PDA

View Full Version : 4 indicators of biological origin



patrick
2004-Jun-12, 11:15 PM
This topic has been discussed earlier here, concerning potential signs of current biology on Mars today. I've been gathering various sources about it elsewhere too and thus came up this post hoping it will prove a valuable discussion on possible life on mars.

Case1: dune spots at the South Pole:
These are spots (not to be mistaken with spiders) that annually reappear at the same location, which indicates that new formations are somehow linked to the former. Spots form in the spring and by the time itís summer, the area is defrosted and the underlying soil appears leaving markings behind caused by these spots. Defrosting is a proccess independant from the soil, yet their appearance is fixed on the surface, indicating formation is triggered on the soil, under the icesheet. Biological origin can account for such phenomena.
http://www.flextennis.com/test/biology3.jpg
http://www.lpi.usra.edu/meetings/lpsc2002/pdf/1109.pdf

Case2: oxygen:
Deficiency of any volcanic activity, current detected readings can account for possible biological indicators:
-benzene
-ammonia
-formaldehyde
Currently oxygen (0.13%-0.14%) is detected in the Martian atmosphere, perhaps very well through photosynthesis.



Primary refs for CO2 photolysis to CO and O2 on Mars are:
E. S. Barker, 1972, Nature 238, 447-448
N. P. Carleton & W.A. Traub, 1972, Science 177, 988-992
J.T. Trauger & J. I. Lunine, 1983, Icarus 55, 272-281
All three of the above ref'ed in "The Planetary Scientist's Companion," K. Lodders & B. Fegley Jr., 1998, Oxford Univ. Press


Case3: vegetation image1
The appearance of what seems vegetation with shrubbery radiating out from a central core. Notable is the change of color gradation with the same uniform formation throughout the strip. On Earth deteriorating vegetation tends to undergo such color gradation identically.
http://www.flextennis.com/test/biology4.jpghttp://www.msss.com/moc_gallery/m07_m12/smallmaps/M08/M0804688.jpg




http://www.msss.com/moc_gallery/m07_m12/images/M08/M0804688.html


Case4: vegetation image2
This image was discussed earlier on this board. Green scrub covering the underlying surface features. Whatever the actual color may be (calibration settings), the depicted scub does not share the same soil color.
http://www.flextennis.com/test/biology1.jpg
http://esamultimedia.esa.int/images/marsexpress/032-060404-0097-6-co-02-VallesMarineris.jpg

Ian Goddard
2004-Jun-13, 03:40 AM
Majic recently posted some remarkable dune spots (http://www.badastronomy.com/phpBB/viewtopic.php?t=13641). The best explanation I've seen for a seasonal dune-spot like phenomenon known as fans that are associated with "spiders" (some are seen in the posted images above) is Hugh Kieffer's hypothesis, which is geogenic and corroborated by the following study by Piqueux, Byrne, and Richardson:

Journal of Geophysical Research E: Planets (108.8, 2003)

Sublimation of Mar's southern seasonal CO2 ice cap and the formation of spiders

In this paper we define and describe morphological features that have colloquially been termed "spiders" and map their distribution in the south polar region of Mars. We show that these features go through a distinct seasonal evolution, exhibiting dark plumes and associated fan-shaped deposits during the local defrosting of the seasonal cap. We have documented the seasonal evolution of the cryptic region and have found that spiders only occur within this terrain. These observations are consistent with a geyser-like model for spider formation. Association with the transparent (cryptic) portion of the seasonal cap is consistent with basal sublimation and the resulting venting of CO2 gas. Also consistent with such venting is the observation of dark fan-shaped deposits apparently emanating from spider centers. Spiders are additionally confined to the polar layered deposits presumably due to the poorly consolidated and easily eroded nature of their upper surface.

Full Martian-spider study: www.gps.caltech.edu/~shane/2002JE002007.pdf

patrick
2004-Jun-13, 09:22 AM
I am not sure if these spiders are the same as the spots mentioned, since spiders, according to the article, are (wind/gas)deposits with branching characteristics, while the spots represents naked dark soil of the dune itself, uncovered by defrosting only.

A hypothesis of the spots I refer to would be, as explained in the links provided below, photosynthetic surface organisms that absorb sunlight, warm up and result in melting ice around them, whereby their growth and reproduction become possible. The ice cover above the liquid water provides excellent heat and UV insulation, prevents fast evaporation, and sustains basic living conditions until the ice cover is gone. The same mechanisms can be found on Earth in ice covering lakes at the South Pole.

http://www.darkcalgary.com/~walter/ganti-oleb2002.pdf
http://www.martianspiders.com/oleb/OLEB_Mars%2003-09-24c.pdf

Ian Goddard
2004-Jun-13, 03:38 PM
I am not sure if these spiders are the same as the spots mentioned, since spiders, according to the article, are (wind/gas)deposits with branching characteristics, while the spots represents naked dark soil of the dune itself, uncovered by defrosting only.
Your "Case 3" above contains spiders (http://www.gps.caltech.edu/~shane/2002JE002007.pdf), which you describe as "radiating out from a central core." The actual "spiders" are residual branching formations etched into the surface below the variety of seasonal dark spots called fans that appear seasonally on seasonal CO2 ice sheets above spiders. It's possible that the dark material involved in fan formation is similar to that involved in other spot formations.

