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Is a Mars Sample
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Is a Mars Sample
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| "You have to remember two things: One is that the Viking Landers landed in what would be more or less desert areas of Mars in order to find a very safe place on which to land, and so that kind of reduced the probability of finding organic material on the planet should it be there. Secondly, the sensitivity of that GCMS we sent there over twenty years ago is far less than the sensitivity that we are talking about here that we are applying with our Earth-based techniques." |
—Wesley T. Huntress, Jr., Associate Administrator for Space Science at NASA Headquarters at the 7 August 1996 NASA Life on Mars Press Conference. |
| "I've been shot down for my thoughts concerning life on Mars by people who kept saying the truth is in the simple explanation. For a long time, it was easier to explain my results with chemistry, which argued against life. But now, it appears the chemical explanation may be too complicated, and that life may be the simplest answer." |
—Dr. Gilbert Levin, designer of the labeled release experiments carried on the Viking landers, Chemical Innovation, 2001, 31, 12-16. |
| "Perhaps Martian samples can be safely returned to Earth. But I would want to be very sure before considering a returned-sample mission." |
—Carl Sagan, Cosmos, p. 129. |
In 1976, the National Aeronautics and Space Administration (NASA) landed Viking 1 and Viking 2 probes on the surface of the planet Mars with the express intent of searching for signs of life. While one of the "life detection" or microbiology experiments seemed to strongly suggest the presence of possible microbial life, a sensitive analytical device known as a gas chromatograph-mass spectrometer (GC-MS) failed to detect the presence of any organic material in Martian soil. This surprising result, especially in wake of evidence of organic material in lunar soils collected by the Apollo missions, suggested that organic molecules derived from meteoric material (which impact Mars continually) that should be present in the Martian soil were somehow being destroyed. A hypothesis was developed to explain the absence of these organic molecules by an "oxidation mechanism" that would decompose organic molecules into simpler substances, such as carbon dioxide. This also implied that life based on carbon could not exist on Mars. However, in over two decades of searching, no "oxidants" have ever been found on Mars. In addition, several of the assumptions that argued against life on Mars have been shaken by new discoveries, including the ubiquitous presence of microbial life in even the most inhospitable Earth environments, telescopic evidence of water on the Martian surface, and the presence of organics in Martian meteorites. Thus, a re-examination of the original Viking experiments and data have regained a spotlight in the media.
As early as 2011, NASA plans to launch a probe to the planet Mars, collect Martian soil samples, seal them in a canister, and then return them to the surface of the Earth. Proponents of the so-called Mars Sample Return Mission assert that acquiring soil samples on Mars and studying them in Earth-based laboratories is the most effective way to remove the ambiguity surrounding the interpretations of Viking data, and would permit direct microscopic observation of the soils for the presence of putative Martian microbes. Opponents of the Mars Sample Return Mission passionately believe such a mission could be extremely dangerous to the Earth's ecosphere, and possibly lead to a global public health epidemic or even extinction of the human species. Opponents of Mars Sample Return point to examples in fictional literature of the disastrous consequences of extra-terrestrial contact — H.G. Wells' War of the Worlds and Michael Crichton's The Andromeda Strain — in an attempt to influence public opinion to kill funding for the mission. Proponents of the Mars Sample Return Mission tend to argue that even if life does exist on Mars, their opponents exaggerate the risks to life on Earth, and maintain that possible "back-contamination" is remote.
In this scenario, fictional Senator Mark O'Neil, Chairman of the United States Senate Standing Committee on Commerce, Science, and Transportation, has convened a public hearing on the Mars Sample Return Mission. Budget deficits and increasing criticism from the international community have forced the committee to reconsider the mission. The setting is the United States Senate Floor in Washington DC sometime in the early 21st century. The Senators have brought three expert witnesses on a panel to testify in this public hearing on whether to continue funding for the Mars Sample Return Mission. The first expert is Dr. Heinrich Grossman, a physicist and the Planetary Protection Officer for NASA, who strongly supports the mission. The second expert witness is Dr. Floyd Dow, a professor of biochemistry from the University of California at Los Angeles and scientific consultant to the International Committee Against Mars Sample Return (ICAMSR). The third expert witness is Dr. Elizabeth Cruz, a geologist with NASA's Ames Research Center. Dr. Cruz takes a more neutral viewpoint, somewhere between that of Dr. Grossman and Dr. Dow. The scene opens with Senator O'Neil initiating the questioning of Dr. Grossman.
Image Credit: Image of Mars taken by the Hubble Telescope on June 26, 2001. Upon its release date (July 5, 2001), this photograph was considered in many circles to be the "best" photograph ever taken of the Red Planet from an Earth-based telescope. NASA and The Hubble Heritage Team (STScI/AURA).
Acknowledgment: J. Bell (Cornell U.), P. James (U. Toledo), M. Wolff (Space Science Institute), A. Lubenow (STScI), J. Neubert (MIT/Cornell). Image and further details can be viewed at http://hubblesite.org/news_.and._views/pr.cgi.2001+24.
Date Posted: 2/20/02 nas
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