Tag Archives: prebiotic factories

Life on Mars; what are we searching for?

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I believe alien life is quite common in the universe, although intelligent life is less so. Some say it has yet to appear on planet Earth. Stephen Hawking

I can only imagine H.G. Wells bitter disappointment if he were to learn that Martians were little more than primitive microbes.  All that hype and scare-mongering for nothing. Because that, it seems, is all we are ever likely to find on Mars. They may be intelligent microbes, but microbes nonetheless.

Present conditions on Mars are not conducive to thriving populations of anything living – at least in any life form we are familiar with. Incident UV and other solar radiation, low atmospheric pressure, an atmosphere almost devoid of oxygen, and the presence in soils of oxidizing molecular compounds such as perchlorates and hydrogen peroxide (think bleached hair), all contribute to rather inclement living conditions. It is possible that some life forms have survived these ravages, in sheltered enclaves or buried beneath the scorched earth, but it is more likely that, if life did exist on Mars, we will find the evidence written into ancient sedimentary rocks, or perhaps as chemical signatures.  It is these attributes that current exploration programs, both landed rover expeditions and orbiting satellites, tend to focus on. Continue reading

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The Ancient Earth 6. Life and all that… Part 2

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The Origin of Life? – Science persists in asking…

Not your ordinary enquiry - Galileo before the Inquisition

Galileo Before the Holy Office  Joseph Nicolas Robert-Fleury

When our Renaissance heroes Galileo, Copernicus, and Tycho Brahe cogitated the celestial sphere and removed humanity from the centre of the physical universe, they must have developed cricks in their necks – regularly looking over their shoulders for the ever-watchful ecclesiastical authorities who brutally insisted on maintaining the status quo.  Six hundred years later we still want to understand the unknown and persist in our curiosity, although the consequences of our enquiry are not usually as dire as those faced by Copernicus.  We continue to ask questions and one of these, for which there are still few answers, is ‘how did life begin?’.  Embedded in a question like this are metaphysical quandaries that consider consciousness and our humanity; one wonders whether such attributes will ever enter the realm of the empirical.  However, science can attempt to deal with explicitly empirical parts of the question, such as ‘how might organic molecules, that are critical to functioning cells, have formed on the ancient earth?’.

The first article on this thorny topic dealt with an iconic set of chemical experiments conducted in the early 1950s. This post takes these experiments incrementally further.

 

The molecularstructure of amino acidsIn 1953 Stanley Miller, then a young postgraduate student under the tutelage of Harold Urey, conducted experiments that produced several organic compounds, including amino acids. The chemical reactions were all abiotic. They demonstrated that some of the important chemical ingredients of living cells could be produced without the interaction of life-forms. This was a huge step forward in scientists’ understanding of how life arose on earth.

However…

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