Lichen Survives In Space.
"Leopoldo Sancho from the Complutense University of Madrid, indicate that lichens have the capacity to resist full exposure to the harsh space conditions, especially high levels of UV radiation. Analysis post flight showed a full rate of survival and an unchanged ability for photosynthesis."
http://www.physorg.com/news8054.html

The algae in lichen rely on photosynthesis as plants do, therefore metabolize CO2. Therefore they might be able to survive as well on Mars. However, some photosynthetic organisms require oxygen as well. It's unclear if the species tested could survive in a largely CO2 atmosphere, though Mars does contain small amounts of oxygen in its atmosphere.

Gil Levin argued that some patches on rocks at the Viking landing sites gave the appearance of lichen:

Color and Feature Changes at
Mars Viking Lander Site.
J. Theor. Biol. (1978) 75, 381-390
http://mars.spherix.com/color/color.htm


Bob Clark

We've recently had a fairly extensive discussion of Levin's paper and other information on another thread here. In summary, though he was one of the very first people to try to work with Viking Lander color data, his analysis was half-competetent by somebody who barely understood what he was doing and it's results have been used in support of inferences that they do not substantially support. The paper also was "shopped around" to several peer-reviewed journals and finally published in a minor journal who's reviewers probably didn't have a clue what they were reviewing.

That lichens could survive space conditions is very surprizing, everybody expected that their DNA would be destroyed by radiations. Otherwise lichens have the ability to be completely dried up and restart when they receive water. This perhaps explains they were able to sustain vacuum, but it is still surprising.

That The Vikings could bring some lichens alive on Mars is possible (Although they were sterilized, I think). That those lichens would not die on Mars is still possible, if they can bear vacuum. But that they could grow and reproduce seems completelly impossible: they need liquid water, that seldom or never exist on Mars (at best some minutes when the morning frost receives the sun) and also something hotter than 0°C (Positive temps can exist on Mars, but if so water is evaporated for long).

"Every revolutionary idea seems to evoke three stages of reaction. They may be summed up by the phrases: (1) It's completely impossible. (2) It's possible, but it's not worth doing. (3) I said it was a good idea all along."
Arthur C. Clarke


A. C. Clarke said this in regards to revolutionary inventions. It can equally well be said in regards to revolutionary scientific discoveries.


- Bob

Simulations Show Liquid Water Could Exist on Mars.
"University of Arkansas researchers have become the first scientists to show that liquid water could exist for considerable times on the surface of Mars."
...
"There's a huge decrease in the evaporation rate the colder it gets, more than anyone realized," Chittenden said. With the dissolved sodium and calcium in the water, the freezing point for the brine mixtures drops to 21 degrees below zero Celsius for salt water and 50 degrees below zero for water containing calcium chloride."
...
"Brine formation could considerably increase the stability of water on Mars by both extending the temperature range over which liquid water is stable to negative-40 degrees Celsius and by decreasing the evaporation rates by two orders of magnitude," the researchers wrote."
http://www.physorg.com/printnews.php?newsid=7981



It may prove fruitful to make a comparison between the spectra of the moist Mars simulant in this experiment and the "mud-like" material seen with the "Magic carpet" at the Gusev landing site.



- Bob

Stating that things are impossible, and then changing into saying it is possible, is not is not a matter of the psychology of the stater, it is a matter that, usually, something new was discovered...


(Although often in History guies who said "it is impossible" were just dogmatic; "it is possible" usually went when the dogmatics died).

... like here, an example of (possibly) some new discovery which makes that something which previously looked impossible now appears possible.

The main problem about liquid water on Mars is not temperature, it is evaporation. Mars atmosphere is a giant drier. Only a much reduced evaporation rate (100 times less) can allow water to exist for more than some minutes.


The possibility of concentrated chlorides brimes at -50°C would explain many little facts, such as crusts in sandy terrains. But it makes not life much more likely, alas.

I would add that simulating Mars soil and atmosphere in real conditions is a really good idea. This could settle many disputes especially about which quantity of liquid water we can really find.

And if what Oppy observed in Meridiani planum was not a former free water, but a thin layer of water which formed under an ice layer, at a time where the pole where in this place? This could explain many things, especially why the strata are crisscrossing each other. (The overal flat appearance of this place would result of its particuliar erosion mode, which attacks prominent places while lower ones are protected by a layer of sand).

Crater Critters: Where Mars Microbes Might Lurk

http://www.space.com/scienceastronomy/0512...ce_tuesday.html

The more scientists have learned about Mars in recent years, the more some
believe that finding life might involve a deep drilling project.


* The Solar System Gets Crazier

http://www.space.com/scienceastronomy/0512...ery_monday.html

A swath of space beyond Neptune is getting stranger all the time as astronomers
find an ever-more diverse array of objects in various orbits and groupings.