In the coming decades, as we gear up for a more in-depth search for life on Mars, as well as visits to potentially habitable ocean moons in the outer solar system, should scientists start addressing the ethical concerns of accidentally contaminating these worlds with Earthly microbes, as well as the scientific implications?
By Keith Cooper | SPACE.com
That’s the question posed by a trio of scientists who are arguing for a shake-up in how we think about planetary protection.
If there is life on Mars, or in the waters of the Jupiter moon Europa or the Saturn satellite Enceladus, then we risk contaminating it with terrestrial microbes before we can even get the chance to discover that life. Despite our best efforts, no mission goes into space completely sterile, but there are requirements: the Outer Space Treaty, which was signed by all space-faring nations in 1967, stipulates that every effort must be made to protect other worlds from contamination. The Committee on Space Research(COSPAR) has guidelines that state that any mission designed to look for life on other worlds must not have a probability greater than 1-in-10,000 that a single microbe carried on board will contaminate potential extraterrestrial habitats. [6 Most Likely Places for Alien Life in the Solar System]
The requirement is dictated by the need to ensure the scientific integrity of the discovery of life. How could we be sure we have found life native to another world if we have already contaminated that world with Earthly microbes? There is, however, another aspect to planetary protection that tends to be overlooked, which is that the potential alteration of alien biospheres in the face of invasive terrestrial microbes is also an ethical issue.
Currently, the only potentially life-bearing world that could have been contaminated by microbes hitchhiking on a spacecraft is Mars. In 2012, researchers catalogued 298 strains of extreme bacteria that were able to survive the sterilization process in European Space Agency clean rooms, and it is expected that there are dormant terrestrial microbes on Mars today, although it is not suspected that any active contamination has yet taken place.