Planetary protection for a Mars sample return: Difference between revisions
Planetary protection for a Mars sample return (edit)
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* Biohazard potential of any martian micro-organisms. They noted that extremophiles have not yet been shown to pose significant biological risk to humans. However in chapter 5, they note that there are comparative studies of extremophiles and of human pathogens "suggesting that evolutionary distances between nonpathogenic and pathogenic organisms can be quite small in some instances." As a result they concluded that the potential risks of biological epidemics can't be reduced to zero.<ref name=nrc2009_3p46>{{cite report |title=Assessment of Planetary Protection Requirements for Mars Sample Return Missions |publisher=National Research Council |year=2009 |chapter=5: The Potential for Large-Scale Effects" |page=46 |url=http://www.nap.edu/openbook.php?record_id=12576&page=46 |quote=''As reviewed in Chapter 3, extreme environments on Earth have not yet yielded any examples of life forms that are pathogenic in humans. However, it is worth noting in this context that interesting evolutionary connections between alpha proteobacteria and human pathogens have recently been demonstrated for natural hydrothermal environments on Earth, suggesting that evolutionary distances between nonpathogenic and pathogenic organisms may be quite small in some instances. It follows that, since the potential risks of pathogenesis cannot be reduced to zero, a conservative approach to planetary protection will be essential, with rigorous requirements for sample containment and testing protocols.''}}</ref>
* Would the sample include micro-organisms not already delivered to Earth on martian meteorites? To assess this, they estimated that several meteorites a year probably impact Earth from Mars. So the transfer of sufficiently hardy life forms from Mars to Earth via meteorite seems plausible.<ref name=nrc2009_5p47a>{{cite report |title=Assessment of Planetary Protection Requirements for Mars Sample Return Missions |publisher=National Research Council |year=2009 |chapter=5: "The Potential for Large-Scale Effects" |page=47 |url=http://www.nap.edu/openbook.php?record_id=12576&page=47|quote=''If the 1:100 ratio is accepted as being representative, then of the roughly 500 meteorites that fall on Earth every year, perhaps five are from Mars.''}}</ref> However, they observed that meteorites in current collections spent from 350,000 to 16 million years in space, and though theoretical models show that shorter transition periods are possible, concluded that the much shorter transit time of a sample return protected in a container could preserve lifeforms that would not survive the passage on a meteorite.<ref name=
''...It should be noted that martian materials transported to Earth via a sample return mission will spend a relatively short time (less than a year) in space - all the while protected in containers. (Note that researchers have yet to discover compelling evidence of life in any meteorite, martian or otherwise.) Thus the potential hazards posed for Earth by viable organisms surviving in samples is significantly greater with a Mars sample return than if the same organisms were brought to Earth via impact-mediated ejection from Mars.''
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