Sunday, August 19, 2007

Panspermia did life come from outer space? or is there no consensus in Science.

A vocal minority of biological investigators, including Nobel winner Francis Crick have put forward views stating that life as we know it ,did not commence here on Earth at all, but was imported from outerspace. Specifically that the ingredients and precursors such as spores or microorganisms from life bearing planets are transported across the Galaxy.

The first proponent of the Panspermia theory was chemist Svente Arrhinius .His view was the life bearing spores floated across space propelled by solar radiation.Francis Crick suggested it was transported on meteorites ,Fred Hoyle and Chandra Wickramasinghe suggested it was in the interstellar clouds that earth encounters on the grand precession that earth takes around the outer spiral of the Galaxy lasting some 150 million years.

The latter has some substance as the paleo records show “feast and famine’ in biodiversity and severe climatic oscillations ,due to changes in density in the interstellar medium.

The 2005 Deep Impact mission to Comet Tempel 1 discovered a mixture of organic and clay particles inside the comet. One theory for the origins of life proposes that clay particles acted as a catalyst, converting simple organic molecules into more complex structures. The 2004 Stardust Mission to Comet Wild 2 found a range of complex hydrocarbon molecules - potential building blocks for life.

Researchers at Cardiff University believe that recent probes inside comets show it is overwhelmingly likely that life began in space.

Professor Chandra Wickramasinghe and colleagues at the University’s Centre for Astrobiology have long argued the case for panspermia - the theory that life began inside comets and then spread to habitable planets across the galaxy. It is a controversial topic, but highly relevant for astrobiologists trying to understand the origin of life and potential for life on other planets.

The Cardiff team suggests that radioactive elements can keep water in liquid form in comet interiors for millions of years, making them potentially ideal “incubators” for early life. They also point out that the billions of comets in our solar system and across the galaxy contain far more clay than the early Earth did. The researchers calculate the odds of life starting on Earth rather than inside a comet at one trillion trillion (10 to the power of 24) to one against.

Professor Wickramasinghe said: “The findings of the comet missions, which surprised many, strengthen the argument for panspermia. We now have a mechanism for how it could have happened. All the necessary elements - clay, organic molecules and water - are there. The longer time scale and the greater mass of comets make it overwhelmingly more likely that life began in space than on earth.”

In an interesting counter argument researchers at Rutger have resurrected microorganisms from Antarctic ice.

The finding is significant, said Kay Bidle, assistant professor of marine and coastal sciences at Rutgers, because scientists didn’t know until now whether such ancient, frozen organisms and their DNA could be revived at all or for how long cells are viable after they’ve been frozen. Bidle is lead author of the article, “Fossil Genes and Microbes in the Oldest Ice on Earth.”

Bidle and his co-authors, Rutgers colleague Paul Falkowski, SangHoon Lee of Korea’s Polar Research Institute and David Marchant of Boston University – melted five samples of ice ranging in age from 100,000 to 8 million years old to find the microorganisms trapped inside.

…The researchers chose Antarctic glaciers for their research because the polar regions are subject to more cosmic radiation than the rest of the planet and contain the oldest ice on the planet.

“It’s the cosmic radiation that’s blasting the DNA into pieces over geologic time, and most of the organisms can’t repair that damage.”

Because the DNA had deteriorated so much in the old ice, the researchers also concluded that life on Earth, however it arose, did not ride in on a comet or other debris from outside the solar system. “…(T)he preservation of microbes and their genes in icy comets may have allowed transfer of genetic material among planets,” they wrote. “However, given the extremely high cosmic radiation flux in space, our results suggest it is highly unlikely that life on Earth could have been seeded by genetic material external to this solar system.”

Not quite a formative argument as we find that UV is the primary inhibitor in outer space and not CR.

The organisms that are exposed outside the space station are in a dormant state, so they cannot evolve. They are just surviving. We have found that solar ultraviolet radiation is the most damaging perimeter -- it kills all organisms so far known. Except that Rosa de la Torre from Spain recently exposed lichens, and discovered that they had the same biological activity as before they were exposed to the full sunlight. So that is something new. But we did find that if we shielded microorganisms against solar UV radiation with dust, even a dust sphere of just one centimeter, they survive pretty well in space. So that means little meteorites just one centimeter in diameter could travel for at least two weeks in space and the organisms inside would survive. I also participated in the NASA LDEF mission, the Long Duration Exposure Facility. Their microorganisms stayed in space for six years, and they also survived pretty well when they were shaded against UV radiation.

Indeed, as we observe from this paper.

GosNIIGenetika, Moscow, Russia
Comparative Analysis of Life Activity of Microoganisms Exposed to Short-Term Spaceflights
Voeikova, Tatiana A.; Tabakov, Viacheslav Yu.; Voeikova, Tatiana A.; Journal of Gravitational Physiology, Volume 13, No. 1;
July 2006, pp. P-209 - P-212;

In 1996-2005, streptomycetes, bacilli and enterobacteria were flown on Mir and Foton-M2 to study spaceflight effects on microorganisms. Streptomycetes developed changes in their morphogenesis and antibiotic activity, while bacilli remained essentially unchanged, and enterobacteria showed a higher survival rate than on Earth. The conjugative transfer of plasmids from enterobacteria to streptomycetes was accelerated. The 6-14 day exposure to the space environment did not increase mutation frequencies in streptomycetes or bacilli and did not cause plasmid DNA loss. However, streptomycetes carried on the outer wall of the Mir station showed significant genetic changes.

Researchers investigated peculiarities of microorganisms’ physiology and behavior in outer space already on board the “Mir” orbiting space station, and it became clear back at that time that bacteria changed significantly in extraterrestrial conditions. Experiments continued on board the “Foton М2” space vehicle intended for scientific research, back in 2005 the first batches of bacteria were launched on its board into outer space. Among them, there were several cultures of bacilli, streptomycetes and Escherichia coli. These microorganisms were selected not at random, they all differ from each other in physiology, biochemistry and genetics, thus providing a more comprehensive view on bacteria behavior in general.

In orbit, living organisms face not only lack of gravitation, but also cosmic radiation presence. Here is what happens to them. Bacteria in outer space become more aggressive, they simply begin to “eat up” spaceship components. This happens because microorganisms start producing enzymes unusual for them in terrestrial conditions. These enzymes destroy structural materials, which can result in both equipment damage and breakage. It is not improbable that bacteria become aggressive not only as regards to materials but also to human beings, so they can provoke unexpected diseases. In addition, cosmonauts experience immunodeficiency due to high load during the flight, which makes their organisms even more vulnerable.

Observations on board the “Mir” and “Foton М2” proved that microorganisms started to change even during short-term flights (12 to 14 days). For example, streptomycetes changed their appearance (size, shape and outline of the colonies’ surface). The in-depth analysis also revealed genetic modifications of microorganisms. The number of their mutations does not increase, despite the fact that this could be expected. However, some genes’ work is disrupted. Some genes that are “dormant” on the Earth, begin to work, it is them that generate the enzymes enabling microorganisms to eat up structural materials.

What does this tell us ,that consensus does not exist in science, that new research and innovative thought promote better scientific discourse and can overturn “conventional thinking” until the Theory can withstand the test of time.


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