Summary of Today's Topic

     As technology advanced throughout the 20th century, the prospect of life on other planets in our solar system dwindled.  By about 1924, every planet in our solar system except for Mars had been declared unfit for intelligent life.  As such, the search for extraterrestrials began to focus on the red planet.  After the fiasco of the previously thought canals of Mars, the probability of intelligent life existing on Mars began to drop as technology advanced.  New technology, leading up to the space age, began to slowly rule out the possibility of life on Mars, and then a series of probes dashed hopes further.  Finally, a series of missions landed vessels upon the planet and concluded that it was highly unlikely that there was any form of microscopic life on Mars, even though some of the results were slightly ambiguous.

     The debate was mostly straightforward and slowly developing until the beginning of the Space Age. From roughtly 1924-1957, information about the temperature, atmostphere, and vegitation on Mars was gathered using spectroscopy and telescopic observation. Spectroscopy indicated low air pressure, an absense of chlorophyll, an abundance of carbon dioxide in the atmosphere, and temperatures below freezing. Coblentz and Lampland were two of the first scientists to deal with temperature on Mars. The determined this by using the light that came off of Mars to see what the atmosphere was made up of. From this, they concluded that Mars had an overall temperature of -28 degrees C with a higher temperature for darker spots, reaching 10-20 degrees C. Later, Adams and St. John, using a 60 in reflector and prism spectroscopy, concluded that Mars's atmosphere had 6% water and 16% oxygen with low air pressure. Kupier discovered that the main element that made up Mar's atmosphere was carbon dioxide. Hope for life on Mars was bleak, but hardy vegitation still seemed possible, if less exciting.

     Starting in 1957, the United States competed with the Soviet Union to explore outer space, especially Mars. The United States hurried to design and launch missions to collect data from Mars. The first of these were the Mariner missions, in which unmanned probes flew by Mars and took pictures upon passing.  The most important of these Mariner missions was the Marinier 4 in 1964 which did a mars flyby and to a partial photography of the surface and showed craters.  Also the Marinier 9 mission was very important, it orbited Mars in 1971 and photographed the entire surface of Mars, forever changing its image.  Among what it found were the largest mountian/inactive volcano in the solar system otherwise known as "Olympus Mons", a vast canyon system that runs along the Martian equator, known as "Valles Marineris", and other features that resembled the patterns of water-erosion we see on Earth.

      Eventually, the technology was well enough advanced that the United States was able to actually land an unmanned vessel upon the surface of Mars, and equip it with the materials to conduct experiments in the hopes of discovering life within the martian soil.  These missions were named Viking, and there were two Viking landers, each roughly opposite the planet from the other, which landed in 1976. There was a debate on whether or not to add a camera to the Viking landers in order to take pictures of the surface of Mars, from the surface. The people wanting a camera won out and the first photos taken directly from the surface were taken and viewed. They also placed this camera on the Viking on the off chance that if the planet was indeed inhabited, they might catch a glimpse of a lifeform walking by. The first pictures of Mars showed a desolate and rocky plain, void of obvious signs of life. Upon landing, they conducted several experiments which were designed to determine whether or not it was possible for the martian soil to house life, or if there was already organic material within the soil. The Viking landers perform 4 bio-chemical experiements on the Martian soil:

     1) Soil pyrolysis, which tested for organic compounds in the soil by heating it to 500 degrees celcius. The substace was sent through a gas chromatograph which would detect traces of organic compounds. The results were negative stating that no organic compounds existed within the soil of Mars unless the organisims were killed by the radiation of the sun upon creation.

     2) Gas Exchange test, the most earth-like test, which added a nutriet solution to a soil sample to feed bacteria that might be present. If bacteria were present in the soil, it would give off CO2 as a waste product, which could be detected by the Viking lander. The results were that an immediate release of Carbondioxide and oxygen occurred. This reaction was a chemical process because it was too fast of a reaction to be a biological process. Therefore the outcome for an organic basis in the soil of Mars was negative.

     3)Labeled release experiment, which was designed to measure the radioactivity of the soil.  This test also was designed to "feed" any organisms that might exist. The results of this test were an immediate release again of radioactive gas.  The gas was CO2 with Carbon-14, which is radioactive. Due to biological processes being sensitive to temperature there was a possible result for a biological process; however it is thought most reasonably that the results were negative and showed a chemical process which was the oxidation of nutrients by the soil. 

     4) Pyrolytic release experiment, which was the most Mars-like experiment of the four. Soil was put in a chamber with a light source and Mars atmospheric conditions. The soil was heated in the hopes of detecting waste products. The results was positive for organic life in very small quantities that can't be detected by the Gas Exchange test; however the relationship between the testing of heat is possibly a chemical process. This leaves the results as rather ambigious. Of the nine repetitions of the experiment, seven showed between 100 and 1000 bacteria, barely enough to register the experiment as positive

      The overall result of the Viking landers' tests were somewhat ambiguous, but seemed to point to a lack of life on Mars.  However, scientists were able to come up with several reasons for why even negative results might still allow for the possiblity of life on Mars.  Life on Mars could be different from life on Earth; we might need to test a different spot in the southern hemisphere or to dig deeper into the soil to discover life; we might need different tests; maybe life hasn't developed yet on Mars or prehaps it developed long ago and is gone now.  A lack of life on Mars does not mean that there never was or never will be life.  Since we do not know Mars' history, the options and possibilities are limitless and we can only make speculations based on our knowledge of Earth and life on this planet.  Mars could have life that is made up of completely different materials and undetectable by our scientific tests and instruments. Also, we have never physically been to Mars our selves to make so we could make different decisions and look for different things with our own eyes. The aftermath of the expedition to Mars left the planet, for the time, void of life as was tested for, however with the new information about the red planet it formed its own identity with its own unique features and characteristics.

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Key Terms and Definitions

"Big Science": Large scientific projects requiring large amounts of manpower and money, typically only able to be funded by the federal government, which became increasingly common after the end of World War II.

Exobiology: It is defined as the study of life outside the sphere of the Earth. Over time, the focus expanded to patterns of life anywhere in the universe, and the term became included in the larger scientific realm known as Astrobiology.The general concept is not only used for other planetary systems, however, as the principles often are applied to earth to discover more of the origin of life here, how we can use the earth model to determine theories about other planets, and other fundamental questions about life.

Contamination: Either having human elements disrupt scientific studies about the other planets or having extraterrestrial elements damaging the ecosystem or function of earth. It is a big concern for space missions, as the scientist do not want false positives on the tests they run. Furthermore, they want to make sure that they come back without some form of bacteria or other potentially hazardous life form or chemical from outer space contaminating the Earth. 

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