Martian Water Suitable For Life

Nasa's Opportunity rover finds Martian water appropriate for the origin of life | Science | guardian.co.uk

Solander Point, Mars.

Photograph: NASA/JPL-Caltech/Cornell Univ./Arizona State Univ.

This article in today's Observer Across The Universe blog, by author Stuart Clark, caught my eye, especially in view of my recent blog about water on Mars, and what this means for the absurd 'Goldilocks Zone' argument used by Creationists.



NASA's now ancient Mars Exploration Rover, Opportunity, has recently found evidence that not only was there water on Mars but that that water was neutral. What this means for the uninitiated is that the water had an acidity the same as drinking water and very close to the acidity of most of the water in which life is now found on Earth.



Ignore the next three paragraphs if you know what pH is and why it is important to biochemical systems.

pH of some familiar substances

Very briefly, scientists measure acidity on a pH scale (probably from the German, potenz Hydrogen or power of hydrogen). The acidity of a solution is the amount of 'free' hydrogen ions (H⁺) it contains measured on a logarithmic scale based on the reciprocal of the amount of (H⁺), which means that for every decrease of 1 on the pH scale the amount of H⁺ it contains increases ten fold. The scale ranges from 1 to 14 with the lower the number the more acid is the solution. On this scale, a pH of 7 is neutral. Above 7, a mixture becomes increasingly alkaline as the amount of free negative ions such as OH^- increase relative to the amount of H⁺.



This is important to life because H⁺ is so reactive. Being H⁺ means that, in theory, it is simply a free proton, in other words a hydrogen atom (one positively charged proton and one negatively charged electron) which has lost its electron. Generally speaking, the smaller an ion is, and the more charge it carries relative to its size, the more reactive it is. Compared to other ions, H⁺ is incredibly small so is highly reactive. In practice it doesn't exist as such as it attached electrostatically to anything even hinting as a negative charge. Even in water, H⁺ attaches itself to H₂O molecules to form H₃O⁺ ions which then join together as long chains... but that's another story.



All biochemical processes need a fairly tight range of pH (usually slightly above 7) in order to work effectively and cells contain 'buffer' substances that mop up free H⁺ when they increase and release them again when the concentration falls, so keeping the cell's chemistry within the required range. Protein enzymes need a very precise shape to work and this shape is maintained by a dynamic interaction between the small variations in electrostatic charge over their surface, itself caused by interactions between negatively charged electrons and the positively charged atomic nuclei. H⁺, by attaching to them in its eagerness to find anything remotely electrically negative, can change this shape. In very high concentrations of H⁺, proteins and other biochemicals can be destroyed completely - which is why you don't stick your fingers in sulphuric acid.



What Opportunity has found are clay particles called montmorillonite which are formed under the influence of neutral water. This is believed to date from a time early in Mars's life when the climate was much more like that of earth and it rained frequently. Later on, as desertification progressed on Mars, the minerals dissolved in the water would have become more concentrated and the pH would have become more like sulphuric acid. For a time at least Mars had an environment in which self-replicating molecules could have arisen, so initiating the process that scientists believe led eventually to life on Earth.



So much for the Creationist notion that God an 'Intelligent Designer' created a special planet and put it carefully in a 'Goldilocks Zone' around the Sun so that it could create just the right 'fine-tuned' conditions for humans to live in and worship it by giving evangelical fundamentalist Christian pastors money and unaccountable political power. If there was ever a Goldilocks Zone its finely tuned narrow distance from the Sun must have included Mars as well.



One wonders also why an omnipotent designer would need a fine-tuned environment in the first place unless it isn't omnipotent and is as constrained by the laws of physics (and chemistry) as we are, in which case, ID advocates have a great deal of work to do to explain how this designer got designed and why it is subject to these higher laws.



I expect the Discovery Institute has professional liars swivel-eyed loons people working on that right now...



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