gov/p4cbkn97lbv/?launcher=false&fcsContent=true&pbMode=normal
Alfred McEwen discusses Recurring Slope Linea (RSL) which may indicate possible water or water brine sources. Typically they are dark but thinner than Slope Streaks. The rarer bright RSL seem located on different slopes in their discovery images using time lapsed images.
https://connect.arc.nasa.gov/p27eg800f7b/?launcher=false&fcsContent=true&pbMode=normal
A possible curious connection between Slope Streaks on biology, other than the “desert varnish” hypothesis, comes with Schorghofer’s discovery of a correlation between H2O triple point and where slope streaks are found. Bacteria that want to survive on today’s Mars need to be where the water is best accessible. At triple point it is accessible in all three forms. Slope streaks normally start at points near outcrops.
The outcrop could offer some cover from direct solar radiation while allowing access to triple point water. A portion of the colony may risk direct radiation exposure during early morning or late afternoon water ingestion times and die. Any enzymes or oxidants released as darkness falls may catalyze reactions that form the slope streaks. Slope streaks would then cease their formation at daylight where photo-destruction of organic material as well as H2O2 quickly terminates the formation process.

Noclevername
2013-Mar-11, 04:34 PM
Mars is not the best choice.

Best for what purpose?

borman
2013-Mar-22, 10:36 PM
Ongoing Rock Coatings a possibility
Whether it is varnish or some other currently ongoing process is not yet known. Is what was happening on the Phoenix struts related to Curiosity’s need to do 5 zaps instead of 1 to get to a particular sample’s ground truth?
Los Alamos science sleuth on the trail of a Martian mystery
http://www.lanl.gov/newsroom/news-releases/2013/March/03.19-martian-mystery.php

borman
2014-Jul-05, 11:11 PM
Although this thread has not been posted to for some time, a new paper will be online next week that gives results from experiments trying to mimic Phoenix conditions.

The title will apparently be:
Experimental evidence for the formation of liquid saline water on Mars
A press release has come out in advance of the paper:
Martian Salts Must Touch Ice to Make Liquid Water, Study Shows
http://spaceref.com/mars/martian-salts-must-touch-ice-to-make-liquid-water-study-shows.html
There were two experiments of note. A deliquescent salt was presented over the temperature range of Phoenix at the highest humidity conditions allowed, but no significant deliquescence occurred. In a second experiment, millimeters thick layers of salt was spread over a layer of ice of 3 millimeter thickness and at -100F drops of water formed.

The first result is important because even with the landing blowing dust on the legs that included deliquescent salt, drops of water on the leg is not an expectation. This would imply that either ice crystals or liquid water from a heated landing were deposited with dust and salt on the legs.
The second experiment with respect to the struts and legs may need further refining to use even more thin layers to show the same results. Is there a limit to how thin the ice and dust can be and still produce drops under Martian polar conditions?
Here, then, is a fine point to reconcile. We were made aware of the sublimation of exposed water ice, rather than frozen CO2, when the Phoenix scooper exposed chunks of ice to both the atmosphere and the sun. If there were salts to preserve against sublimation, they did not function. It is highly serendipitous, if not miraculous that the only legs to show the drops were shielded from the sun by the craft. The expectation would be that all the legs would suffer some coating rather than just a selection that happened to be shielded from the sun.

How can the drops survive extreme temperatures of Martian night and day, including temperatures below -100F, and water or ice on the legs be preserved from sublimation as monitored by Phoenix in sunlight?
One possible hypothesis is that there is some other factor in the soil, whether an abiotic catalyst or biotic enzyme, that is rendered ineffective or destroyed by direct radiation that assists the salt in not only performing its melting but helps to preserve from sublimation. If all the legs and struts were coated by the landing, the extra factor was destroyed by radiation letting the exposed legs sublimate their water component while the shielded fraction was allowed to accomplish the drop phenomenology.