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(Previous Page) Part 2: The 19th Century              



      By the end of the nineteenth century, there was a consensus in the scientific community that Mars was the only realistic possibility for extraterrestrial life the our solar system because it has some similarities to that of Earth. As a result, Mars was studied with greater enthusiasm. The search for life on Mars has persisted through the twentieth century and into the twenty-first. However, as better technology has allowed us to observe Mars more accurately, the possibility for life has only diminished. Yet paradoxically, new technology and information has also kept the debate alive by opening new possibilities for life on Mars. 


     In the late nineteenth and early twentieth centuries, there were two types of telescopes used: reflectors and refractors. Wider lens aperatures were ideal since they caught more light, allowing astronomers to see Mars more clearly. Astronomers in the nineteenth century also learn that the best and clearest observations of Mars are possible  when Mars is in opposition with Earth, about once every two years. With Mars in opposition and using some of the best telescopes of the day, Giovanni Schiaparelli and Percival Lowell both reported seeing patterns of intersecting lines on the surface of Mars.


     Schiaparelli was the first to observe the strange markings and called them "canali" in his paper. In his opinion, canali were likely natural geographic formations, like the English Channel and the Channel of Mozambique on Earth.[1] He did not explicitly reject the idea that they could be artificial, but he did not advocate that theory either. However, when Schiaparelli's paper was translated, a problem emerged: the Italian word canali can be translated into English as either "channels" or "canals." Both of these words have very different meanings: channels are thought to be natural while canals indicate artificial creation.


     In his book, entitled Mars, Lowell supported Schiaparelli's observations regarding canals on the surface of Mars.  He, himself, reported observing 183 canals with vegetation running along their sides, Martian "oases" at the intersections of the canals, snowy polar caps, and "unmistakable signs" of the planet being old, including the continents being all smoothed down and the oceans all dried up [2].  He applied the evidence that he was able to observe to the larger question as to whether or not the planet could sustain life, following Whewell's assertion that observable facts are necessary to support a belief.  Lowell found that "the broad physical conditions of the planet are not antagonistic to some form of life" and that a network of markings appear to be a system of irrigation that could provide water to the intelligent beings who built it.  Lowell's idea of intelligent beings on Mars became very popular, and sparked the imaginations of many, including H.G. Wells, who wrote the classic book The War of the Worlds about Martians coming to destroy Earth with superior weapons and space crafts. The idea of intelligent life on Mars, whether friendly or malicious, influenced the development of the space program throughout the twentieth century.


     The debate over whether the canals were natural, artificially made or simply illusions continued for two decades before it was finally settled.  Other astronomers such as Maunder and Antoniadi theorized that these canals were merely an illusion caused by disconnected patches, but they lacked sufficient evidence to go against Lowell & Schiaparelli. This theory of canals was prominent up until the time of the “Space Age”, when technology such as spectroscopy allowed the study of Mars to expand from the geography of the planet to its physical and chemical composition. Scientists learned that Mars has low air pressure, lacked chlorophyll, and contained high levels of carbon dioxide levels in its atmosphere making it only be able support hardy, moss-like vegetation and small burrowing animals at most. In the 1920s new technologies told scientists that Mars was very cold, only occasionally rising above 0 degrees Celsius.  Under these circumstances, complex or intelligent life as Lowell had suggested was certainly not realistic, and the prospects of the canals and life on Mars looked much bleaker.


     During the Space Age, the exploration of our solar system and the search for extraterrestrial life continued to garner significance in both political and scientific circles. Although the prospects for life on Mars had dwindled dramatically, for the first time governments were participating in the search by contributing incredibly large sums of money called "big science". Multiple programs were started with three goals in mind: to discover if life had ever existed on Mars, examine the climate and geology, and prepare for human exploration. During the mid-1960's and the late 1970's, NASA launched its first series of space missions. The first of such missions were the Mariner probes, which were unmanned probes that flew near the red planet and took pictures of the surface. 


      Throughout the course of the nine Mariner missions, NASA was finally able to lay to rest all debate about the so-called "canals" of Mars. Mariner 9 photographed what appeared to be old river beds upon the Martian surface, keeping the debate alive. As a result of these missions, NASA began to work on a new project, the Viking Landers, in the late 1960's.  Programs such as these used many new experiments in order to test for life, including soil pyrolysis, gas exchange, labled release and pyrolytic release. The gas exchange experiment hasd two stages it went through when testing the soil, in which it showed that microogranisms were not present. The label release experiment also tested for microogranisms but did so to see if they were able to metabolize and their stability under heat. The pyrolytic release experiment was different than the others because it tried to measure organic matter from atmosphere gases, which came up with mixed results as to whether there were biological or non-biological organisims present. In the end, there was no evidence to prove life on Mars and the possiblity of any sort of complex or multicellular organism due to lack of any sort of biosphere. Even the most hopeful for life on Mars were forced to concede possibilities for all but microbial life.