Eye-Zee
2004-Jun-13, 03:40 PM
Case2: oxygen:
Deficiency of any volcanic activity, current detected readings can account for possible biological indicators:
Currently oxygen (0.13%-0.14%) is detected in the Martian atmosphere, perhaps very well through photosynthesis.


Primary refs for CO2 photolysis to CO and O2 on Mars are:
E. S. Barker, 1972, Nature 238, 447-448
N. P. Carleton & W.A. Traub, 1972, Science 177, 988-992
J.T. Trauger & J. I. Lunine, 1983, Icarus 55, 272-281
All three of the above ref'ed in "The Planetary Scientist's Companion," K. Lodders & B. Fegley Jr., 1998, Oxford Univ. Press


Photolysis and photosynthesis are not related. There is no evidence on Mars to date of photosynthetic processes or pathways.

patrick
2004-Jun-13, 03:55 PM
The actual "spiders" are residual branching formations etched into the surface...

With regard to the plants, you say are spiders; I have to disagree if they are indeed etched into the surface, which wouldn't qualify them as spiders. Of course it remains speculation based on images but one would expect, if they were etched, to have simular color features with the soil.

Ian Goddard
2004-Jun-13, 04:43 PM
The actual "spiders" are residual branching formations etched into the surface...

With regards to the Plants; I have to disagree if they are indeed etched into the surface, which wouldn't qualify them as spiders. Of course it remains speculation based on images but one would expect, if they were etched, to have simular color features with the soil.
The appearance of spiders change over the seasons as ice forms and melts away (see (http://www.gps.caltech.edu/~shane/2002JE002007.pdf)). However, the underlying spider formations exposed during the period when overlying ice has melted away do not change. Majic posted (http://www.badastronomy.com/phpBB/viewtopic.php?t=11490) an inquiry into the question of whether the spider branches are concave (channels in the surface) or convex (like branches on the surface). The conclusion of that inquiry was that lighting based on actual sun position supports spider-branch concavity, which is consistent with the Kieffer hypothesis (http://www.gps.caltech.edu/~shane/2002JE002007.pdf).

patrick
2004-Jun-13, 06:36 PM
Photolysis and photosynthesis are not related.

Photolysis: the part of photosynthesis (the process by which carbon dioxide and water are converted into carbohydrates) that occurs in the granum of a chloroplast (structures found within the cells of plants) where light is absorbed by chlorophyll (the green pigment involved in photosynthesis itself), turned into chemical energy, and used to split apart the oxygen and hydrogen in water.

Eye-Zee
2004-Jun-13, 08:03 PM
Photolysis and photosynthesis are not related.

Photolysis: the part of photosynthesis (the process by which carbon dioxide and water are converted into carbohydrates) that occurs in the granum of a chloroplast (structures found within the cells of plants) where light is absorbed by chlorophyll (the green pigment involved in photosynthesis itself), turned into chemical energy, and used to split apart the oxygen and hydrogen in water.

Pardon me. More specifically, the photolysis in the references I cited is not related to photosynthesis. Photolysis as a chemical process by which molecules are broken down into smaller units through the absorption of light. The process take place in Mars' atmosphere. In the references with regard to Mars, photolysis has thing zero to do with life-based photosynthesis.

Grego
2004-Jun-15, 01:02 PM
Majic recently posted some remarkable dune spots (http://www.badastronomy.com/phpBB/viewtopic.php?t=13641). The best explanation I've seen for a seasonal dune-spot like phenomenon known as fans that are associated with "spiders" (some are seen in the posted images above) is Hugh Kieffer's hypothesis, which is geogenic and corroborated by the following study by Piqueux, Byrne, and Richardson:

Journal of Geophysical Research E: Planets (108.8, 2003)

Sublimation of Mar's southern seasonal CO2 ice cap and the formation of spiders

In this paper we define and describe morphological features that have colloquially been termed "spiders" and map their distribution in the south polar region of Mars. We show that these features go through a distinct seasonal evolution, exhibiting dark plumes and associated fan-shaped deposits during the local defrosting of the seasonal cap. We have documented the seasonal evolution of the cryptic region and have found that spiders only occur within this terrain. These observations are consistent with a geyser-like model for spider formation. Association with the transparent (cryptic) portion of the seasonal cap is consistent with basal sublimation and the resulting venting of CO2 gas. Also consistent with such venting is the observation of dark fan-shaped deposits apparently emanating from spider centers. Spiders are additionally confined to the polar layered deposits presumably due to the poorly consolidated and easily eroded nature of their upper surface.

Full Martian-spider study: www.gps.caltech.edu/~shane/2002JE002007.pdf

These ideas don't work really, they are the same as we published in our paper and well before these guys:

http://www.martianspiders.com/martianspiders.pdf