The Problems of Contaminating Mars with Earth’s Microorganisms
Rodrigo Abans shares his ethics & society case study, which he completed as part of our Young Scientist Program.
There has been much concern about whether humankind is taking enough care in space exploration. There are a plethora of ethical issues. One of these concerns is the fact that anything that goes offworld carries a certain amount of dormant microorganisms. This led to the decision of destroying the Juno spacecraft by crashing it into Jupiter instead of risking an accidental crash on one of the potentially habitable moons, e.g., Europa, at the end of its lifetime. Though a rather distant situation, a closer one lies at the heat of the debate and is of utmost importance: Mars’ growing exploration.
Mars already has about 13 objects on its surface, seven of which have crash-landed (one of them, the Mars Climate Orbiter, was disintegrated on Mars’ surface during entry). Besides that, a total of nine satellites could eventually fall on Mars. This is very concerning because the objects which weren’t made for landing on Mars don’t belong to the same Committee on Space Research (COSPAR) planetary protection category (landers and rovers fall in VI and orbiters in III categories), meaning that sterilization caution was smaller than for those satellites that crashed and those that might do so. Another important cause of concern is that much more has been discovered about the microorganisms’ resilience to outer space and Mars’ environmental conditions in the last years, which brings the question of whether the Curiosity rover should approach areas that could potentially shelter and nurture dormant extremophiles that might be somewhere in the rover, thus contaminating Mars. Perhaps even more concerning is the apparent race between private and governmental space agencies to send humans to Mars. Although scientifically exciting, it leads to worrisome questions about the ethical and social consequences of such voyages. Maybe, it is just that everything seems to be happening too fast and fundamental questions have not been properly answered, or even addressed yet.
Either way, it’s always important to consider the issue of how humans affect the environment, mainly those offworld. Taking into consideration that it is almost inevitable for humans to travel to Mars in person and that artificial objects are already being sent there, to what extent do all the actions pose the threat of a possible contamination with Earth’s microorganisms? On Earth, microorganisms are virtually everywhere: thriving in the cold and dryness of Antarctica, deep within mines’ untouched rocks and even in abyssal hydrothermal vents. But one should not underestimate everyday microorganisms’ survival capabilities, also because the huge majority of microbial life is uncultivated in laboratory, thereby preventing its survival capabilities’ study. Nevertheless, lots of Bacteria and Fungi spores have been tested in many adverse conditions under controlled environments and have been shown to resist most of those circumstances for hours or even more than a year if properly shielded from solar radiation (as observed in some experiments on the International Space Station—ISS). Some scientists even suggest that some of the toughest microorganisms might survive for millions of years inside an asteroid, allowing for panspermia. Because of this, some researchers argue that an acceptable rate of contamination caused by humans should be equal to or less than the rate at which material naturally ejected from Earth hit other planets.
No matter how good the sterilization procedures for rovers and orbiters are, there will always be a small, but not insignificant, probability that a certain amount of spores are somewhere within the instrument. Spores are the most resistant form of microorganisms, thus giving rise to most concern. Having said that, if life on Mars is ever found, how will it be possible to ascertain whether it is of independent origin or it came from Earth in a remote past or worse, inadvertently during Mars’ exploratory missions? One classic way to approach such questions is to do a phylogenetic study by comparing genetic and morphological differences between Martian and terrestrial microorganisms. If such differences are significant, then and maybe, it will be of an independent origin. However, today’s technologies for analyzing possible features that might answer those questions directly on Mars are very limited. Perhaps when the first manned missions start, teleoperation (tripulated orbiting spacecrafts commanding robotic operations on the surface) and suitport (an alternative to airlock which relieves most of contamination risks) technologies might be advanced enough to shorter communication latency and enable analysis closer to the operators.
It is very likely that humankind will try to build settlements on Mars’ surface for further scientific exploration, even if the existence of life has been confirmed or hasn’t been yet detected, if there is any. Therefore, the spread of microorganisms from Earth is almost inevitable, either on purpose or not. Potentially speaking, some magnitude of biological altering will be achieved, intentionally or not, and this is something to be aware of. Of course, nothing as large scale as terraforming may happen until the next century or so, but do humans really have to introduce microorganisms into Mars, even if accidentally? Will there be means of circumventing or minimizing this possibility? If not, what is the ethical extent of such actions, especially when terraforming a contained area (microterraforming)? One reason pushing us forward to do it is the scientific venture, with probable gains for society with technological development and the sure gain of knowledge from understanding nature. The beginning of cloud computing with SETI’s research and the establishment of global connection with satellites are just a few examples of the benefits and commodities that derived from space venture.
It is fair to address the issue of why it shouldn’t be done. One good reason lies in the unknown risks and damages that would only be revealed in the long term (if not decades, centuries). If Earth’s microorganisms ever reach some place on Mars where they can survive, how far can they spread? And, in the process, how will they evolve and how fast would that be? And, again, to what extent will they be able to adapt to the different Mars’ environments? Let us make it more complex: in case extant microbial life on Mars is found and it is concluded that it shares the same origin as life on Earth, i.e. are evolutionarily related, whether it came from recent contamination (on board of man-made objects) or from ancient lithopanspermia (a life-containing meteorite from Earth), should one regard Mars` biomes as one does with biomes on Earth? Life that came from ancient times has a larger scientific value than life from recent contamination because at the same time it is well-adapted to Martian environment and it might give a insight of the early life on Earth. Last, but not least, what if one concludes that microbial life on Mars has independent origin, with no relation to Earth’s? How does humankind simultaneously preserve such treasure and explore it scientifically and in a non-destructive way? Challenging, isn’t it?
In the end, human actions will depend highly on the appropriate technological tools and knowledge for the specific case on the hands, as well as for the balance between the associated risks and gains. One thing is for sure: the clock is ticking. It is of utmost importance that researchers, entrepreneurs and public policy-makers must work together in finding the best ethical way to explore Mars with minimum intervention, and consciously evaluate the consequences in the close and distant future.