     In the last quarter of the twentieth century, one certain discovery called into question the negative results of the Viking mission. A Martian meteorite, named Allen Hills 840001, was discovered containing fossilized bacteria in Antarctica. Newly produced and more sensitive equipment for testing for life renewed the possibility that Mars could have supported life at some point. The ability to examine Allen Hills 840001 on earth gave scientists much more flexibility and precision when testing for life versus having to send probes or landers to Mars. Scientists now had the ability to include the results of the intital missions and perform new and improved methods of testing. They found out when the martian meteorite fell to Earth and how old it was due to these better methods.These new testing methods strongly supported that the fossils were either polycyclic aromatic hydrocarbons, tubelike structures, or carbonate globules. While there were many arguments stating the the new discoveries proved the existence of life on Mars, there were equal amounts of arguments against these ideas to say life did not exist.


     The capability for an up-close examination of the surface of Mars would greatly increase our ability to test for life and better understand the results, but for the time Allen Hills 840001 was the closest scientists could get to physically examining the composition of the planet. The better scientists were able observe Mars, the smaller the prospect of life seemed to get, but the possibility that life might exist can still not be ruled out. After a century of searching and testing, the answer to the question of life on Mars has still not been answered. The question of finding life on Mars is a prime example of science at its limits. No matter how much scientists can rule out extraterrestrial life, there will always be the possibility that they failed to see something, find something, or test something properly. Absence of proof is not proof against and even if we do find something the search will still continue for bigger and better options.


     The search for extraterrestrial life on Mars is a great example of a question that is verifiable, but not falsifiable. This aspect of falsifiabilty brings into question how accurate scientists are in applying the definitions of natural law, chemistry, and physics to the search for extraterrestrial life. The problem of  "demarcation of science" (distinguishing between sciences and pseudo-sciences or non-sciences) is an important one, even if it only effects the realms of public funding and social acceptance. An article by Karl Popper addressed this issue in the general scientific sense, calling into question whether or not the search for extraterrestrial life can even be considered a science. This idea says that in order for something to be considered a science it must be falsifiable, or there must be a test that can falsify it.

      To put this into perspective Popper used Marx's theory of history and Freud's psycho-analysis to show those cannot be scientifically classified because under any circumstance the results could be re-interpreted to support the theories. Furthermore, to better undertsand, one could consider the Christian religion, which is generally accepted to be non-scientific. Hypothetically speaking, should the Christian God tangibly appear to humanity and proclaim His presence, His existence would be verified.  On the other hand, there is no test to be done that can prove He does not exist; therefore, His existence can never be falsified.  Comparatively, the search for extraterrestrial life and intelligence, in relation to Popper's argument, is not science because we can only search for confirmations of life, and inherently cannot find evidence to disprove plurality, or falsify it. We have no way of empirically testing the supernatural and the testing for extraterrestrial life might be the same in a sense.


(Next Page) Part 4: The Origin Of Life

[1] Steven J. Dick, Life on Other Worlds: The 20th Century Extraterrestrial Life Debate (New York: Cambridge University Press, 1998): 30.

[2] Percival Lowell, Mars, p. 485 in Michael J. Crowe, ed., The Extraterrestrial Life Debate, Antiquity to 1915: a Sourcebook, 2008, pps. 485-492.




More canal information can be found here: The rise and fall of the canals on Mars

Comments (3)

Peter Ramberg said

at 10:27 am on Dec 6, 2008

This is a pretty good summary. It doesn't need much more material, but a bit more analysis. The falsification example is a good start. One way of providing this analysis is to use the framework of the "limits of science" of "frontier science" that we used in class. In all of these examples, the outcome of the debate was not yet known. This is characteristic of all research science, where scientists in the lab or field haven't yet agreed on what the "correct" answer is.

At any rate, streamline this text and add a bit more analysis using the framework we set up in class.

Peter Ramberg said

at 10:27 am on Dec 6, 2008

Also, add links to the previous and next sections of the essay.

Tim Weaks said

at 4:19 pm on Dec 7, 2008

I could not figure out how to link the footnote to the reference in the paragraph about Lowell that I improved upon. If someone who knows could fix it, that would be great! Thanks.

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